Asian Research Thesis Index

Abstract

Drought is a solemn environmental factor that causes great loss of yield in maize crop. Maize is highly sensitive to drought. There is need to develop drought tolerance maize genotypes to fulfill demand of feed for livestock and food for human. For this propose prescribed study was conducted in the glasshouse (Experiment 1) and research area (Experiment 2) of Department of Plant Breeding and Genetics, University of Agriculture Faisalabad, Pakistan. Forty maize inbred lines were collected from different research organizations such as Department of Plant Breeding and Genetics, University of Agriculture Faisalabad, Maize and Millet Research Institute, Sahiwal and Fodder Research Institute, Sarghodha, Pakistan during crop season of 2009. The inbred lines were screened for drought tolerance under glasshouse conditions. Heritability, genetic advance and genotypic correlations were found higher for root length, shoot length, fresh root weight, fresh shoot weight, dry root weight and dry shoot weight under normal and drought conditions. On the basis of fresh root and shoot length two inbred lines P1 (WFTMS) and P2 (Q66) were selected as drought resistant and sensitive parents respectively. F1, F2, BC1 and BC2 were developed and evaluation of basic six generations was performed under normal and drought conditions. It was found that high correlation coefficients were found among plant height, cell membrane thermo-stability, leaf area, cob length, cob girth, rows per ear, grains per ear row, biomass per plant, 100-grian weight and grain yield per plant under normal condition and drought conditions. Narrow sense heritability of generations was found higher for leaf water potential, cell membrane thermo-stability, stomata size, excised leaf water loss, plant height, leaf area, cob length, cob girth, grain rows per cob, biomass per plant, grain yield per plant under normal condition while under drought condition for cell membrane thermo-stability, stomata conductance, leaf water potential, leaf area, cob length, cob girth, biomass per plant, 100-grain weight, grain yield per plant. Additive effects were found higher for biomass per plant, leaf area and leaf water potential under normal condition while under drought condition for cob girth. Higher additive effects indicated that selection of these traits may be helpful for further breeding program. Dominance effects were reported for cell membrane thermo-stability, leaf water potential, stomata frequency, plant height, leaf area and grain yield per plant under normal condition while plant height and grain yield per plant under drought condition. Selection on the basis of dominant effects indicated that increase may be achieved for these traits to improve grain yield in maize. Positive additive × additive interaction were found higher for cell membrane thermo-stability, stomata frequency, leaf water potential, excised leaf water loss, cob girth, plant height, leaf area and 100-grain weight under normal condition. While; stomata frequency, stomata conductance, cell membrane thermo-stability, excised leaf water loss, plant height, grain per ear row and grain yield per plant under drought condition. Positive i indicated that increase in these traits may be fixed for the improvement of yield in maize under normal and drought conditions. Additive × dominance interaction was found higher for grain per ear row under drought condition which indicated that selection may be delayed till further generations. Positive dominance × dominance interaction was found greater for biomass per plant and grain yield per plant under normal condition, and grain per ear row under drought condition but which were due to negative dominance genetic effects and may not be helpful for the improvement grain yield in maize. On the basis of heritability, genetic advance, correlation and genetic effects concluded that fresh shoot weight, dry shoot weight, root length, shoot length and emergence percentage at seedling stage, stomata frequency, stomata size, cell membrane thermo- stability, leaf temperature, excised leaf water loss, plant height, leaf area, biomass per plant, cob girth, 100-grain weight, grain yield per plant at maturity stage may be helpful for the development of higher grain yield maize genotypes under drought conditions.

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