Genetic Variations of Leaf Trait in Maize (Zea mays L.) under Drought Stress in Different Growth Stages

Maize is the third most important food crop worldwide, and it is more sensitive to drought. Two field experiments were conducted under drought in different growth stages at two locations, the Demonstration Farm, Faculty of Agriculture, University of Khartoum, at Shambat, and the Gezira Research Station Farm, at Medani, in season (2003/2004). To estimate the pattern of inheritance, determine the relative magnitude of genetic variation effects for a number of leaves/plant and leaf area index in fifteen maize genotypes. A split-plot design, layout within randomized complete block design with three replications was used for the experiment. Significant differences among genotypes were detected in all traits, except, leaf area index (30 and 60 days) and number of leaves/plant (45 days). High genotypic coefficient of variation, genetic advance and heritability were exhibited by a number of leaves/plant for 60 days. Grain yield was significantly and positively associated at the phenotypic level with the leaf area index and a number of leaves/plant at 60 days. Thus the characters leaf area index and number of leaves/plant to be the important traits which would be an effectual in selection for maize improvement under drought stress at different growth stages. Based on their positive association with grain  yield, the traits  leaf area index and number of leaves/plant would be the exploited for improving grain yield and facilitate further efforts in the maize improvement program in the country. Keywords: correlation; heritability; morphological traits; vegetative and reproductive phases; water stres

Genetic Variation of Flowering Trait in Maize (Zea mays L.) under Drought Stress at Vegetative and Reproductive Stages

A study was conducted under water stress in vegetative and reproductive growth stages at two locations (Shambat and Medani) in Sudan during the season (2003/2004). Genotypic and phenotypic variability, genetic advance and heritability in a broad sense were estimated in a split-plot layout within randomized complete block design with three replications. Fifteen genotypes of maize were used for the study.  Phenotypic correlation coefficient between grain yield and 25%, 50% and 95% of flowering trait anthesis and silking were evaluated. All flowering stages were found significant differences among the genotypes, except days to 95% anthesis. Significant differences among water treatments were observed for days to 25% silking at Medani. High heritability, genotypic coefficient of variation and genetic advance were exhibited by days to 25% silking. Grain yield was significantly and negatively associated with days to (50% and 95%) silking. Based on the results drought stress at vegetative and reproductive stages of maize results in a drastic reduction in grain yield, and flowering character would be the important selection, creation for maize improvement under drought stress. Keywords: Maize (Zea mays L.), Genetic variability, heritability, correlation, flowering, drought

Phenotypic Variations of Drought Tolerance Parameters in Maize (Zea mays L.) under Water Stress at Vegetative and Reproductive Stages

Two field experiments were conducted at Shambat and Medani in Sudan under water stress in vegetative and reproductive growth stages during the season (2003/2004). The objective of the study was to assess phenotypic variability and phenotypic correlation between drought tolerance parameters in maize genotypes. A split-plot layout within randomized complete block design with three replications was used for the experiment. Fifteen genotypes of maize were examined through the study. The effect due to genotypes x location was highly significant for all drought tolerance parameters studied. Highly significant and favorable correlation for Yw with SSI2, SSI3, GMP2, GMP3, STI2 and STI3, while highly significant and negative with Yd2/Yw and Yd3/Yw. Based on the result's drought stress at vegetative and reproductive stages of maize results in a drastic reduction in grain yield, and the strong positive correlation of Yw with SSI, GMP and STI, indicates that selection for high values of these parameters improves yield under stress and non-stress environments. Drought tolerance parameters can be used for improving grain yield and facilitate further efforts in maize breeding programs. Keywords: Correlation, drought, genetic variability, heritability, Maize (Zea mays L.).

INTERACTIVE EFFECTS OF HEAT STRESS AND WATER DEFICIT ON THE PERFORMANCE OF CHICKPEA (Cicer arietinum L.) GENOTYPES IN SUDAN

Climate variations pose significant challenges for chickpea production. Increases tolerance to heat stress and water deficit is an important option to increase chickpea productivity in Sudan. This study aimed to evaluate the performance, stability and correlation between different traits of nine chickpea genotypes under different conditions. The genotypes were tested at two locations; Hudeiba for three seasons (2007/08, 2009/10 and 2010/11) and Shambat during season 2008/09. To induce stresses, four treatments were used: non-stress, terminal heat stresses, water stress and combination of heat and water stresses. A split-plot design with three replications was used where the stress treatments were assigned to main plots and genotypes to subplots. The results showed that heat, water and combined stresses significantly affected all studied traits. Heat stress induced more reduction than water stress for most of the traits, however combined stress imposed the highest effect. Significant differences between genotypes for all studied traits were also found. The interactions between the genotypes and treatments were significant for most of studied traits. Some genotypes were found tolerant and stable under water deficit (Wad Hamid and Shendi), heat stress (Hwata), or combined stress (Wad Hamid) conditions. Seed yield positively and significantly correlated with number of pods/plant, number of seeds/plant, 100- seed weight and plant height and these traits could be used as selection criteria for breeding high yielding genotypes. It could be concluded that cultivars differentially responded to heat, water and combined stresses, indicating that further improvement in the tolerance of chickpea to these stresses could be achieved