Influence of Genotype on the Expression of Host Plant Resistance in Soybean (Glycine Max (L.) Mirrill) to the Major Insect Pests of Soybean in Umudike

Due to low annual production output of soybean grains in Nigeria which was attributed to insect pests infestation, six soybean genotypes were screened for major insect pests resistance in the National Root Crops Research Institute (NRCRI), Umudike. The trials were arranged in the Randomized Complete Block Design with four replicates during 2014 and 2015 growing seasons under the tropical climatic conditions. Analyses were done by pooling over two years due to insignificant genotype Х year interactions. Rank summation index (RSI) results showed that TG Х 1448 (V6) with RSI value of 17 had overall best performance in terms of resistance, yield and other yield related attributes. Result obtained from correlation indicated that grain yield was significantly and positively correlated with pod number per plant (r = 0.907*) and seed number per pod (r = 0.691*). Conversely, significant and negative correlation was recorded between grain yield and number of damage pod per plant (r = -0.616*). Compared to the simple correlation analysis, path analysis of grain yield and its traits demonstrated that pod number per plant and pod length evolved the highest positive direct influence, 1.80 and 0.65 respectively. Hence, selection for these traits could bring improvement in yield and yield components.