Simultaneous Selection Index as a Tool for Identification of Stable High Yielding Maydis Leaf Blight Resistant Maize Prebreeding Lines
Abstract Maize is a crop possessing high adaptability however, large differential genotypic responses have been reported when evaluated under multiple environments. Using randomized complete block design with two replications a total of 169 teosinte derived maize backcross inbred lines (BILs) were evaluated in three different environments namely, E2, E4 and E6 for maydis leaf blight (MLB) resistance and grain yield. Out of these, 73 BILs were identified displaying resistance to MLB in at least one of the environments and were subjected to additive main effect and multiplicative interaction (AMMI) analysis and genotype and genotype X environment (GGE) biplot analysis for identification of lines showing stable and high MLB resistance and grain yield. Highly significant effects of genotype, environment and genotype X environment interaction (GEI) were observed for both the traits studied. AMMI ANOVA for percent disease index (PDI) revealed that highest percentage of total sum of squares (SS) was attributed to GEI (40.55%) while 32.86% and 26.59% was contributed by genotype and environment, respectively. For grain yield largest contribution of 68.02% towards SS was done by genotype component followed by GEI (17.50%) and E (14.48%). GGE biplot analysis identified two mega environments for both PDI (E2, E4/E6) and grain yield (E2/E4, E6). Based on AMMI stability value (ASV), genotype MT-90 (32) was observed to be most stable for PDI. While for grain yield highest stability was displayed by genotype MT-83 (28). Simultaneous selection index (SSI) helped in identification of ten stable high yielding MLB resistant genotypes namely, MT-120 (45), MT-14 (2), MT-166 (62), MT-148 (55), MT-190 (72), MT-37 (9), MT-19 (3), MT-114 (42), MT-77 (27) and MT-94 (35) which could be used in future breeding programmes either as donor of MLB resistance and grain yield or after combining ability analysis these genotypes could be used as parents for development of superior yielding MLB resistant hybrids.