Evaluation of Soybeans in Maturity Groups I-IV for Resistance to Heterodera glycines.
Forty-seven private and public soybean (Glycine max) cultivars in maturity groups I, II, III, and IV were evaluated in the field for resistance to Heterodera glycines race 3 and race 4 at two sites, Kilbourne and Urbana, Illinois. The soil at Kilbonrne was an irrigated sand infested with race 3. The soil at Urbana was a nonirrigated silty clay loam infested with race 4. Yield of nematode-susceptible controls was reduced at both locations, and yield differences were observed among the other cultivars. Soybeans grown in sand yielded less than the soybean grown in silty clay loam. Although populations of H. glycines recovered at planting were lower at Kilbourne than at Urbana, a greater percentage of loss in yield was associated with the sand at Kilbourne. Several soybean cultivars had a high level of resistance to both populations of H. glycines.
Soybean Seed Yield Performances under Different Cultural Practices
This study was carried out to investigate the yield response of 2 soybean (Glycine max (L.) Merrill) cultivars to different planting dates and plant populations and to examine the relationships of seed yield with leaf area index (LAI) and total dry matter (TDM) during the vegetative and reproductive periods for planting dates, plant populations, and cultivars. Two soybean cultivars, A-3127 (early maturity group, MG-III) and 1530 (late maturity group, MG-IV), were planted in 2 planting dates; mid-April and mid-May during 2005 and 2006 at high (660,000 plant ha-1) and low (330,000 plant ha-1) plant populations. Plantings in mid-April increased seed yield by about 10.0%-13.5% compared with mid-May plantings. High plant populations produced 17.7% higher seed yield than the low population. Seed yield of the late maturity cultivar was more than that of the early maturing cultivar. Significant and positive relationships between seed yield and LAI were evident for planting dates at all growth stages in 2005 and 2006. Seed yields at high and low plant populations were negatively and significantly correlated with LAI at vegetative stage (V5), but positively and closely related to LAI at reproductive stages (R4 and R6) in both experimental years. The relationships between seed yield and LAI with early and late maturity cultivars were significant and positive at all growth stages except the V5 growth stage in both 2005 and 2006. Seed yield was positively and significantly correlated with TDM at all growth stages for planting dates, plant populations, and cultivars.
Evaluation of antioxidants by a rapid polarographic method
A simple, rapid, precise, and reproducible method and an adaptable apparatus for polarographic measurement of lipid peroxidation and antioxidant activity is described. This method measures antioxidant activity within a few min time as compared to the hours or days needed for several widely used methods. Peroxidation rates were measured for different lipids as a function of amount of lipid, and amount of biocatalyst. The method is applicable to the detection and measurement of the antioxidant effects exhibited by weak antioxidants and has been satisfactorily used for the measurement of the antioxidant activity of different concentrations of powerful antioxidants.