GENOTYPIC PERFORMANCE OF 15 MAIZE CULTIVARS FOR STEM BORER RESISTANCE IN OWERRI WEST, SOUTH EASTERN NIGERIA

One of the major biotic constraints to increased maize production in Nigeria is the parasitic insect, stem borers which cause yield losses ranging from 50 – 75%. Genetic diversity for a range of agronomic and resistance attributes with 15 local maize collections from Abia and Imo states of Nigeria were evaluated in field trials in randomized complete block design (RCBD) with five replications in late season of 2010 and early season of 2011. Data collected from the evaluations were subjected to both uni- and multivariate analyses. Rank Summation Index (RSI) identified 3 best genotypes (Um-Dik, Oka-Aki and Oha-Gbem with RSI values of 58, 61 and 71 respectively) representing top 20% of the total as resistant. Out of the two principal component functions obtained, the two had significant (p = 0.05) values accounting for over 98.81% of the total variation. Also, out of a total of five discriminant clusters formed, the clustering pattern revealed that clusters; I, II and IV comprise of early emerging (52 days to silking), high productive (3.33t/ha) and resistant (5.83%) genotypes respectively. The correlation analysis result showed that the grain yield had significant and positive relationships with plant height, ear at harvest, ear per plant and field weight.