ASSESSMENT OF GRAIN SORGHUM (SORGHUM BICOLOR. L) VARIETIES FOR YIELD AND REACTION TO MAIZE WEEVIL (SITOPHILUS ZEAMAIS MOTS) IN SOUTHWESTERN NIGERIA

Abstract

To facilitate the development of high yielding and adaptable sorghum varieties, investigating the stability, adaptation, yield and resistance of sorghum varieties to Sitophilus attack in rainforest and derived savanna agro-ecological zones is highly important before selection. Thus, this research was undertaken to evaluate the performance of some varieties of sorghum in two locations in southwest Nigeria (the Teaching and Research Farm of the Federal University of Technology, Akure, a tropical rainforest zone of southern Nigeria and National Centre for Genetic Resources and Biotechnology (NACGRAB) Ibadan, a derived savanna agro ecological zone. The varieties of sorghum used were obtained from the Federal University of Technology, Akure and ICRISAT. The field experiment was conducted using Randomized Complete Block Design (RCBD) with three replications. The field was marked out and planting was done to evaluate their growth and yield. After harvesting samples from the varieties were stored for three months in plastic containers (250 ml) under natural infestation. Insect infestation was observed after two and three month period. In an experiment, panicles were harvested from the field, data on insect population was taken immediately, and after one week of harvest. Data was taken on seedling emergence count, plant height, number of stands, panicle length, panicle width, panicle weight, 100-seed weight, 1000-seed weight, panicle weight per plot, yield and insect infestation count. The data obtained for each character on the basis of sampled plants were averaged and the mean values obtained were used for statistical analysis. The data collected were subjected to Analysis of Variance (ANOVA) using MINITAB, version 17 statistical package for each location. Mean effects that showed significant F- test were separated using Tukey’s Honest Significant difference (HSD) test at 5% level of probability. Component of variance, heritability and genetic advance were estimated. PBTools software was used to analyze genotypic and phenotypic correlation. Estimates of phenotypic and genotypic variances were computed from the ANOVA. The results from this experiment revealed that the significance (p<0.01) variation existed among the varieties in the traits investigated. Genetic variation also exists among the varieties of the sorghum studied. Across location, high broad sense of heritability estimate was obtained for plant height, panicle weight, panicle weight per plot, 100-seed weight yield and insect infestation. In the study, plant height was positive and significantly correlated with panicle weight per plot and number of stands, panicle weight was significantly correlated with number of stands and yield, and panicle weight per plot was significantly correlated with yield. Consequently, selection for any of these traits could lead to selection for improved grain yield. The results on stored varieties were significantly different for insect infestation character at Akure, but not significantly different in Ibadan. Also, Sitophilus zeamais was predominant among other insect pests on sorghum panicle. It is sorghum’s persistent pest and the likely field to store pests. Conclusively, Chokwe 1 and Macia 3 were identified as the most promising sorghum varieties that can be manipulated for higher yield. NR71182, Chokwe 1 and Zaunalnuwa are the promising ones that had low and moderate insect infestation. These are recommended due to their consistent and superior performances at the two locations. Their cultivation can bring about substantial increase in sorghum production.