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Genotypic and phenotypic correlation among sixteen component characters was studied in 52 genotypes of Rice. Association analysis of parents revealed that Days to 50% flowering, plant height, seedling maturity after transplanting, number of productive tillers, Panicle excertion had high significant positive correlation with cold tolerance. Number of seeds/head, 100 seed weight, head diameter and per cent seed filling also had significant positive inter-correlation among themselves. Seedling growth (cm), panicle length, Days to 50% flowering, early seedling vigor and seed vigor influenced indirectly. Hence, this trait should be given priority in rice improvement programme for cold tolerance.
Rice (Oryza sativa L.) is the world’s most staple food for about 2.5 billion people and which may escalate to 4.6 billion by the year 2050 . Because of change in climate, the rabi season has low temperature vary from 8oC to 16oC starting from December to first fortnight of February . The optimum day temperature before heading is 31o – 32oC and optimum night temperature is 21o – 22oC and the period for 15 days after heading varies from 8o to 16oC. Rice might suffer from low temperature at the seedling stage of the crop . Even low temperature at the crop establishment and tiller development stage (vegetative phase) of the crop might affect the growth and development of the crop. Conventional high yielding varieties have little tolerance to low temperature. The major constraint is lack of suitable varieties for this ecosystem. Therefore, the technique of path coefficient analysis is utilized to have an idea of direct and indirect contribution of a trait towards the end product. The present investigation was undertaken to gather some useful information on genetic variability, character association and path coefficient analysis in a set of 52 rice genotypes.
Arid Tropics (ICRISAT) Campus Patancheru, Hyderabad, India. Situated at 17.53oN latitude, 78.27oE longitude and altitude of 545m above mean sea level with 52 genotypes of rice from different boro areas. Each entry was represented by single row of 4.5 m length with a spacing of 20 cm between rows and 15 cm between plants in a Randomized Block Design with three replications. Thirty days old seedlings were transplanted with a spacing of 20 cm and 15 cm between rows and plants, respectively. Five representative plants for each genotype in each replication were randomly selected to record 15 observations.
Correlation studies conclude Days to 50% flowering, plant height, seedling maturity after transplanting, number of productive tillers, seed vigor showed positive and significant association among themselves, indicating that simultaneous selection for these characters would result in improvement of cold tolerance of rice crop. Path analysis conclude that seedling growth (cm) , panicle length, Days to 50% flowering , Early seedling vigor and seed vigor were the most important characters which could be used as selection criteria for effective improvement of cold tolerance. Therefore, due weightage should be given on these characters during selection for pedigree breeding work.
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