This study was undertaken to estimate the general and specific combining ability of different female and male lines in F₁ combinations for grain yield and some important traits and estimate heterosis as a criterion for developing superior hybrids. The twenty five hybrids and their parents were evaluated at eight environments; two planting dates at two locations in 2007 and 2008 seasons. The obtained data showed that highly significant differences among parents, F₁ crosses and parents versus crosses over the two years and over all environments for traits. An evaluation of general combining ability variance components as estimated from male and/or female overall environments were larger than those of specific combining ability for days to 50% blooming, plant height and 1000-grain weight. However, opposite results were obtained for grain yield Mg ha^-1. The estimates of general combining ability and specific combining ability variance components varied greatly from location to location and from early to late planting for days to 50% blooming, plant height and 1000-grain weight. Some parents having significant negative general combining ability for days to heading and significant positive for plant height, 1000-grain weight and grain yield were considered as good combiners. Significant positive heterosis in grain yield heterosis was found for more than half of the hybrids studied. Several cross combinations showed significant positive 1000-grain weight heterosis, significant negative days to heading heterosis and good performance. Since selection of grain sorghum hybrids in this study should be based on high grain yield, early maturing, taller plants and heavier grain weight. Information on general and specific combining ability and heterosis for those four traits could contribute to more efficient breeding program.

heterosis --- Environment --- grain sorghum --- Sorghum bicolor --- hybrids

In order to obtain better knowledge about the physiological mechanism of endurance shade in different soybean cultivars, two soybean cultivars soybean with different levels of shade endurance was plant under two different light condition and the characteristics of expansins in soybean internodes and their responses to shade stress were studied. Expansin proteins were extracted from the cell walls of soybean internodes by the methods of CaCl₂ and Hepes. The activities of expansins were measured with an extensometer. The expansins extracted with CaCl₂ had higher activity than Hepes. The results demonstrated for the first time the presence of expansins in soybean internodes, it could induce extension of cell walls in soybean and in cucumber hypocotyls. The expansins activities of endogenous and reconstituted cell wall extension depended on acidic pH. The changes in activity of expansins in different soybean cultivars in response to shade stress suggest that expansins may play a significant role in the endurance of relay cropping soybean to shade stress.

cell wall --- relay cropping --- expansins --- shade stress --- Soybean

Micronutrient malnutrition, resulting from dietary deficiency of important minerals such as zinc (Zn) and iron (Fe), is a widespread food-related health problem. In a recent initiative of CGIAR’s HarvestPlus challenge program is embarked upon to address this issue through the development of biofortified cultivars with elevated levels of these micronutrients in common wheat (Triticum aestivum L.). Genetic enhancement mainly depends on existence of genetic variability available in the gene pool. Hence, the magnitude of variability for grain Zn and Fe concentrations were studied in 600 wheat core-collection accessions of diverse origin. Grain Zn concentrations among the accessions ranged from 16.85 to 60.77 mg kg^-1 and Fe concentrations ranged from 26.26 to 68.78 mg kg^-1. The highest levels of Zn concentrations were observed in a Chinese spring bread wheat accessions HONG DUAN MANG and highest Fe concentration was observed in a accession originated from Spain ‘ANDALUCIA 344‘. Top ranking accessions with high Zn and Fe concentrations are being evaluated for multi-locational testing to study the expression of these micronutrients in target countries, also these accessions are being used as potential donor for further germplasm improvement at International Maize and Wheat Improvement center (CIMMYT), Mexico. There was a highly significant and positive correlation between Zn and Fe concentrations (r = 0.81; p<0.01), indicating simultaneous improvement of both of the micronutrients would be effective and high Fe and Zn sources identified in this study provide a valuable genetic resource for breeding cultivars with high Zn and Fe concentrations.

genetic variation --- core-collection --- durum wheat --- Bread wheat --- micronutrients