All India Coordinated Rice Improvement Project, Rajendranagar, Hyderabad-500030
Grain size showed negatively linear relationship with number in early duration group of varieties. The decrease in grain number with increased size was mainly due to the decreased number of grains per panicle. The grain number recorded was of the order of 25 x 102 which was lower in comparison to the grain number recorded in medium and late duration group of varieties. Grain size was found to be not related to grain yield. Apparently increased grain number at any given size would result in higher yields. Suitable blending of grain size and number would lead to further increases in yield potential. At a given grain size, grain yields differed suggesting greater scope for manipulations. Based on the grain filling pattern in terms of growth rate and peak filling periods, the varieties were grouped wish peaks around 10, 15, 20 and 25 days after flowering. The grain size was not found to be related to grain filling periods and growth rate of grains. Although fast and slow grain filling periods are not related to higher yields, but considering the climatic conditions like relatively high temperatures of tropics and sub tropics, fast falling is advantageous.
