Studies on Genotypes. Age and Productivity in Rice

Abstract

Eight improved genotypes of rice of early, short and medium duration were assos- sail for the tolerance of delayed planting of the seedlings in two different seasons. Planting aged seedlings resulted in increase in field duration and reduction in grain yielle. The field duration was increased in all the varieties by 5 to 10 days for avery 10 days of delayed planting. The decrease in yield ranged from 2 to 50 per cent in short duration and from 4 to 41 per cent in medium duration varieties as compared to the performance of 20 days old seedlings. An evaluation of the yield components brought out decrease in the menn expression of yield components. There was a marked difference between the genotypes as a whole as also bet ween genotypes of different duration groups. Among the genotypes studied. ADT 31 and IR 20 exhibited considerably less differences between seedlings of different ages in their performance and showed tolerance for delayed plantings. The studies indicate possibilties of screening and developing genotypes that could be tolerant for delayed planting especially in certain agroclimatic regions where constraints prevail over planting in proper age of nursery.