| Results and Discussion Temperature data : Maximum temperature was found some what lower than normal during the month of September (31.5C), November (29.1C), January (26.4C) and Febraury (28.1C) whereas found close to normal during the month of October (34.5C) and comparatively higher in December (28.4C) and March (34.2C). Table 1 shows that even normal temperatures of these months are not suitable for the normal development of wheat plant, though this Zone is traditionally wheat growing areas. Rainfed wheat is generally planted after 15th October, which flowers in mid January and matures by mid March. The early growth and ripening both occurs under comparatively higher temperature conditions. Temperature above 25C decrease relative growth rate of wheat through their influence on leaf growth and net assimilation rate (FRINED et al. 1965). Increasing the temperature from 10-30C increased the rate of elongation of developing spikes resulting smaller Spikes (FRIEND 1966). According to ASANA (1972), higher terperature after germination hasten differentiation and reduced tillering (as quoted by SISODIA et al. 1978). ASANA (1976) studying the effect of temperature under controlled conditions (range 25C to 31C) On grain development in 2 Australian cultivars 'Ridley' and 'Diadem' and 3 Indian cultivars 'NP 824' 'NP830' and 'Pbc 281', observed that 6C rise in day terperature decreased the mean grain weight by 16%. In this study, genotypes were exposed to approximately 9C higher temperature than the normal requirements (25C) of wheat plant during early growth stages and found relatively tolerant to high temperature. Correlation : Highly significant difference for all the traits under study indicated wide gentic diversity among the genotypes (Table 2). In general, results revealed comparatively higher magnitude of genetic correlations than Phenotypic correlations (Table 3) indicating that selection for genetically associated characters could give better response in yield than would be expected on the basis of Phenotypic association (ROBINSON et al. 1951). At the genotypic level grain yield per plant had strong and highly significant positive correlations with grain weight per ear ( .882**). Plant height ( .740**) and ear length ( .614**). Grain weight per ear seemed to be most important character, due to its high correlation coefficients. Suggesting that an increase in grain weight per ear may considerably increase the plant yield under stress conditions (SIKKA & MAINI, 1962 ; SRIVASTAVA et al. 1980). |
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