Genotype-Environment Interaction Studies Over Seasons for Kernel Yield in Maize (Zea mays L.)
Abstract
Forty five single cross hybrids derived from 10 inbred lines of maize were tested for kernel yield across three seasons viz., rabi, summer and kharif adopting AMMI model to assess the G × E interaction and to identify the stable hybrids for kernel yield. Seasons were found to contribute to the variations in performance of hybrids indicating that unpredictable seasonal conditions are one of the constraints in selecting superior and adaptable hybrids. The hybrids viz., BML 6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × Heypool, DFTY × PDM 1452 and Heypool × PDM 1474 across seasons recoded significantly higher kernel yield over general mean. The first two interaction principal components viz., PC 1 (74.00 %) and PC 2 (16.00 %) of GGE-biplot analysis explained 90.00 % of total variation caused by genotype × environment interaction. Hybrids viz., DFTY × Heypool, BML 15 × PDM 1452 and Heypool × PDM 1474 were the vertex hybrids or winners indicating that they are the best performing or responsive hybrids. Summer season was found to be the most discriminating season in culling the unproductive ones and also to save time and expenditure. Kharif and rabi seasons were the most representative testing seasons for kernel yield. Hybrids viz., BML 2 × DFTY, BML 2 × Heypool, BML 6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × PDM 1452, Heypool × PDM 1474 and PDM 1452 × PDM 1474 were more stable as well as high yielding, whereas DFTY × Heypool, BML 15 × PDM 1452, BML 15 × Heypool and DFTY × PDM 1474 were more variable but high yielding. The hybrids BML 6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × Heypool and Heypool × PDM 1474 were located near to ideal genotype with high mean and stability and could be ranked as desirable hybrids for kernel yield.
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Introduction
Maize is an important cereal crop worldwide and is ranked third after wheat and rice for its nutritional quality and uses Cassamon,; Ali et al, 2014. It is mostly used as a food, feed, forage, green fuel, vegetable oil and starch and is the backbone of the poultry feed industry. Kernel yield is a quantitative character, which depends on several yield contributing factors. Genotype × environment interaction reduces the association between the phenotype and genotype which in-turn reduces the selection response (Yan and Kang, 2003). Genotype–environment interactions may cause inconsistencies in genotype ranking across environments. Therefore, testing of identification and interpretation of G × E interaction is essential to make genetic progress (Kang, 2002 and Crossa, 2012). In the process of breeding, newly developed hybrids should be tested in multiple environments to determine the performance and stability before their commercial release. Multi environment trials aids in identification and recommendation of superior stable genotypes in mega environments. Seasons were found to contribute to the variations in performance of hybrids indicating that unpredictable seasonal conditions are one of the constraints in selecting superior and adaptable hybrids. AMMI model combines analysis of variance for the genotype and environment main effects with principal components analysis of the G × E interactions (Gauch and Zobel, 1996). It is useful in statistical analysis of comparative experimental yield clarify the effect of genotype in the environment, patterns and relationship of genotypes and the environment and also for improving the precision of yield estimation (Zobel et al, 1988; Crossa et al., 1990 and Annicchiarico, 2002). The present study was carried out to identify superior experimental hybrids as well as to select the best environment (Season) for testing hybrids developed in the maize breeding through AMMI biplot method.
Conclusion
Seasons were found to contribute to the variations in performance of hybrids indicating that unpredictable seasonal conditions are one of the constraints in selecting superior and adaptable hybrids. The hybrids viz., BML 6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × Heypool, DFTY × PDM 1452 and Heypool × PDM 1474 across seasons recoded significantly higher kernel yield over general mean. Hybrids viz., DFTY × Heypool, BML 15 × PDM 1452) and Heypool × PDM 1474 were the vertex hybrids or winners indicating that they are the best performing or responsive hybrids. Summer season was found to be the most discriminating season in culling the unproductive ones and to save time and expenditure. Kharif and rabi seasons were the most representative testing seasons for kernel yield. Hybrids viz., BML 2 × DFTY, BML 2 × Heypool, BML6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × PDM 1452, Heypool × PDM1474 and PDM 1452 × PDM 1474 were more stable as well as high yielding. Hybrids close to the ideal genotype were ranked as the ones with high mean and phenotypic stability. The hybrids viz., BML 6 × PDM 1474, BML 7 × DFTY, BML 15 × PDM 1474, DFTY × Heypool and Heypool × PDM 1474 were located near to ideal genotype with high mean and stability and could be ranked as desirable hybrids for kernel yield.
