INFLUENCE OF PLANTING DATES ON THE MORPHOLOGiCAL AND YIELD ATTRIBUTES OF SOME HYBRID RICE (Oryza sativa L.) VARIETIES IN AUS SEASON

Abstract

An experiment was conducted at the field of Agricultural Botany Department, Shcr-eBangla Agricultural University (SAU). Dhaka during Mis season from March to July 2010. with a view to study the influence of planting dates on the morphological and yield attributes of hybrid rice varieties. The experiment consisted of two levels of treatments viz. A: Three varieties where two of them were hybrids and one was inbred: BRRI Hybrid dhan2, Tia and BRRI dhan48 (Inbred). B: Four transplanting dates: 16th March, 3 1 " March, 15th April and 30th April. The experiment was laid out in factorial randomized complete block design with three replications. Experimental results indicated that transplanting dates and varieties individually had significant effect on the growth and yield parameters like plant height, number of total tiller hilt', leaf area hill", total dry weight (g hillj, light interception percent, chlorophyll content at flag leaf stage, number of effective tiller hilt', panicle length, number of filled spikelet panicle", number of unfilled spikelet panicle", number of total spikelet panicle1, spikelet filling percent. grain yield (t ha'1), straw yield (t ha"), biological yield (t hi') and harvest index (%). The results revealed that 16" March transplanting gave the highest grain yield. Chlorophyll content was higher in BRRI Hybrid dhan2 followed by Tia. In contrast chlorophyll content was lower in BRRI dhan48. Among the varieties BRRI dhan48 gave the highest grain yield but both the hybrid varieties BRRI Hybrid dhan2 and Tia gave lower grain yield due to higher spikelet sterility because of more sensitiveness of hybrid rice varieties to high temperature and low sunshine hour at grain filling stage. The combined effect of transplanting dates and variety had also significant effect on yield and yield contributing characters. BRRI dhan48 transplanting on 16th March showed highest grain yield attaining good yield contributing characters.