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EPOXY OILSEEDS

Vernonia galamensis is a new potential industrial oilseed crop that originated in Ethiopia. It has unique properties, which makes it economically and ecologically interesting. The status of germplasm collection and collection sites across the different ecological zones with detailed description and current research in Ethiopia are described. Data bases have been also developed for the accession and collection sites.

Studies on variability of characters in V. galamensis collections at three contrasting agroclimatic zones during the last four years showed a highly significant difference for days to emergence, plant height, stem diameter, number of primary and secondary branches, number of primary and secondary heads, leaf number per plant, days to heading, flowering, physiological maturity, seed yield per plant, seed yield per hectare, seed number per head, 1000 seed weight, and oil content. The existence of variability indicates the potential for an effective basis for selection and improvement within characters. The mean performance of the accessions for the same characters showed significant difference using Duncan's multiple range test. The agronomic practices developed through this research effort are given as recommendations for growing this crop under Ethiopian conditions.

Harvesting and processing of the seed are described and presented. The potential of the crop is discussed within the framework of the agricultural system in Ethiopia.

Stokes aster (Stokesia laevis) is a potential natural seed source of vernolic acid (12,13-epoxy-cis-9-octadecenoic acid) with several problems limiting its culture as a crop. Among these is the fact that Stokes aster does not produce seed in its first year of development. Our objective was to compare productivity of Stokes aster relay intercropped with soybean with spring and fall plantings of monocropped Stokes aster. This comparison was initiated in 1992 and was repeated over a three-year period.

Stokes aster growth under the soybean canopy was significantly less than that of spring monocropped plants. However, after the soybean canopy was removed at harvest, the relay intercropped Stokes aster recovered before reproductive bolting. This resulted in seed yields equivalent to spring monocropped Stokes aster. Seed yields from these small plots varied considerably, but averaged about 1,000 kg/ha. Planting in the fall of the same year instead of the spring did not allow plants to achieve adequate size for a vernalization response and most plants did not produce flowers the following spring.

Regardless of cropping system, production longevity of this perennial was no more than three years after initial reproductive development. Weed encroachment, disease, and mound building by fire ants (Solenopsis invicta) caused loss of stand over time at our location.

Vernonia galamensis is a new oilseed crop. At present, no publications or recommendations are available regarding the nutrient and fertilization requirements for vernonia. To elucidate some of these requirements, experiments were conducted in the greenhouse with two varieties of V. galamensis, var. ethiopica and petitiana.

In the first experiment, the plants were grown in soil-less medium, irrigated, and fertilized daily with 7:3:7 Shefer liquid fertilizer at three levels: 0.5, 1.0, and 2.0 l/m³. Plants in the control were fertilized every two weeks at a rate 36 times lower than the low treatment of 0.5 l/m³. The following parameters were determined: time of flowering, shoot elongation, number of branches and capituli, seed yield, and oil and vernolic acid contents. It was found that, in all aspects of growth, the control plants of both varieties had suffered greatly. There were no differences in performance among the three fertilization treatments for the var. petitiana; however, the performance of var. ethiopica was optimal at 1.0 l/m³ of fertilizer. The growth parameter most affected was production of primary branches that lead to production of more flower heads. Fertilization also had a positive effect on the level of oil and vernolic acid.

In the second experiment, plants of var. ethiopica were grown at five fertilization regimes varying in nitrogen and phosphorus: 7:3:7, 14:3:7, 3.5:3:7, 7:6:7, and 7:1.5:7 (1.0 l/m³). It was observed that high nitrogen caused a slight but significant decrease in biomass and seed yields and stimulated plant senescence and drying. Plants grown under high phosphorus had slightly more biomass and seeds. Fertilization did not affect the time of flowering.

Establishment of a new industrial crop such as vernonia (Vernonia galamensis) could be an alternative to farmers who need a "high cash" crop as a primary source of income. This is crucial in states such as Virginia where farms consist of relatively small acreages and depend upon tobacco as their "cash" crop in prior years. Vernonia is an annual herb and native of East Africa. It grows in areas with as little as 200 mm of seasonal rainfall. Plantings in Eritrea, Kenya, and Zimbabwe confirmed that V. galamensis has an excellent seed retention compared with V. althemantica.

The progress in developing improved vernonia germplasm has increased the national and international interest in this plant as a good source of seed oil rich in vernolic acid. The existing V. galamensis germplasm collection at USDA/ARS is limited to 33 accessions. Additional accessions were collected from Eritrea through the support of USAID grant. The seeds of the newly collected accessions were multiplied and planted at two locations in Eritrea. In addition to the agronomic studies, seeds were analyzed for oil, vernolic acid, and lipase activity.

Significant variations in oil and vernolic acid contents among accessions were found. Oil ranged from 13.8 to 53.7% with a mean of 24%. Vernolic acid ranged from 40 to 75% with a mean of 62.4%. A positive and significant correlation (r = 0.28**) between oil content and vernolic acid was found. This indicates that breeding vernonia for higher oil content will increase vernolic acid content. Highly significant and negative correlations (r = -0.90, -0.82, -0.95, and -0.96) were found between vernolic acid and palmitic, stearic, oleic, and linoleic acid, respectively. Agronomic traits of the accessions and the breeding strategies will be discussed.

Euphorbia lagascae seed contains high levels of vernolic acid, a C-18 epoxidized fatty acid with potential use by the paint and coating industries. Our interest in euphorbia is because of its drought tolerance and grows well in the warm, Mediterranean climate of southwest Oregon. Use of "non-shattering" mutants from Spain has allowed evaluation of agronomic requirements. Time of planting and weed control are two factors that are important in plant growth, yield potential, and the mechanics of harvesting.

Early spring planting dates have produced plants that are more mature and more amenable to swathing and subsequent windrow combining by early September than later spring planting dates. However, early spring planting has often been hampered by wet weather. Euphorbia seeds that shattered on the ground during harvest have shown the ability to germinate in the fall and survive through the winter, suggesting that fall planting may be possible. A planting date study began in 1997, with four fall planting dates and two spring dates. Planting in late August and early September resulted in large, vigorous plants by April, whereas plants seeded in late September and early October survived the winter, but the plants were much smaller and less vigorous by April. Early March and early April planting dates were also included in this study. If trends continue, an early fall planting would likely allow harvest in midsummer, reducing irrigation requirements as well as avoiding weather-related harvest problems in September and October. Also, plants that are well-established by early April can much more easily compete with the summer weeds that emerge then, possibly avoiding extensive cultivation and herbicide use. Detailed seed and oil yield results will be discussed further.

Concurrent experiments will evaluate the tolerance of euphorbia to various post-emergence herbicides. By building on prior experience with pre-emergence herbicides, these results will allow growers the means to minimize weed competition during the germination and seedling stages, prior to canopy closure when euphorbia becomes very competitive. Greenhouse testing to date suggests that euphorbia is tolerant to a number of compounds, but plant growth stage and herbicide rate are important in some cases. Detailed results from ongoing tolerance evaluations in the greenhouse and field will be discussed as well as yield comparisons in the field tests.

Our study was undertaken to describe changes in fatty acid composition and oil content that occur during seed development in Vernonia galamensis. A second objective was to determine the progression of lipase activity in seeds as they mature.

Vernonia was planted in April 1997 at the U.S. Water Conservation Laboratory in Phoenix, Arizona. Heads were harvested at 4-day intervals from 7 to 56 days after anther emergence. Three replications of seven vernonia accessions were collected on each harvest day. Seeds were stored at -80 ^oC until analyzed for oil content and oil composition (fatty acid distribution). Lipase activity was determined by measuring free fatty acids present in the seeds at the time of oil extraction. Oil constituents were first separated by solid phase extraction columns using a procedure developed for this study. The amount of oil was determined using gas chromatography. Free fatty acid distribution was determined using a colorimetric method.

The information from this study will help determine optimum harvest time for vernonia seeds. It will also be useful in our study of the heredity of these traits.

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FOOD
 

Garbanzo bean also known as chickpea (Cicer arietinum) is an important source of protein in human diets. It is grown in the U.S. almost exclusively in California and the Palouse region of eastern Washington, northern Idaho, and eastern Oregon. Garbanzo bean production was introduced to southwestern Colorado in the early 1980's, but was short-lived due to agronomic, processing, and marketing constraints. Renewed interest in garbanzo bean in recent years has been prompted by the release of more adapted varieties and the need for alternative crops in southwestern Colorado.

Agronomic research at the Southwestern Colorado Research Center in 1994-1997 shows a yield potential of 1,120 kg/ha (1,000 lb/a) under dryland conditions and more than 2,240 kg/ha (2,000 lb/a) under irrigation of several garbanzo bean varieties. In comparison, the county yield average of pinto bean variety (Phaseolus vulgaris L.) rarely exceeds 448 kg/ha (400 lb/a) under dryland conditions and 2,016 kg/ha (1,800 lb/a) under irrigation.

Garbanzo and dry beans can be grown using similar equipment and cultural practices. An advantage of garbanzo beans over commonly grown dry bean varieties is the possibility of direct combining. Furthermore, garbanzo bean appears to be more frost tolerant than pinto bean, thus allowing earlier planting. A study by Adobe Milling Inc. shows the potential for much higher economic returns by growing garbanzo beans instead of pinto bean.

The quality of garbanzo bean seeds produced in southwestern Colorado seems adequate for dry packing and/or canning. However, the uniformity of seed maturity has been a problem in wet years resulting in a high number of stained seeds. Research is underway to determine the influence of planting date on seed yield and quality of several garbanzo bean varieties.

Increasing world population and increasing emphasis on protection of the environment require development and production of legumes. These crops provide protein-rich food and feed, and reduce inorganic nitrogen fertilizer applications due to their ability to fix atmospheric nitrogen. The New Crops Program of Virginia State University, established in 1991, has evaluated a wide array of legume plants for production in Virginia and adjoining states. The potential legume crops identified were chickpea, faba bean, mungbean, and pigeonpea. Since 1997, the white lupin is also being evaluated as a winter grain legume.

Because the Virginian farms are close to the Washington, D.C. metropolitan area, where international community is familiar with these crops, these growers can capitalize on the demand for the mature and immature seeds of chickpea (Cicer arietinum L.), faba bean (Vicia faba L.), and pigeonpea (Cajanus cajan (L.), Millsp.).

Production of mungbean (Vigna radiata (L.) Wilczek) as a summer crop, following winter wheat, can reduce imports of 5-7 million kg of mungbean into the United States for sprout manufacturing and other food uses. Research conducted during 1993 and 1994 showed that the mungbean yield of approximately 2,700 kg/ha is possible when it is planted in May.

White lupin (Lupinus albus L.) is making a comeback in the southern United States due to its high potential in both conventional and sustainable production systems. It can fix 150 to 200 kg/ha nitrogen for use by a succeeding crop. The fiber-rich lupin flour is gaining attention as a food source for humans. The nutritionally-rich lupin flour with its high content of potassium, calcium, carotene, and protein can be used to enrich pastas, cake mixes, cereals, and other baked goods. Sweet lupin seeds lack trypsin inhibitors and can make a valuable contribution to dairy, beef, swine, sheep, and poultry rations because high temperature cooking to eliminate anti-nutritional factors is not needed.

Both desi and kabuli types of chickpea have shown promise under Virginia conditions. The mature seed yields of desi types (small-seeded) have ranged from 876 to 1,400 kg/ha and those of kabuli (large-seeded) types from 307 to 1,082 kg/ha when planted in March and harvested in July.

Selected pigeonpea genotypes have yielded more than 10,000 kg/ha of green immature beans and approximately 1,900 kg/ha of dry beans.

Currently, 390 genotypes of faba bean and 284 genotypes of lupin are being evaluated to identify desirable genotypes for development of cultivars adapted to the agro-climatic region of Virginia and adjoining states. Detailed results of research efforts with these crops will be presented.
 
 

Amaranthus hybridus is a nutritious, fast growing vegetable crop, with the potential for increased use in the semi-arid regions of the world. A sustainable pest and disease management approach for the cultivation of A. hybridus in South Africa requires a thorough understanding of the abiotic and biotic factors that affect the crop. Fungal and insect relationships are especially relevant because they play important roles in the ecology of most cultivated plants.

Our main goal was to identify fungi and insects associated with A. hybridus cultivated in monoculture systems. Special attention was devoted to endophytic fungi associated with A. hybridus. True endophytic fungi live entirely within living plant tissues, but do not elicit disease symptoms. They can act as bioregulators of plant health or provide protection from pathogenic fungi and phytophagous insects. Certain endophytic fungi (latent-infecting fungi) can cause disease symptoms when induced by adverse environmental conditions or host maturity.

The first objective of this study was to identify and quantify frequencies of endophytic fungi associated with A. hybridus and to determine the influence of soil amendments and irrigation on their occurrence. Five-month-old A. hybridus plants were sampled from four treatments comprising the addition of fertilizer or manure to irrigated soil; wood ash to non-irrigated soil; or control plots that were not amended nor irrigated. Ten leaves, 10 petioles, and 10 roots from each of five plants per treatment were surface sterilized to remove exterior micro-organisms. Small sections of tissue were placed on corn-meal agar and observed after five days incubation. Significant differences in recovery of fungi occurred among the four treatments (P<0.001 for all tissue types). The highest recovery was from the fertilized/irrigated treatment for all tissues (mean 97% for all tissue types). Differences in species composition also occurred among plant tissues (P<0.001) and among soil treatments (P < 0.001). The most common species isolated from leaves and petioles was Alternaria alternata (90% and 70% respectively, for all samples). Different fungal genera predominated in the roots. These observations suggest that both the abundance and species diversity of endophytic fungi in A. hybridus are influenced by site conditions.

The second objective was to identify fungi associated with tissue decay observed in larval galleries of the pigweed weevil (Hypolixus haerens), the main pest of A. hybridus in South Africa. Six-month-old A. hybridus stems were split and small samples of discolored tissue and associated larvae were aseptically placed on corn-meal agar in petri-plates and incubated for four to seven days. The most common species isolated from both discolored tissue and larvae was Fusarium subglutinans (50% and 36% of the samples respectively). Additional species isolated from stems included other Fusarium sp. (19%), Phomopsis sp. (11%), and A. alternata (10%). Additional species isolated from the larvae included other Fusarium spp. (40%), Phomopsis sp. (4%), and A. alternata (6%). Inoculation studies revealed that isolates of F. sambucinum, F. oxysporum and F. subglutinans can act as pathogens independent of the pigweed weevil. The potential for significant disease loss associated with this insect-fungal association warrants further investigation.
 
 

The aim of this investigation was to measure the effect of a summer sowing date on the potential productivity of tomatillos (Physalis ixocarpa) and cape goosberry (Physalis peruviana L.) (syn. P. edulis).

Plants were grown with seeds obtained from Mexico (P. ixocarpa) and from Colombia (P. peruviana). They vary considerably in their developmental, morphological and biochemical characteristics. The trial was conducted under field conditions at the Agronomy Facility, Buenos Aires University (34° 36' S and 58° 29' W). Seeds were planted in a greenhouse on 20 December 1996 and the seedlings transplanted to the field on 14 January 1997. A randomized complete design with four replications was used. Each replicate consisted of four 2 m rows, 50 cm apart with a plant separation of 50 cm. At the end of the growing season on 25 April 1997, observations were taken on the total number of nodes m^-2; number of nodes m^-2 on the superior and inferior auxiliary branches, and total number of fertile nodes m^-2 (a single fruit per fertile node), and on stem, leaf, root and fruit dry weight m^-2. The results were subjected to analysis of variance. Differences were considered at the (P = 0.05) significance level.

The dates of first flower opening by 50% and of first fruit harvest were on 4 February 1997 and on 24 March 1997 for P. ixocarpa; and, 20 February 1997 and 7 April 1997 for P. peruviana. The total number of nodes m^-2 did not differ significantly between genotypes during the trial, but node patterns varied significantly between genotypes. The number of nodes m^-2 on the superior auxiliary branches was highest on P. ixocarpa (258 vs.161) as was the number of fertile nodes m^-2 (292 vs. 76). There were no differences on total biomass production m^-2 between genotypes, although there were differences on biomass partitioning. Leaf dry weight m^-2 was lowest (248 vs. 760) and fruit dry weight m^-2 was highest (1,221 vs. 37) on P. ixocarpa.

The average fresh weight per fruit was 22 g for P. ixocarpa and 4 g for P. peruviana. The lower leaf dry weight m^-2 measured at final harvest on P. ixocarpa compared with P. peruviana, was the result of the differences in the demand of the reproductive sinks, and was responding to a shorter phenological pattern.

P. ixocarpa had the greater economic yield and lower leaf dry weight at final harvest than P. peruviana. This is related to the growing conditions. P. ixocarpa is a short season genotype, and with earlier planting dates we could expect more than one cycle of production. P. peruviana must be planted earlier if we expect to improved its economic yield.
 
 

Apios americana, also known as the groundnut or potato bean, has long been used as a food source by Native Americans perhaps as a cultivated plant. This member of the Fabaceae has a number of small tuberous rhizomes that are edible and may reach two inches in diameter in the wild. The potential as a modern crop has long been recognized.

In 1995 and 1996, an electrophoretic analysis was done to understand the evolution and origin of the triploid races of A. americana by comparing banding patterns of this cytotype with geographically associated diploids. The triploids are found in the northern part of the range and may be important in developing this species as a crop in the Northeast. Using this analysis, it became evident that diploid races had a great deal of variation within and among populations. In addition, two different genotypes were identified in the triploids. To test the possibility that either A. priceana or A. fortunei contributed a genome to the triploid, their isozymes were also investigated. It was shown that these species had unique alleles not found in either the diploid or triploid populations of A. americana. This reveals that these congeners may have unique characteristics that could be used to improve the common groundnut. The small sample of the threatened North American species A. priceana showed great uniformity in banding patterns. This may mean that it is self pollinating, which could allow useful varieties to be produced true to type from seed, which is important, because unlike A. americana, it is not easily asexually propagated.

Apios priceana may be useful in agriculture because of its single large tuber that may be easier to harvest than A. americana. In addition to using isozymes or DNA techniques to insure capture of a high level of diversity while domesticating A. americana, research involving trials and selection need to be done in several regions of the United States. Varieties from Louisiana State University were grown at the University of Vermont horticultural farm in the summer 1996. It quickly became evident that most of the LSU selections were not appropriate for cultivation in New England. A few improved varieties did succeed, but were the types that produced a large number of smaller tubers. More work and selection has to be done in each area to ensure that varieties will yield in different regions. In addition more research on A. priceana could be done. Nutritional analyses showed its tubers to be inferior to the common groundnut for human consumption. The members of the genus Apios have potential to be developed as agricultural crops. A deliberate and directed effort must be made to capture the genetic diversity of the wild populations while improving their production. A broader genetic base may allow plants to be grown in different climatic regions and reduce the chances of a pathogenic disaster.
 
 

The study was conducted to determine the effect of four irrigation methods combined with two soil moisture levels on water use efficiency (WUE), fruit quality, and plant growth of pepper in the Las Cruces region of southwestern New Mexico state. Drip, furrow, alternate furrows, and alternating-alternate furrow irrigation methods were evaluated. The soil moisture levels studied varied with the irrigation method (-0.025 and -0.035 MPa of soil matric potential in drip irrigation, and -0.045 and -0.055 MPa in the furrow treatments). Water was applied based on Penman’s potential evapotranspiration (PET) equation and irrigation efficiencies of 90% for drip irrigation and 85% for furrow irrigation. Alternate treatments received the equivalent of 85% of the water applied to furrow irrigation.

Drip irrigation produced the highest yield (green and red) and the highest WUE for green pepper, whereas no significant differences occurred between the every furrow irrigation compared with the alternate treatments. Pod quality (weight, length, and width) was better under both drip and furrow irrigation in three of four parameters evaluated. Drip irrigation promoted the highest leaf area; however, there were no significant differences among the four irrigation methods for the leaf area index (LAI). Similarly, the LAI values obtained from the four irrigation methods were considered as good values because they oscillated between the optimum range (3-5).

Total aerial dry matter, plant height, and plant stem diameter reached the highest values under drip irrigation. The two soil moisture levels evaluated did not produce a significant effect on any of the parameters measured. Therefore, the irrigation timing for pepper under drip irrigation can be when the soil matric potential is at either -0.025 or -0.035 MPa; however, for furrow irrigation, it is recommended at -0.055 MPa. Additional research is needed in getting the optimum soil moisture level for applying irrigation in pepper.

The alternate furrow treatment produced similar effects on important parameters such as yield (green and red) and WUE, and required 15% less water compared with the traditional every furrow irrigation. Thus, alternate furrow irrigation may be as good as other irrigation methods to produce chile pepper in areas with scarce and/or expensive water.
 
 

Corn stover is by far the largest single available biomass not being used, representing more than 70% of the total waste, including municipal solids. An estimated 220 million dry tons remain each year as aboveground residue.

Conversion of corn stover to sugars has been stymied for years due to cost. Environmental benefits, wider adaptation of sustainable farming practices and the relentless improvements in biotechnology are expected to overcome the economic hurdle within the next five years and recast the corn sweetener industry.

A limited amount, less than 1%, is collected for industrial processing. Although some bales are made for bedding, their amount is a small, less than 10% of the total. And, after use, they are recycled back to the field. The 90%+ must be plowed under for planting to proceed on schedule, insuring the best yield, eliminating insects and disease harbored by the stover, and reducing the threat of alpha toxins in the corn.

Because of plowing, a carbon deficit occurs in the soil, losing more carbon than in the residue plowed under due to the exposure of all the carbon sequestered in the soil to the atmosphere - contributing further to the greenhouse gas, CO₂.

Also, additional fertilizer is required for the stover. Its C/N ratio of 30:1 must be decreased to about 10:1, if no N is added. The cash crop harvest is significantly affected while the residue slowly decomposes. Again, much of the nitrogen is lost, when plowed, from the oxidation of the residue by the organisms when exposed to the atmosphere.

Innovative corn stover harvest, collection, and transportation practices have reduced the corn stover cost to $30 - $35 per dry ton delivered in western Iowa where 50,000 acres were collected in the 1997 crop year. Planned improvements in productivity and storage stability are expected to reduce costs to less than $30/ton.

The sustainable amount that can be removed depends on soil, topography, crops, crop rotation, tillage practice, and environmental constraints. Just 1/3 of the total corn stover converted to glucose with improved cellulase enzyme systems currently being developed result in 64 billion lbs., more than twice the sweeteners shipped by the corn refiners in 1997, based on 38% cellulose in the stover.

Corn stover also contains 32% hemicellulose. When converted to C5 sugar that has less human food value, the most likely future use is a nutrient for fermentation processes, with the largest being alcohol. By converting 80% of the hemicellulose into alcohol, and employing any of at least three engineered organisms presently being developed, 3.6 billion gallons of ethanol can be produced, again 2X the 1.3 billion gallons produced annually. The targeted cost is less than $1/gal.
 
 

Stevia rebaudiana Bertoni is a new crop that is getting world attention for its medicinal use as a non-caloric natural sweetener. Commercial production is limited due to extremely poor field stand establishment. At present, commercial propagation is accomplished by stem cuttings. The objective of this research study was to determine the causes and factors for low germination of stevia.

Initially, stem cuttings from established potted S. rebaudiana "Chinese" genotype plants were rooted and transplanted into 24-cm plastic pots. At blooming time, the plants were conditioned to bumble bee (caged), hand, and wind pollination treatments. "SR8" genotype was used as a source of cross-pollination. Also, plants were hand-selfed and a control group was established. The experiment was carried out under greenhouse conditions. Seeds were harvested by hand and separated by color: black and tan. The germination test was conducted under a fluorescent light and dark treatments at 24°C. The number of blossoms produced per plant was recorded. Data were collected and analyzed with five replications for germination and seed weight.

Black seeds clearly and consistently exhibited better germination than the control treatment across all treatment methods. Results showed an average of 85% germination for a composite of three cross-pollinated methods under fluorescent light treatment, whereas the tan seeds under similar conditions had 7% germination. Seeds germinated under darkness resulted in 56% germination for all cross-pollinated methods for the first seven days of germination. However, an additional five days were needed to improve germination to 73%.

When pollination treatments were compared, the control group showed the lowest germination and the seeds were all tan colored. The data suggest that pollination treatment is needed. Furthermore, it is unclear whether cross-pollination is better than self-pollination. Black seeds weighed 300 mg/1,000 compared with 190 mg/1,000 for the tan seeds. The relationship between the number of blossoms per plant and the percent germinable black seeds demonstrates that the fewer the number of blossoms per plant, the higher the number of black seeds produced, and a higher germination rate. However, the data showed that the highest actual yield of germinable black seeds is produced by plants having a medium number of blossoms.
 
 

The yakon (Smallanthus sonchifolius, Heliantheae, Asteraceae) is an ancient Andean root tuber grown from southern Colombia to northwestern Argentina. Unlike other crops, yakon remained restricted to the Andes after the Spanish conquest. Subsequently and particularly in the last century, its overall importance as a crop has been reduced in this region and disappeared from several areas. However, the trend appears to be reversing in recent years. Yakon clones were introduced into New Zealand in the seventies, gaining a small market niche. It was introduced from New Zealand to Japan in 1985 and later to Korea with similar results. In 1993, a clone from Japan was introduced to Brazil and gained acceptance by the Japanese community of Sao Paulo. The first large-scale farm was established in Brazil obtaining yields exceeding 100 t FW/ha. As a result of the success abroad, renewed interest in yakon has developed as a crop in the Andean region.

The main storage sugars in yakon are oligofructans. Due to its low calories and high fiber, yakon is an excellent diet and diabetic food. Traditionally, the root tubers have been eaten raw as a "fruit", sharing places with cherimoyas, avocados, and apples in the Andean peasant markets. In the last years, several processed products have been developed: pickled tubers, sun-dried chips, syrup, and marmalade. More recently, anti-diabetic properties have been demonstrated in the leaves used in herbal teas.

This paper will focus on the historical development of the crop and its potential and limitations in modern agriculture, from low-input organic farming to large-scale conventional agriculture.
 
 

One of the constraints for the commercial production of grain amaranth (Amaranthus spp.) in the United States is the lack of planting equipment able to accurately meter the unusually small seed. Currently, the lowest rate of seed that can be applied is about two million seeds ha^-1. To aid in developing adequate planting equipment for grain amaranth, identification of the plant population that maximizes yield is important. Field experiments were conducted in 1991 and 1992 in western Nebraska to evaluate the effect of plant population on grain yield and agronomic components of grain amaranth. The amaranth cultivar ‘Plainsman’ (A. hypochondriacus x A. hybridus) was grown at plant populations of 2,000,000 (control), 1,400,000, 700,000, 350,000, 170,000, 85,000, and 43,000 plants ha^-1.

Plant population showed no significant effect on grain yield. The study suggests that grain amaranth may compensate for variations in plant population by allocating more energy to reproductive structures in the plant, reducing the effects of solar radiation competition, and developing reproductive secondary branches. Because of its adaptability, amaranth could be planted over a wide range of plant populations with the advantage of lower populations limited to savings in seed cost.
 
 

A great deal of variation in ‘Plainsman’ (A. hypochondriacus x A. hybridus) cultivar, one of the most widely grown grain amaranths in the United States, has been observed in the field. The complexity of its reproductive system along with the breeding strategy employed in its development provided grounds to suspect that residual genetic variance is still present in Plainsman. The well-known phenotypic plasticity observed in the amaranth species might be causing such variation.

To gain understanding on the variability within Plainsman, 140 selfed families from a random sample of this cultivar were evaluated at three different environments in western Nebraska during 1995. Overall, a small amount of genetic variances was observed. Plant height showed the relative largest variance followed by grain yield. No genetic variance was observed in 1,000-seed weight. Broad-sense heritability estimates indicated a similar pattern. Given the size of the estimates, a homozygous genetic structure appears to characterize Plainsman. In contrast, a large amount of plastic variances was observed for the traits studied. Plasticity estimates were by far larger than broad-sense heritability estimates. The study suggests that variation in Plainsman occur mostly by phenotypic plasticity rather than genetic variability.
 
 

Marula (Anacardiacea) is a large dioecious deciduous tree endemic to Southern Africa. The yellow, plum-sized fruits are consumed fresh or processed into liqueur and nectar. The kernel is a source of high quality edible oil. Marula trees exhibit a high degree of morphological and physiological variability. Seed propagated plants and selected grafted clones have been planted at different sites of the Israel Negev for development of marula as a fruit crop for arid areas.

In the present study, we examined whether marula can be distinguished by randomly amplified polymorphic DNA (RAPD) analysis. Twenty 10-bp random primers were chosen to amplify 24 DNA samples isolated from different trees. Fifteen primers gave 2-11 bands from all templates, and of these, four primers gave bands that were unique to a subset of the trees. A single primer gave at least one unique band in 13 of the 24 genotypes. A unique pattern of RAPD bands for each individual tree was obtained using four primers. Vegetatively propagated grafts maintained the RAPD pattern of the mother plant.

Our results show that a high degree of genetic variability is present in marula underlying their morphological and physiological diversity. The ease of RAPD analysis suggests that this technique will become the method of choice for studies of marula varieties and for registration of proprietary cultivars.
 
 

The asteraceous root crop yacon (Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson) is a vegetatively propagated domesticates of Andean South America. As one of the "lost crops of the Incas," it is mostly grown in its native range for subsistence. The sweet and crisp yacon roots are eaten raw and function as "fruits" in traditional food systems. Although it is declining in importance and only sporadically cultivated in the Andes, yacon is becoming increasingly popular in Brazil, Japan, Korea, and New Zealand. Although the fresh roots have high water content (86-90%), dry matter root yields are high (10-12 t/ha in 7-10 months growth period).

We determined the approximate composition of 10 clones representing the geographic range of the species. Compositional diversity was found low with 86-91% of the root dry matter accounted for by carbohydrates, of which 50-70% was oligofructans with an average degree of polymerization of 4-5. The more important non-fructan carbohydrates present in the fresh root are fructose, sucrose and glucose. The starch-free yacon root contains only traces of lipids and 2-4% of raw protein in the dry matter. With 0.2-0.3% of potassium in the fresh roots, yacon is an excellent dietary source of this mineral.

In recent years, entrepreneurial farmers have seized upon market opportunities and developed several attractive products through processing yacon roots. They include air-dried chips, which are similar in texture and taste to apple chips and with a pleasant resinous aftertaste. The roots can also be processed successfully into pickles, candies, and syrups. Interestingly, yacon leaves are also marketed as medicinal tea with putative benefits to diabetics. The existence of such products provides pointers for future yacon product development. High content of sweetening, yet undigestible, fructans in the yacon root fully justify its reputation as a diet food.
 
 

The biological productivity of semiarid lands is typically restricted by the amount of rain. Agricultural systems throughout the world rely on C4 and C3 plants. In Central Mexico, corn and dry beans have been the cornerstones for centuries. However, CAM plants can provide an opportunity to improve the productivity in these regions, due to their higher water use efficiency. Cactus pear, a perennial crop for fruit and fodder production, can enhance sustainability in the long term; however, its adoption as a sole crop during its establishment years represents a significant financial drain for the typical farmer of these regions.

The feasibility of intercropping common annual crops and cactus pear was studied in a series of field experiments conducted in Central Mexico from 1988 to 1995. The northern part of Guanajuato Research Station is located at the southern tip of the Chihuahua-Sonoran desert, characterized for its limiting rainfall pattern, 548?112 mm a year, shallow soils, the traditional cultivation of corn and beans, and the intensive overgrazed natural pasture.

By using the empty spaces between rows of a newly planted cactus pear orchard, up to 677 kg ha^-1 of barley plus 377 kg ha^-1 of canola seed, or 817 kg ha^-1 of dry beans, or 7.45 t ha^-1 of foxtail millet hay were obtained. Based on the barley/canola association as an example, and combining the income obtained from both grains, an estimated 40% of the initial investment in the orchard establishment can be readily recovered without significantly harming cactus pear growth. Yields were obtained in 1990 when the rainfall received in the experimental site totaled 497.8 mm, of which 89.5% was recorded during the growing season. Water usage was optimized by the introduction of simple water harvesting techniques such as tied-ridges and microcatchments.

The area is also prone to water shortages for irrigation purposes, so that the irrigation schedule was designed to cover the most critical stages of the dry bean crop, a staple food among Mexicans. When limited irrigation was provided to the system (10 cm at planting and additional 10 cm at flower initiation), up to 1.28 t ha^-1 of dry beans were obtained, and approximately 25% reduction of the same annual crop without the competition of the perennial crop. Yields of the intercrop decreased in the second year due to the lower number of rows that could be planted and also from the greater competition of the cactus plant. The cactus pear started bearing fruit in the third year, gradually becoming the main asset. Some additional advantages of the system are: better use of fertilizers and more efficient weed control between the rows of the perennial crop.

Other systems to produce fruit and pasture and mature cactus pear pads for fodder and/or tender pads for human consumption are discussed. The water harvesting practices, the associated costs and benefits in the short and long terms, and the overall crop management are described.
 
 

Edamame soybean (Glycine max L.) has been used as a snackfood and vegetable in Asian cultures. It has potential in health food markets because of its high fiber and protein and low fat content. Soybeans have also been associated with lowering risk of certain types of cancers. Colorado State University began experimenting with edamame in 1991.

Production practices were similar to conventional soybeans until harvest. Initial trials were based on planting rates of 78 kg/ha with both furrow and sprinkler irrigation depending upon location. Harvest was accomplished using hand-harvest of green mature bean pods. Salable bean pods at a minimum of 9% Brix and consisting of two or more beans per pod without surface flaws (spots, scratched or tears) were weighed and used as yield per ha. Seed harvest was accomplished using a Mitsubishi BH208 bean harvester. Cut plants were windrowed on canvas tarps until 14% moisture was obtained and were then combined using a modified Hege B125 with an internal belt threshing system to minimize damage. Direct combining studies at Rocky Ford indicated that it was not feasible under normal environmental conditions (RH 18%, daytime temp. of 28-32°C).

Replicated trials in Ft. Collins, Rocky Ford, and Fruita, Colorado show edamame to be a viable alternative crop to conventional crops grown in these communities. Yields of salable pods have ranged from 3,525 to 7,350 kg/ha. Surface or furrow irrigation was found to be critical in reducing bacterial spotting on fruit. Sprinkler irrigation reduced salable pod yields by as much as 40%. Yield loss from single bean pods ranged from 18% in Rocky Ford and Fruita to 27% in Ft. Collins due to climatic variation.

Dry seed yields ranged from 1,870 to 2,540 kg/ha at 12% moisture. Seed quality was affected by timing of harvest. Threshing protocol was limited to the belt threshing system because conventional raspbar threshing caused extensive germination loss. Germination of belt threshed seed ranged from 45 to 80%. Raspbar combined seed ranged from 10 to 28% germination.
 
 

Development of a new commercial crop requires, among other things, research on cultural methods, breeding programs, and evaluation of suitability of cultivars. Kentucky State University (KSU) has had a pawpaw research program in place since 1990. The goal of the program is to develop pawpaw as a new commercial crop. Objectives include: 1) horticultural research for developing new or improved methods of propagation; 2) collection, evaluation, preservation, and dissemination of germplasm; and 3) dissemination of information on pawpaw to scientists, commercial growers and marketers, and to the general public.

To aid in the dissemination of information, a web site is being developed that includes information on current and past pawpaw research at KSU and information on the PawPaw Foundation. On this site, a selected bibliography of publications will include pawpaw and related species, recipes and nutritional information, a guide to buying and growing pawpaws, results from regional variety trials, the database for the National Clonal Germplasm Repository for Asimina spp. located at KSU, and links to other web sites with pawpaw information. The exponential growth of public access to the Internet at home, in business, and in public libraries should greatly facilitate the introduction of pawpaw as a new, potentially high-valued tree fruit crop in Kentucky and the United States.
 
 

Different pruning treatments were conducted on a two-year-old rosehip orchard (Rosa rubiginosa) during 1997. Shrubs were pruned on 24 June and 5 August in the southern hemisphere (36° 03’ S, 72° 06’W, 144 m below sea level). The pruning treatments for the one-year-old wood were:

1. No pruning

2. Pruning leaving five primary cane

3. Same treatment as (2) and cutting the top 10 cm of the primary cane.

A randomized complete block design with five replications was used.

The number of the primocane developed during the summer was higher in the pruned than unpruned plants, but without effect on its height. Fruit production was higher in the plants without pruning (0.67 kg/plant for the first date and 0.43 kg/plant for the second), but the harvest speed was the lowest (3.1 kg/h vs. 4.6 kg/h) for the check treatment. Fruit flesh thickness was higher in the pruned plants without affecting other parameters of fruit size. However, fruit quality (dried pulp yield of 25.1 to 26.6%) and fruit weight (1.072 to 1.202 g) were not affected.
 
 

In the 1995 - 1996 growth season, 89 species of insects were sampled in direct association with cultivated Amaranthus hybridus (Amaranthaceae) at Tempe Airport, Bloemfontein in the central Free State province. These species comprise five feeding guilds, i.e., chewers, suckers, predators, parasites, and tourists. The stems, leaves, seeds, and pollen of the plant are severely attacked by several species, of which the most injurious proved to be the amaranth weevil, Hypolixus haerens (Coleoptera: Curculionidae). Both the larvae and adults of these weevils attack the crop, with the endophytic, stem-boring larvae causing the most damage. Dominance structures and prominence values of all the amaranth insects were analyzed and three phytophages, viz.Astylus atromaculatus (Coleoptera: Melyridae), a Lygus sp. (Hemiptera: Lygaeidae), and an unidentified Coreidae (Hemiptera) species, and a predator Hippodamia variegata (Coleoptera: Coccinellidae) proved to dominate.

An intricate weevil species complex comprising four Baris spp., in addition to three Lixini spp., a single Ceutorhynchini sp., and a single Aponinae sp., are associated with amaranths. Investigation into the feeding preferences of these species revealed supplementary information concerning weevil life-cycle traits that should have noteworthy implications for amaranth cultivation.
 
 

The diversity within and invasion tempo into a vegetable amaranth monoculture of ‘terrestrial’ insects and other arthropods was studied for a period of eight months (November 1995 - June 1996) by means of a pitfall trapping program at a site 20 km northeast of Bloemfontein in the central Free State province of South Africa. Analysis of trap material yielded a diversity of 221 species, of which Coleoptera formed the dominant order with 127 species. Feeding guilds were also analyzed so that predators, which, together with parasites, form the potential candidates for biologically curbing insect herbivore damage to the plants could be identified.

Correlation of species diversity within guilds showed that predators consisting of Dermaptera (i.e. Forficulidae), Coleoptera (i.e. Cicindelidae, Carabidae, Coccinellidae, Histeridae, Staphylinidae and Anthicidae), Hymenoptera (i.e. Formicidae), and Araneae constitute 96 species (43.4%) of the total recorded, whereas phytophages (i.e. Coleoptera, Isoptera, Orthoptera, Thysanaptera and Hemiptera) constitute 94 species (42.5%). An approximately 1:1 ratio, thus exists between these two guilds, reflecting aspects of insect guild structure on cultivated plants that need further investigation.

The study site is, amongst others, surrounded by patches of natural veld and fallowland and the invasion tempo from each of these areas into the monoculture was high (i.e. 102 spp. and 13,419 individuals; and 87 spp. and 511 individuals, respectively). This phenomenon leads to the notion that such undisturbed marginal areas could act as insect reservoir refuges during periods of unfavorable environmental conditions. In this study, such a scenario could explain the high predator incidence. This also ensures early predator availability in the following growth season, bypassing the time lapse involved in population buildup, which is unavoidable under conditions of standard cultivation practices.
 
 

Recently, a novel method for producing antioxidants from Rosemary (Rosnox) was developed in Israel by the Analit Extracts Company. The antioxidants are used for extending the shelf life of products that contain oils or fats (food and cosmetic products), for preventing oxidation through assimilation into the semipermeable wrapping, as an addition to health foods, etc. The advantages of these materials over other existing antioxidants in the market today are the fact that they are natural, no danger to humans, inexpensive, and with improved effectiveness. These materials produced from Rosemary leaves in such a manner are unique.

Rosemary, a perennial Labiate plant, is generally grown in Israel in small fields of up to half a hectare per farmer and is used only as fresh spice branches. Producing enough raw materials for obtaining the antioxidants requires development of a large-scale cultivation of Rosemary or to rely on imports.

To get the maximum amount of antioxidants, we must have maximum dry matter yield and high concentration of the active materials. Therefore, the first stage was to select a line that embodies the highest concentration of antioxidants, approximately three times that of the standard lines and of imported Rosemary. The second stage of the agricultural work tested the following:

What are the best harvest dates for achieving the maximum yield of active materials?

What is the effect of plant population and irrigation amounts on yield?

Does leaf age have any significance on the concentration of active materials?

Hand-harvesting at different dates, sun-drying and hand-separating of the leaves, confirmed that the active components increased relative to the amount of water applied. As the harvest date was delayed, the plants became woody and the leaf percent of total vegetative material decreased. There was no effect of plant population on yield or on active material concentration.

An additional examination included hand-harvest according to height: the upper half and the lower half the plants with the same irrigation and population. The highest concentration of active materials was in the higher and younger part of the plant. Thus, harvesting young, fresh plants will produce higher vegetative yield, higher concentration of active materials and greater total yield of active materials per field unit. Irrigation of Rosemary (500 mm/y plus rainfall) is necessary, in the geographic region where the trial was conducted. Harvest can be made in early spring and toward the end of the summer. Plant population should be approximately 50,000 plants per ha. Field cost can be reduced by direct planting of cuttings 10 to 15 cm long obtained from the top of the plant.
 
 

For many years, the production of macabo cocoyams (Xanthosoma sagittifolium. (L.) Schott) declined significantly in Cameroon and other macabo producing countries due largely to a root rot disease caused by Pythium myriotylum. This plant species is known to be an important food crop for more than 400 million people worldwide, especially in the tropics and subtropics. Between 1986 and 1994, the United States Agency for International Development (USAID) and the Government of the Republic of Cameroon (GRC) funded a Root and Tubers Research Project (ROTREP) in Cameroon. The main objective of the projects was to develop tolerant/resistant varieties with acceptable agronomic and sociological characteristics. Assemblage of cocoyam germplasm from different agroecological zones of Cameroon was a major part of the breeding program. Additional accessions were collected from other locations including Gabon, Ghana, and Puerto Rico.

Initial collections resulted in the identification of three types of cocoyams, "Yellow," "White,"and "Red." A fourth type "Jinika" was identified in later collections. All assembled genetic materials were then evaluated for growth and yield characteristics, overall yield, composition, and most important, their reaction to root rot disease in the field. Studies were also conducted on several aspects of the floral biology of the species and subsequently, the hybridization success among the different types of cocoyams was determined.

A total of 236 accessions were collected. As would be expected, significant differences were found among accessions for petiole length; leaf, petiole and tuber protein content; tuber dry matter content, marketable cormel weight, seed size and 100-seed weight, and reaction to the root rot disease. Hybridization resulted in the production of 10,132 seeds from the "white" x "white" and "white" x "red" crosses. However, virtually no viable seeds were produced from the "white" x "yellow" or "red" x "yellow" crosses. These results indicate that there may be different ploidy levels for the various types of cocoyams with resultant gynodioecy and incipient speciation in the center of diversity for this species. We also found that a fungicide, Ridomil plus 72, was very effective in controlling the disease, but its cost may be prohibitive for the small-scale farmer. Therefore, a combination of cultural management and fungicidal application should enhance local production until tolerant/resistant cultivars are developed and released by the cocoyam breeders.
 
 

The increased consumption of new and exotic vegetables of tropical origin associated with the growing ethnic population in the U.S. has stimulated great interest for research among groups in the agricultural and scientific community. Tropical exotic and specialty green leafy vegetables are one major group of horticultural crops given attention in the past national symposia on new crops. These crops are mainly grown and consumed in the tropics providing most of the nutrients, particularly minerals and vitamins to the population. During the past five to eight years, the U.S. imported significant amounts of tropical green leafy vegetables and this trend will likely continue. Some of these crops can be grown in the U.S., but factors such as scarcity of seeds and planting materials coupled with inadequate information on cultural management practices, limit the production of these crops. The U.S. Virgin Islands has an ideal climate for growing tropical green leafy vegetables and production of these crops offers alternative marketing opportunities for the sluggish economy. Alternative crops, tropical and specialty greens will have good market potential to meet increasing demands in the U.S. Local growers will have better market advantage in producing these crops over common vegetables such as tomatoes, lettuce and cucumber because growers cannot compete for lower market price of these vegetables coming from the mainland U.S.

Research and development efforts on crop management and production practices for tropical leaf vegetables have been small. The objectives of this study are to: 1) collect and evaluate germplasm of minor tropical green leafy vegetables; 2) evaluate response of germplasm to growing environment; 3) develop sustainable crop management practices and cropping systems for improving yields and market potential; and 4) maintain germplasm collection of promising species for future research.

Over the past two years, close to 80 species and cultivars were collected and some have been field evaluated for growth, response to environment, and productivity. In 1996-97, 54 species and cultivars consisting of Amaranthus sp., Celosia argentia, Basella sp., Corchorus sp., Ipomoea sp. and Brassica sp. (Chinese cabbage and mustard) were field evaluated in replicated and non-replicated trials. Data were collected on leaf area index (LAI), plant height or vine length, fresh leaf and dry matter yields, flowering, pest and disease damage, and seed production. Most cultivars in the Amaranth group have poor plant vigor and were susceptible to damage by cutworms and leaf rollers (Pyralidae sp.). Seed head formation was apparent in Amaranth sp., Celosia sp., and Basella sp., but not in the Brassicae sp. (Pakchoi, mustard and collard). The Brassicae sp. was more productive than others yielding more than 4,000 g m^-2 of edible leaves, which is equivalent to 100-200 g m^-2 d^-1 of edible yield. High yields of this species are attributed to higher LAI, early and more frequent harvests compared with other species.

The trials indicate that under Virgin Islands conditions, the Brassicae sp. including the Oriental greens show potentials for adaptability and higher productivity. Crop management trials including plant spacing and fertilizer application are in progress to improve the yield of traditional species such as the local Amaranth, Basella sp., Corchorus sp., Celosia sp., and Ipomoea sp.
 
 

In 1993, The PawPaw Foundation (PPF) and Kentucky State University (KSU) embarked on a joint venture to evaluate many commercially available named pawpaw [Asimina triloba (L.) Dunal] cultivars and PPF’s advanced selections within and outside its native range.

Orchards for the Regional Variety Trial (RVT), consisting of 300 trees each, will be planted in 18 different locations from Fall 1995 through Spring of 1999. At each RVT site, eight replicate trees of each of the 28 grafted scion varieties will be tested in a randomized complete block design. Named varieties secured for testing include Middletown, Mitchell, NC-1, Overleese, PA-Golden, Sunflower, Taylor, Taytwo, Wells, and Wilson. The other 18 clones to be evaluated originated in PPF orchards at the University of Maryland Experiment Stations at Wye, MD, and Keedysville, MD. Seedling trees from local native sources were planted around the perimeter as a buffer against edge effects and to allow comparisons with local germplasm.

Identical orchards of the RVT are located in the following states: AR, IN, IA, KY (2 sites), LA, MD, MI, NE, NY, NC, OH, OR, SC, and TN (2 sites), the Chinese Academy of Forestry, Beijing, China, and the Chinese Academy of Sciences, Wuhan, Hubei, PRC. An orchard of nonidentical design is located in Tallahassee, Florida. Variables being studied in the trial include climate, culture, pests, growth, flowering, yield, and fruit characteristics.

Trees will be evaluated for several years for yield, year-to-year consistency, regional suitability, etc. At the end of the trial period, regional recommendations will be made. First-year field data will be presented and discussed.
 
 

In Namibia, there are interesting wild members of the Cucurbitaceae that deserve special recognition for the contributions they might make to watermelon breeding. Citrullus ecirrhosus is an arid-zone loving perennial plant. It has recurved leaves along the margins that appear ribbed from above. The leaves have stomata on the top and bottom. The fruits are exploited by the bushmen for their seeds.

Citrullus lanatus is the other species. The wild members of this species have leaves with the top surface exposed. They inhabit slightly wetter areas of the dunes compared with the previous species. The fruit is greenish inside and has oil and protein rich seeds, which are also consumed by the bushmen. The flesh of both species is inedible due to the presence of cucurbitacins. These are very bitter and poisonous. The first species would seem to be suitable for providing drought tolerance. The wild Citrullus lanatus appears useful for providing green flesh to the cultivars. In Namibia, some natives cultivate watermelons, which have green parts on the edible flesh. Remarkably, the green fleshed character has not yet appeared in western or eastern cultivars.

Finally, efforts should be made to create exports based on Acanthosicyos horridus, a cucurbit that grows and contributes to the seawards dunes in Namibia. The fruit is bitter when young, but lose their bitterness when mature. At that time, the white fruit flesh changes into a mandarin-colored flesh, sweet, aromatic, and a food-reserve-rich flesh with highly nutritious oily seeds. The bushmen process both the flesh and the seeds. Opportunities exist for its use in ice cream manufacture, chocolate fillings, rice pudding, freeze-dried chocolate, and cake flavorings. The seeds make excellent pumpkin or watermelon seed substitutes. They are thicker than these competitors and have a fine flavor.
 
 

Pointed gourd (Trichosanthes dioica Roxb) is a tropical vegetable crop widely cultivated in the eastern part of India. It is commonly known in India by the name parwal. The plant is a creeping vine producing dioecious flowers and 5-16 cm long pepo fruits. It is a semi-perennial with a useful fruiting life of several years. The crop is usually propagated by vine cuttings or root-suckers. Its seed is not suited for propagation because of poor germination and difficulty in identifying the gender of vines before flowering. There is a niche market for the pointed gourd in the United States among immigrants from the Indian subcontinent. Because this vegetable is reputed to lower blood sugar, it may also attract buyers who need to lower their blood sugar. However, pointed gourds are currently not grown in the United States. Limited quantities are occasionally imported from the Caribbean and sold for premium in the metropolitan speciality vegetable markets. A need exists to develop an indigenous source. Pointed gourd may not be suited for production on large acreage because of the labor needed to pick the small-size fruits. However, small farms and part-time growers located close to metropolitan cities may find it economically rewarding to produce this crop.

This study was initiated during 1995 to determine the potential of producing pointed gourd in the temperate North American climate. Vines for establishing the study were procured from the Narendra Deva University of Agriculture and Technology, Faizabad, India with the help of the National Germplasm Resources Laboratory, Beltsville, Maryland. Vine cuttings were planted in pots in a greenhouse in September 1994 and kept under mist until roots formed. Plants were transferred to the field in April 1995. Field planting consisted of five female and one male row each 12 m long. Intra-row and inter-row spacings were 1.5 m and 1.8 m, respectively. Vines were trained on 3 m high fence-wire trellises. During the fall, vines were cut to ground level and covered with pine-straw for the winter. Data on winter survival rate, fruit number, and fresh and dry fruit weight were collected.

Findings during 1996 and 1997 are reported. The winter plant survival was 100%. Harvesting lasted for 15 and 17 weeks during 1996 and 1997, respectively. In 1996, the total number of fruits per plant, fresh fruit weight per plant, and total dry fruit weight per plant were 190, 5.0 kg, and 0.46 kg, respectively; and for 1997, 254, 6.5 kg, and 0.65kg. When the weight of fresh fruits per plant was converted to yield on a land area basis, it was similar or better than yields reported in the literature. Therefore, these results suggest that pointed gourd can be produced successfully in the southeastern United States.
 
 

The cultivation of pistachio nuts in South Africa is a relatively new enterprise with vast economic potential. However, it is inevitable that pistachio cultivation will be faced with numerous disease problems in time. Many of the disease causing microorganisms of cultivated pistachio in other parts of the world will inevitably make their presence felt in South Africa as will new pathogens never recorded. The need to establishing a disease management program for this crop is clearly evident. The present investigation was undertaken to characterize the fungal microflora associated with diseased pistachio trees over six years.

In the spring of 1992, dieback of three-year-old Pistacia vera grafted onto P. atlantica rootstocks was first observed in trial plantings in the district of Prieska, Northern Cape. Dying trees (foliage appearing chlorotic and wilted) were scattered throughout the plantings. Examination of these trees revealed cankers on the lower stems in the vicinity of the graft. A study was undertaken to characterize the fungi present and to test their virulence to three important Pistacia species.

Isolations from margins of diseased tissue onto malt-extract agar consistently yielded black fungal colonies and pycnidia bearing mature conidia. These were identified as the Sphaeropsis anamorph of Botryosphaeria obtusa. Branches, 5 mm in diameter, of P. atlantica, P. vera, and P. integerrima developed mean cambial lesions of 53, 51, and 15 mm, respectively, 14 days after artificial inoculation with mycelium of B. obtusa. Wounding of branches prior to inoculation resulted in larger cambial lesions (P < 0.05). As far as we could determine, there were no previous published reports of B. obtusa associated with disease of cultivated pistachio trees.

In the past five years, one- and two-year-old rootstocks of P. atlantica and P. intergerrima were frequently observed with cankers on the lower stem during the spring months. Diseased trees were examined in the laboratory for potentially pathogenic fungi. Of the cankers examined during this period, the most common fungi isolated were B. obtusa (55%), five Fusarium species (25%), Fusicoccumaesculi (anamorph of Botryosphaeria dothidea) (10%), Cytospora sp. (5%), and other fungi (5%). Other fungi included Alternaria alternata, Phoma sp., and Chaetomium sp. In inoculations conducted in the glasshouse, only F. aesculi proved to be pathogenic to P. atlantica. Mean lesion lengths of 40.6 mm were measured eight weeks after stem inoculations of potted plants that had a mean stem diameter of 6.7 mm. The consistent occurrence of B. obtusa and B. dothidea with diseased pistachio trees justifies establishing an intensive disease management program for pistachios in South Africa.
 
 

To determine the key aroma compounds of the dried fruits of Xylopia aethiopica, high resolution gas chromatography/olfactometry (HRGC/O) was applied to the aroma concentrate obtained by high vacuum distillation of an ether extract of the fruit material. Twenty-eight odor-active compounds were detected at the sniffing port and fully identified by using reference odorants. They were then ranked based on their flavor contribution by means of aroma extract dilution analysis (AEDA), a technique combining instrumental-chemical analysis and sensorial evaluation.

According to their high flavor dilution factors, 19 of the 28 volatiles were elucidated with the highest aroma activity. Linalool (flowery), trans-b-ocimene (flowery), a-farnesene (sweet, flowery), b-pinene (terpeny), vaniline (vanilla-like), and 3-ethylphenol (smoky, phenolic) were unequivocally identified as the character impact odorants by HRGC/mass spectroscopy and by comparison of the chromatographic, spectroscopic as well as sensory data with those of the synthetic reference compounds. Implications of these novel findings in food, medicinal, and perfumery applications are discussed.
 
 

Yacon is a species of Asteraceae family originating in the Andean areas of Colombia, Ecuador, Peru, Bolivia and northwest Argentina at altitudes between 2,000 and 3,100 m. It is also known as "aricoma" or "jicama" in Peru and Ecuador, and "yacon strawberry" in United States. The species was introduced in Brazil about 1991 in Capão Bonito, State of São Paulo by Japanese immigrants who used the leaves and tuberous roots for treating diabetes and to lower blood cholesterol.

The perennial plant has a complex root system consisting of three parts: the tubers are rich in fructans and nondigestible fibers and can create a new plant; the absorbing and structural roots; an