Muddappa Rangappa

Effects of ozone on soybean resistance to the mexican bean beetle (Epilachna varivestis mulsant)

Abstract Two soybean [Glycine max (L.) Merr.] cultivars, Forrest and Essex, were exposed to incremental levels of O3 in open-top field chambers during the 1986 growing season. Treatments consisted of chambers receiving carbon-filtered air or non-filtered air to which either 0.00, 0.03 or 0.06 ppm (μl/l)O3 was added continuously for 7 hr/day. After 3 weeks of exposure, the feeding preference of Mexican bean beetle (MBB) adults (Epilachna varivestis Mulsant) was determined by placing plants in a carbon-filtered chamber enclosed by an aluminum screen. Defoliation was visually determined after the MBB had fed for 6–8 days. Leaves from the remainder of the plants were brought to the laboratory and fed to MBB larvae. The larvae were reared in plastic boxes until pupation, and developmental time, pupal weight and mortality were determined. Visible O3 injury increased significantly with increasing O3 concentration and Forrest was significantly more sensitive than Essex. No cultivar differences were found in MBB adult feeding preference, but defoliation increased significantly with increasing O3 concentration. Results, although not as definitive as in the feeding preference study, indicated that MBB larvae tended to weigh more and develop faster on ozonated foliage. Implications of this pollutant × pest interaction are discussed relative to its potential impact on crop production.

Vernonia oilseed production in the mid-Atlantic region of the United States

Abstract Epoxidized oils, manufactured by chemical epoxidation of fats and vegetable oils such as soybean [ Glycine max (L.) Merr.], are useful in reformulation of oil based (alkyd-resin) paints to reduce emissions of volatile organic compounds that contribute to production of smog. Other potential markets for epoxy fatty acids include plasticizers, additives to polyvinyl chloride, polymer blends and coatings, cosmetic, and pharmaceutical applications. Currently, no oilseed crop has been commercialized as a source of natural epoxidized oils. However, Vernonia galamensis (Cass.) Less. has been identified to have potential for domestication as a new industrial oilseed source of natural epoxy fatty acids. The main objective of this research was to evaluate feasibility of vernonia production in mid-Atlantic region of the United States. Specifically, we wanted to evaluate available vernonia germplasm for seed yield, oil content, and oil quality, and to determine suitable production practices. The seed yield (kg/ha) in field experiments conducted from 1994, 1995, and 1996 at Randolph Farm of Virginia State University (37°15′N and 77°30.8′W), with a selected group of vernonia lines, ranged from 490 to 1288, 494 to 1394, and 1070 to 1934, respectively. Oil content ranged from 30.2 to 36.7% and 32.1 to 39.2%, respectively for 1995 and 1996 and the vernolic acid content ranged from 68.9 to 74.7% and 69.1 to 75.6%. A significant positive correlation ( r =0.34) between oil content and vernolic acid content indicated that both these characteristics could be improved simultaneously. The highest seed yield was obtained with 100 kg N/ha. A pre-plant-incorporated application of Trifluralin herbicide at 0.5 kg/ha a.i. did not reduce vernonia stand establishment. Seedhead shattering was observed to be a limitation in the evaluated vernonia germplasm. These results indicate that commercial vernonia production in Virginia and other areas in the mid-Atlantic region of United States may be feasible.

Nutrient composition and anti-nutritional factors in selected vegetable soybean (Glycine Max [L.] Merr.)

The genetic variation in the nutrient composition and anti-nutritional factors of 17 vegetable soybean genotypes were determined and a wide variation in protein %, total phosphorus (TPi) and available phosphorus (AP) was found among these genotypes. Variations in Ca, K, Fe, Mn, and Cu were also documented. Variation was also found for trypsin inhibitor (TI) activity and Phytate (PA) content. A highly significant and negative correlation (r=−0.533,P<0.01) was observed between TI and total protein. Strong positive correlation (r=0.90) was also found between TPi and AP. Several genotypes (Sooty, Emperor, Wilson-5, PI 416771, PI 417322) showed good nutritional potential and can be used in the breeding program. High protein %, TPi, and minerals are desirable qualities for vegetable-type soybeans that make it as food with high nutrient density. Studies on the nutritional evaluation of immature vegetable type soybean seeds at different reproductive stages are also underway.

Screening soybean (grain and vegetable) genotypes for nutrients and anti-nutritional factors

Fifty six genotypes of grain-type soybean and 17 genotypes of vegetable-type soybean collections were analyzed for protein and oil content, trypsin inhibitor, and lipoxygenase activities. The protein and oil content ranged from 36.9 to 47.9% and from 13.3 to 23.0% for different accessions in grain- and vegetable-type soybeans, respectively. Trypsin inhibitor and lipoxygenase activities ranged from 22.0 to 47.0 trypsin inhibitor units/mg meal and from 482 to 6265 lipoxygenase units/min/mg meal for grain- and vegetable-type soybeans, respectively. Significant correlations (r=−0.62 and −0.52,P<0.05) were found between protein and oil, and between protein and trypsin inhibitor. A significant positive correlation (r=0.42,P<0.05) was also calculated for oil and lipoxygenase activity. Several genotypes of soybean and vegetable soybean (plant introductions 423905, 417330, 417223, 171451, 200506, 200523, 417124, 227687, 203402, 445842, 203399, 423852, 416771, FC31927, Avoyelles, and Sooty) showed good nutritional potential and may be useful in a breeding program to improve the nutritional quality of soybean. Screening for essential amino acids, fatty acids, and trace minerals for selected genotypes is underway.

Inheritance of ambient ozone insensitivity in common bean (Phaseolus vulgaris L.)

The inheritance of ozone (O(3)) insensitivity in common bean (Phaseolus vulgaris L.) was evaluated using F(2) and F(3) populations under ambient conditions. This study was conducted over two growing seasons (1987, 1988) at Virginia State University, Randolph Research Farm, Petersburg, Virginia. Two populations were obtained by crossing insensitive plant introductions with sensitive commercial cultivars. Ratings on the scale of 1 to 5 (1 = 0 to 20% leaf injury, 2 = 21 to 40%, 3 = 41 to 60%, 4 = 61 to 80%, and 5 > 80%) were made on 160 F(2), F(3) progenies, and parental lines. Population mean injury ratings were recorded and estimates of genotypic, environmental, and phenotypic variances were computed. Estimates of heritability in the broadsense and of genetic advance were calculated for each population using F(2) and family component variance methods. Population means of the F(2) and F(3) progenies were not significantly different from their mid-parent values, suggesting that genetic variance was primarily additive. Broad-sense heritability estimates using F(2) variance method ranged from 51.4 to 70.5% and using family component variance method ranged from 62.1 to 75.6%. In this study, the computed genetic advance values closely parallel those of heritability estimated values. The high heritable nature of insensitivity would indicate that effective levels of insensitivity could be transferred to agronomically superior cultivars in a relatively short time.

Evaluation of Vegetable Soybean Genotypes for Resistance to Corn Earworm (Lepidoptera: Noctuidae)

Petri dish bioassays were used to evaluate terminal foliage from 47 field-grown genotypes of vegetable-type soybean, Glycine max (L.) Merrill, from maturity groups III through VIII, for resistance ...

Response of corn to combinations of atrazine, propyl gallate and ozone.

Abstract Growth chamber experiments were conducted to determine the influence of the air pollutant ozone (O3) [0.2 and 0.3 ppm (v/v)] on the growth of corn (Zea mays L.) treated with the herbicide atrazine (2.5 and 3.5 kg/ha) and the antioxidant propyl gallate (5 and 8 kg/ha). At both concentrations O3 at 0.3 ppm alone reduced dry weights of corn and chlorophyll. Chlorophyll a was more affected than chlorophyll b by O3 at 0.3 ppm alone and in combination with atrazine. Propyl gallate at both rates protected corn against O3 injury. The interaction between atrazine and O3 at 0.2 ppm was additive whereas at 0.3 ppm it was antagonistic. But combinations of atrazine and propyl gallate did not protect corn from O3 injury.

Seed characteristics and nutrient composition of selected beans (Phaseolus vulgaris L.) with different ozone tolerance

Ozone sensitivity, nutritional quality, seed characteristics, and growth habit of beans (Phaseolus vulgaris L.) were evaluated in two seperate experiments. In the first experiment the data showed a significant variation among 34 bean accessions for ozone sensitivity following acute exposure of 18-day-old plants to 0.6 µl/l O3 for 2 hours under environmentally controlled greenhouse conditions. PI-163579, PI-169735, PI-171790, PI-176684, PI-201374, PI-310711, PI-345576, PI-370569, PI-379435, and PI-414831 were identified as tolerant to acute ozone exposures. Protein, oil, starch, sugar, and ash contents in the seed of selected germplasm were determined and no correlation was found between these components and ozone sensitivity. Seed size and growth habit varied considerably among the 34 accessions but were not correlated to ozone sensitivity. In a second experiment, ten accessions, selected from the tolerant ones identified in the first experiment, were subjected to chronic ozone exposure in open-top chambers at 0.04 and 0.08 µl/l concentrations for 7 hours/day 44 days after transplanting. Based on foliar injury and yield reductions, only PI-370569 and PI-414831 were tolerant to prolonged ozone exposure (0.08 µl/l). A significant positive correlation (r=0.83) existed between foliar injury rating from chronic treatments involving 0.04 and 0.08 µl O3/l and acute exposure (0.6 µl O3/1/2 hours). The data indicated that acute ozone exposure can be used to initially screen a large number of bean accessions, however, this is an imperfect indicator of ozone sensitivity with chronic exposure.