Multi-location experiments on maize were conducted from 2016 to 2019 at ten locations distributed across two agro-climatic zones (ACZ) i.e., ACZ-3 and ACZ-8 of Karnataka, India. Individual analysis of variance for each location-year combination showed significant differences among the hybrids; similarly, combined analysis showed a higher proportion of GE interaction variance than due to genotype. Mega-environments were identified using biplot approaches such as AMMI, GGE, and WAASB methodologies for the years 2016 to 2019. The BLUP method revealed a high correlation between grain yield and stability indices ranging from 0.67 to 1.0. Considering all three methods together, the three location pairs Arabhavi-Belavatagi, Bailhongal-Belavatagi, and Hagari-Sirguppa had three occurrences in the same mega-environment with a value of 0.67, and these location combinations consistently produced winning genotypes. Among the common winning genotypes identified, it was G7 during 2016 and 2017 and G10 during 2018 and 2019, based on WAASBY. The likelihood of Arabhavi-Nippani, Hagari-Mudhol, and Dharwad-Hagari occurring in the same mega-environment is minimal because they did not share the same winning genotype, with the exception of a small number of events. Despite being in the same agro-climatic zone, Arabhavi, Hagari, and Mudhol rarely had a winning genotype in common. An agro-climatic zone is grouped based on climatic and soil conditions which doesn’t consider GE interaction of cultivars thus, releasing the cultivars for commercial cultivation considering mega environments pattern would enhance the yield for the given target region.

Combining ability status of the inbred lines is crucial information for hybrid breeding program. Diallel or line × tester mating designs are frequently used to evaluate the combining ability. In the current study a modified diallel model was used, wherein the Griffing’s combining ability effects were further partitioned to understand the effects due to maternal and reciprocal. To do this, eight parental lines of maize were crossed in full diallel method and the generated hybrids along with parents were phenotyped. The field data on the quantitative traits was analyzed using both Griffing’s and the modified model to determine how well the parents’ and the F₁ hybrids combined. For each of the traits, a sizable reciprocal and maternal variance was observed. The number of kernel rows per cob variable had a ratio of additive variance to dominance variance greater than one. All other traits including grain yield had a ratio close to zero, suggesting that non-additive gene action was primarily responsible for the genetic control of most of the traits. The narrow sense heritability was low to moderate for majority of the variables, except for number of kernel rows per cob. With the help of the improved model, it was possible to choose superior parents and cross-parent pairings with accuracy. Based on the modified general combining ability effects and maternal effects, the parental line P5 was recognized as a potential female parent and P7 as a good male parent for grain yield and yield-attributing characteristics. The cross combination of P8×P1 had the highest specific combining ability effect on grain yield. P5×P6 cross had the highest reciprocal effect. The correlation analysis implies that the Griffing’s general combining ability effects and specific combining ability effects were found to be less efficient in predicting F₁ performance as compared to the modified model.

The success of developing prominent hybrids directly depends on the selection of parents with good combining ability which can transfer desirable genes with additive effects to their progeny. The data of 42 hybrids generated using 7 × 7 full diallel design; their seven parents along with three check hybrids were subjected to combining ability analysis from the experiment that was carried out during rainy season 2019. The analysis of variance showed significant general combining ability, and specific combining ability mean sum of squares for all the thirteen characters studied. It is obvious from the results that three lines (SC Sel 2, SC Sel 1 and SC Sel 3) showed high overall general combining ability status, suggesting these lines as good general combiners across traits. Eighteen hybrids had high overall specific combining ability status, while nearly 52% (22 hybrids), 57% (24 hybrids) and 47% (20 hybrids) of crosses showed high overall mid-parent, better-parent and standard heterosis. The unique superiority of crosses involving high overall general combiner parent in the crosses highlighted the importance of using such parents to realize high heterotic crosses. A non-linear relationship between high overall specific combining ability status and heterotic status of hybrids was noticed. The probability of obtaining a cross with high standard heterosis was more with employing parents with high general combining ability status.

Development of high-yielding maize (Zea mays L.) hybrids, along with being well-adapted to many environments, is the most important goal of the National Maize Research Program in India. genotype × environment interaction (GEI) continues to be a major challenging issue to plant breeders and production agronomists. The present research investigates the (GEI), specifically examining hybrid stability and yield performance across distinct environmental conditions. A total of 62 maize hybrids were evaluated using both parametric and non-parametric methodologies across the four environments (Coimbatore, Dharwad, Hyderabad, Karimnagar) during Kharif 2021. Combined analysis of variance (ANOVA) and the Additive Main Effects and Multiplicative Interaction (AMMI) model are widely employed in multi-environment trials (MET) to evaluate genotype performance and stability. The AMMI model integrates ANOVA for assessing additive main effects with principal component analysis (PCA) to explore GEI, offering a comprehensive understanding of hybrid responses across environments. Moreover, PCA and correlation analysis were utilized to elucidate the relationships between parametric and non-parametric metrics, facilitating a comprehensive understanding of hybrid performance dynamics. The findings underscored the necessity of simultaneously considering yield and stability to harness GEI effects, thereby refining the maize cultivar selection process. The stability parameters, such as S(6), NP(2), NP(3), NP(4), KR, and CVi, were identified as effective statistics for screening desirable hybrids as they had a significant positive correlation with mean yield. Furthermore, according to the static and dynamic concepts of stability, the results revealed that stability statistics clustered into five groups. The overall stability analysis following different stability methods concluded that G51, G26, G30, G31, G12, G2, G27, G20, G47, and G56, identified as high yielding and stable across the four tested environmental conditions. Through the integration of yield and stability considerations and the utilization of analytical tools like PCA, consisting of both parametric and non-parametric statistics and cluster analysis, this study contributes to identifying resilient maize cultivars capable of confronting the challenges posed by climate change.

Maize is a widely grown cereal crop in India and ranks third to wheat and rice in production (https://iimr.icar.gov.in). During a field survey in Kharif season in 2018, foliar chlorosis at the base...

Maize is an important cereal crop of the world and in India, it is grown in the rainy and post-rainy seasons. In the rainy season, among other stresses affecting the maize productivity, drought is significant under a changed climatic scenario. Although maize is sensitive to drought at all growth stages, drought at the seedling stage results in a poor crop stand and establishment, significantly impacting productivity. Identifying moisture-stress tolerant maize inbred lines for seedling stage drought situations and using those in developing drought-tolerant hybrids play a pivotal role in increasing maize yield. In this study, a set of hybrids derived from tolerant and susceptible inbreds was studied for their response under in vitro seedling drought induced by polyethylene glycol, employing the slanting plate technique. Substantial variability among different polyethylene glycol levels (0, 10 and 20 %), maize hybrids and interaction between polyethylene glycol levels and maize hybrids was observed for germination and seedling traits, indicating differential response of the maize hybrids. Higher genetic advance with higher heritability was observed for root and shoot length, indicating the preponderance of additive gene action governing these traits. It was interesting to note that the germination ability of seeds was significantly reduced in all hybrids at 20 % polyethylene glycol, following poor seedling vigour that was reflected in diminished expression of seedling traits. The hybrids, GPM 114 × CML 451 and GPM 114 × CAL 1426-2, involving seedling drought-tolerant parents, showed lesser reduction for root length, suggesting these drought-tolerant lines can be used as donors for the development of seedling drought-tolerant hybrids suitable for cultivation in rainfed eco-systems. It is evident from the present study that screening maize genotypes at 20 % polyethylene glycol would help in identifying reliable genotypes for seedling drought tolerance.