Muhammad Ahsan

Phenotypic stability under stress environment facilitate the fitness of genotype and opens new horizons to explore the cryptic genetic variation. Variation in tolerance to drought stress, a major grain yield constraint to global maize production, was identified, at the phenotypic and genotypic level. Here we found a prominent hybrid H9 that showed fitness over four growing seasons for grain yield under water stress conditions. Genotypic and phenotypic correlation of yield attributing traits over four seasons demonstrated that cobs per plant, 100 seed weight, number of grains rows per cob, total dry matter, cob diameter had positive association (r2 = 0.3-0.9) to grain yield. The perturbation was found for chlorophyll content as it showed moderate to strong association (P < 0.01) over four seasons, might be due to environment or genotype dependent. Highest heritability (95%) and genetic advance (79%) for grain yield was found in H9 over four consecutive crop growing seasons. Combined analysis over four seasons showed that studied variables together explained 85 % of total variation in dependent structure (grain yield) obtained by principle component analysis. This significant finding is the best example of phenotypic stability of grain yield in H9 and made it best fitted for grain yield under drought stress scenario. Detailed genetic analysis of H9 will help us to identify significant loci and alleles that made H9 the best fitted and it could serve as a potential source to generate novel transgressive levels of tolerance for drought stress in arid/semiarid regions.

Background:  Maize is one of most important cereal crop in world after wheat and rice. It is grown in Pakistan as a major cash crop cultivation in the area of 1083 thousand hectares producing 3990 thousand tones. Maize is dual propose crop it is used as feed for livestock and food for human. It is also used as a raw material in textile, food and medicine industries. The present study was conducted to evaluate parents and F 1  hybrids of maize for seedling traits including heritability, heterosis and heterobelteiosis. Methodology:  The genetic material was comprises of twelve parents and including their 36 F 1  hybrids. The parents and F 1  hybrids were sown in the iron treys filled with sand in three replications following completely randomized design. The data was recorded for fresh root length, fresh shoot length, fresh root-to-shoot length ratio, fresh root weight, fresh shoot weight and fresh root-to-shoot weight ratio. The data was subjected for analysis genotypic and phenotypic coefficients of variance. The genetic advance was calculated by using Falconer (1989) formula. Results:  The average batter performance was given by B-336, EV-347, EV-1097Q and B-327. The F 1  hybrids, EV-1097Q × EV-347, EV-1097Q × EV-340, Raka-poshi × EV-347, B-327 × B-316 and Sh-139 × EV-347 showed higher values of heterosis and heterobeltiosis for respected studied traits of maize seedlings. Conclusion:  In this study, it is concluded that the F 1  hybrids, EV-1097Q x EV-347, EV-1097Q x EV-340, Raka-poshi x EV-347, B-327 x B-316 and Sh-139 x EV-347 may be used as higher yield maize hybrids and parents EV-347, EV-1097Q, B-327 and B-316 may be used to develop higher yield maize hybrids following heterosis breeding scheme.

Background : Maize is an important cereal crop, grown throughout the globe for human food and livestock feed, but biotic and abiotic factors had shown adverse effects on biomass and grain yield. Changing climatic conditions have imposed drought (water scarcity) as a major problem to combat with yield losses and biomass in maize and other cereals. Methods: The prescribed study was conducted to evaluate F 1 hybrids at seedling subject to 45% moisture level. The data was recorded and subjected to multivariate analysis to find the significant variation attributed by various traits under stress conditions for efficient root/shoot development. Results: Significant differences were found in F 1 hybrids for all studied traits. Higher heritability was found for root length, shoot length and fresh shoot weight, while fresh shoot weight, dry shoot weight and dry root weight showed higher genetic advance. Significant correlation was found for dry root weight to fresh shoot length and fresh root length, fresh root weight to fresh root/shoot weight ratio and fresh shoot weight. The hybrids Sh-139×B-316, Raka-poshi×B-316, B-327×B-316, Sh-139×EV-340, EV-1097Q×EV-347, EV-1097Q×EV-340, EV-1097Q×Pop/209 and B-327×EV-340 showed higher and positive heterosis and heterobeltiosis for most of the studied traits. To assess the overall variation on dependent structure, we used multivariate analysis, an important tool in breeding program, for efficient selection. Conclusions : EV-1097Q×Pop/209 and Sh-139×EV-340 showed significant results for root and shoot development under various water stress regimes at seedling stage, thus further studies should be carried out to find out the known and un-known loci regarding root and shoot development traits in high yielding maize cultivars under arid/semi-arid regions.

Background:  Zea mays  L. is one of the most imperative cereal crop in world after wheat and rice. It is a used as food for human and feed for livestock. To meet the ever increasing demand, maize production can be increased by application of improved agronomic techniques to get varieties with higher qualitative and quantitative traits and resilience to abiotic stresses. Methods:  The genetic material was comprised of 8 parents and 12 F1 hybrids. The genotypes were sown in the iron treys filled with sand in three replications following completely randomized design. The data was recorded for fresh root length (FRL), fresh shoot length (FSL), fresh root-to-shoot length ratio (FRSLR), fresh root weight (FRW), fresh shoot weight (FSW), total fresh weight (TFW), fresh root-to-shoot weight ratio (FRSWR), dry root weight (DRW), dry shoot weight (DSW) and total dry weight (TDW), dry root-to-shoot weight ratio (DRSWR), chlorophyll contents (Ch.C), leaf temperature (LT), transpiration rate (E), photosynthetic rate (A), stomata conductance (gs), water use efficiency (WUS) and sub-stomata CO2 concentration (Ci). GCA (general combining ability) and SCA (specific combining ability) were calculated by using Kepmthorn, (1957) technique. Results:  Higher GCA of B-336 variety was recorded for FRL, FRW, FSW, TFW, A and Ci. Higher SCA of EV-1097Q × Pop/209, Sh-139 × Pop/209, EV-1097Q × B-316 and Sh-139 × B-316 varieties was recorded for FRL, FSL, FRW, FSW, TFW, A, Ci, WUE, LT, E and gs. Conclusion:  Higher heritability, genetic advance, GCA and SCA had decisive role in selection of drought tolerant maize varieties. F1 hybrids EV-1097Q × Pop/209, Sh-139 × Pop/209, EV-1097Q × B-316 and Sh-139 × B-316 showed higher SCA for all traits that persuaded that these hybrids may be used for higher grain and fodder yield under drought conditions.