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Current experiment is conducted to study correlation and path analysis among morphological traits and their contribution towards yield under normal and drought stress using twenty diverse rice genotypes at

Combining ability analysis was performed in order to identify high-yielding genotypes and hybrids. Six lines were crossed with three testers using a line × tester mating design. General combining ability (GCA) of parents, specific combining ability (SCA) of hybrids and gene action for several yield components and fibre were studied in the experiment. Additive gene action was observed in most traits except bolls/plant, sympodia/plant, monopodia/plant, total nodes, seed index, lint/seed, staple strength and seed cotton yield/plant which were influenced by non-additive gene action. GCA revealed that Giza-7 was a good general combiner for staple length, staple strength, seed index, boll weight, bolls/plant and monopodia/plant and BH-167 was good for ginning outturn (GOT) and sympodia/plant. Results of SCA values for hybrids indicated, that the cross Giza-7 × MNH-886 was a superior specific combiner for staple length, monopodia/plant, staple strength and seed cotton yield/plant; CIM-554 × CIM-557 for boll weight, sympodia/plant and lint weight/boll; BH-167 × MNH-886 for GOT and bolls/plant. Selection of such hybrids and good general combiners could be further exploited for yield improvement.

Rice (Oryza sativa) falls among the staple food crops in different parts of the globe. In current scenario of climate change, drought stress leads to significant decrease in crop production. It has negative effect on rice growth and development by affecting cellular, physiological and molecular processes. Photo-respiration increases under drought stress leads to overproduction of reactive oxygen species (ROS) in different organelles of the cell like chloroplasts, mitochondria and peroxisomes etc., which induce severe oxidative stress in rice. Over production of ROS can cause damage to proteins, lipids and DNA leading to lipid peroxidation, proteins oxidation, mutation, DNA damage that can lead to cell death. Under drought stress, ROS turn over in various organelles overload antioxidant quenching mechanism leading to oxidative damage. Oxidative stress can be overcome by the scavenging system, which consists of enzymatic and non-enzymatic antioxidants. Moreover, ROS also acts as signaling molecule and triggers defense mechanism through specific signal transduction network under stress. Under stress condition, activation of molecular cascades is initiated through the perception of stress that leads to the activation of signal transduction pathway including expression of transcription factors and stress related genes. Understanding of this regulatory mechanism of plant development and growth in drought-ROS stress can be promising in the development of improved transgenic rice under this stress. This review will provide an overview of ROS synthesis and signaling pathway under drought condition in rice.

ABSTRACT. Interspecific and intraspecific hybrids show varying degrees of heterosis for yield and yield components. Yield-component traits have complex genetic relationships with each other. To determine the relationship of yield-component traits and fiber traits with seed cotton yield, six lines (Bt. CIM-599, CIM-573, MNH-786, CIM-554, BH-167, and GIZA-7) and three test lines (MNH-886, V4, and CIM-557) were crossed in a line x tester mating design. Heterosis was observed for seed cotton yield, fiber traits, and for other yield-component traits. Heterosis in interspecific hybrids for seed cotton yield was more prominent than in intraspecific hybrids. The interspecific hybrid Giza-7 x MNH-886 had the highest heterosis (114.77), while among intraspecific hybrids, CIM-554 x CIM-557 had the highest heterosis (61.29) for seed cotton yield. A major trait contributing to seed cotton yield was bolls/plant followed by boll weight. Correlation studies revealed that bolls/plant, boll weight, lint weight/boll, lint index, seed index, lint/seed, staple length, and staple strength were significantly and positively associated with seed cotton yield. Selection based on boll weight, boll number, lint weight/boll, and lint index will be helpful for improving cotton seed yield.