Stem reserves utilization during grain filling in modern and old rice cultivars of different maturity groups

Abstract

Abstract : Dry matter accumulation in stem and its utilization towards grain of fifteen modern and eighty four old cultivars of rice were studied. The cultivars were collected from different ecological regions of Bangladesh and grown in the experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University during aman season of 1994. Rice cultivars were grouped according to their maturity period as very early, early, medium, late and very late. Dry matter accumulation were more in old cultivars but translocation to grain was higher in modern cultivars of rice. The amount of stem reserves translocated towards grain was 43.3% in modern and 24.3% in old cultivars of rice. Considering maturity group, late maturing cultivars superseded the early maturing cultuvars in dry matter accumulation but it was reversed in contribution to grain. The extent of dry matter translocation varied widely across the cultivars groups. Utilization of stem reserves was 43.5% in early maturity while the corresponding value for late maturity cultivars was only 22.6%. However, very late maturing cultivars contributed higher stem reserves than the medium maturity group of rice cultivars.