Cover crops offer an excellent source of nutritional requirements for production of vegetables in sustainable agricultural system. By using this concept, field experiments were conducted in l998 at three locations in Virginia; Petersburg, James City, and King and William County, and five cover crop treatments; Hairy Vetch (HV), Crimson Clover (CC), HV+Rye, CC+Rye, and a conventional bare-ground control were used for their potential support of nutritional requirements for production of a seedless watermelon crop. The results indicated that the yield levels of seedless watermelon following cover crop treatments had significantly higher number of fruits per acre and the crimson clover treatment had higher fruit size in one of the sites (King William County) as compared to the other four treatments and two sites suggesting that cover crop/crops alone have the potential to support nutritional requirements for seedless watermelon to sustain production, thus becoming a viable and profitable alternative to using inorganic nitrogen source. The effects of cover crops on chemical composition of seedless watermelon were generally not significant. The results also indicated that watermelons produced using sustainable crop production methods are comparable to those produced using conventional methods. Our studies support using seedless watermelon as a viable alternative and high-value cash crop for Virginia farmers' especially tobacco growers, other small-scale producers, and limited resource farmers.
M. Rangappa and H.L. Bhardwaj
W. Mersie, T. Mebrahtu and M. Rangappa
Plant introductions of Phaseolus vulgaris L. were grown from seed in a growth chamber and exposed to 0, at 0.6 μl·liter-1 for 2 hours. Plants were assessed for their response to O3 by evaluating percent leaf injury. Of the 410 introductions tested. 17 insensitive. 370 sensitive. and 23 highly sensitive plant introductions were identified.
M. Rangappa, A.A. Hamama and H.L. Bhardwaj
Although there is increasing interest in reducing the use of nitrogen (N) fertilizers due to the potential of unused N causing pollution of surface and groundwater, N is a major nutrient for plant growth. Our objective was to determine the potential of using winter legume cover crops to meet the N needs of seedless watermelon (Citrullus lanatus), a potential cash crop for farmers in Virginia. Fruit number, fruit weight, fruit yield, and fruit quality traits (flesh to rind ratio, water content, total soluble solids, sugar content, and pH) of seedless watermelons were evaluated in replicated experiments in Virginia at three locations during 1997-98 and two locations during 1998-99 following cover crop treatments consisting of crimson clover (Trifolium incarnatum), hairy vetch (Vicia villosa), crimson clover + rye (Secale cereale), hairy vetch + rye, and a bareground control treatment that received 100 lb/acre (112 kg·ha-1) of N. At all five locations, the bareground control treatment resulted in fewer fruit [1803 fruit/acre (4454 fruit/ha)], lower fruit weight [9.8 lb (4.5 kg)], and lower fruit yield [8.9 tons/acre (20.0 t·ha-1)] compared to the four cover crop treatments. The crimson clover + rye and hairy vetch treatments resulted in highest numberof fruit [2866 and 2657 fruit/acre (7079 and 6563 fruit/ha), respectively], whereas the highest fruit yield was obtained following hairy vetch [21.2 tons/acre (49.8 t·ha-1)], hairy vetch + rye [20.3 tons/acre (45.5 t·ha-1)], and crimson clover + rye [19.6 tons/acre (43.9 t·ha-1)]. Cover crop treatments did not affect the quality of watermelon flesh. The seedless watermelon fruit averaged 1.4 flesh: 1 rind ratio, 90% water content, 9.5% total soluble solids, 8.0% sugar, and a pH value of 5.9. These results indicated that legume cover crops, such as crimson clover and hairy vetch, can be successfully used to produce seedless watermelons, in a no-till system, without any use of N fertilizers with dryland conditions.
M. Rangappa, H.L. Bhardwaj and A.A. Hamama
A collection of 35 mint (Mentha spp.) lines was evaluated during 1996 for fresh and dry yield, percentage of leaves, leaf moisture, and stem moisture to study suitability for fresh markets. These lines were categorized based on geographic origin (domestic vs. foreign), ploidy level (diploid vs. polyploid), mint type (peppermint vs. spearmint), and genetic makeup (pure lines vs. hybrids), and statistical comparisons were made between these categories. Fresh yield and proportion of fresh leaves in the total harvest were affected by type and genetic makeup of mint accessions. Spearmint had significantly greater yield than peppermint (4.1 vs. 2.5 kg/m2) and higher proportion of leaves (69% vs. 63%). Species had higher fresh yield than hybrids (4.1 vs. 2.7 kg/m2) and higher proportion of leaves (69% vs 65%). Domestic accessions, peppermint, and hybrids had significantly higher leaf moisture than foreign accessions, spearmint, and species (26% vs. 22%, 28% vs. 23%, and 27% vs. 24%, respectively). None of the categories affected moisture content in the total plant harvest or stems. Further details of these data will be presented and discussed.
M. Rangappa, McArthur Floyd, Val Sapra, Jagmohan Joshi, Thomas Carter and M. R. Reddy
A USDA/OICD sponsored agricultural research team visited the Republic of China (Taiwan) and the People's Republic of China (PRC) in 1990 to gather information regarding soybean utilization and to increase genetic diversity of the soybean crop through new germplasm collections. A total of 25 new soybean accessions were collected and brought to the Virginia State University, Petersburg, VA, one of the OICD sponsored team participants. In accordance with the U.S. policy on the New Germplasm Collection, part of the seed of each accession was sent in original packs to USDA Soybean Germplasm Collections, University of Illinois, Urbana, Ill. Limited seed increase was done in the greenhouse and one 10m long observational row of each accession was grown at VSU Research Station in 1991. Seed traits, plant agronomic characteristics, insect pest, and disease pathogen reactions were observed and documented. Chemical analysis for nutritional quality, antinutritional factors, and biochemical components of green seeds and pods at R-7 stage and mature seeds of each accession are underway and those values will be compared with existing commercial cultivars, advanced breeding lines, and plant introductions.