EFFECT OF SOURCE-SINK MANIPULATION ON THE YIELD OF RAINFED RICE (Oryza sativa L.)

Abstract

The present study includes the experiment on source-sink manipulation and their effect on grain yield in rice of rainfed varieties. This experiment includes the performance of 16 varieties. Among these, 10 varieties were BRRI high yielding, 1 was BINA high yielding and other 5 varieties were local. This experiment was conducted in the field of Genetics Resource & Seed Division of Bangladesh Rice Research Institute, Joydebpur, Gazipur from June 2005 to October 2005 with three replications and nine treatments. The effect of treatments on the varieties of rainfed rice for grain yield and different sink characters were evaluated. Significant variation was observed for all the characters among the varieties and treatments but interaction (genotypes X treatments interactions) was not significant. Among the 16 genotypes the variety BRRI dhan32 gave the highest grain yield with lowest days to maturity and moderate leaf area in control conditions. Performance of the genotypes was different under different conditions of source sink manipulations. Among the genotypes, Daksail, BRIO and BRRI dhan40 produced higher number of spikelets per panicle but their grains sized were comparatively small. The genotypes Rajasail, Hogla, Swarnalata, BRRI dhan3l and BR23 produced large size grains but their grains were less number comparatively. The genotypes BR23, Rajasail. BRRI dhan30, BRRldhan41, Patnai23, and were the best materials for grain yield per plant. Among them the genotypes Patnai23, Rajasail and BR23 produced large sized grain and also produced comparatively high grain yield per plant in case of imposed conditions. Effect of source-sink manipulations on grain yield and different sink characters were analyzed. It was observed that the defoliation of flag leaf caused significant reduction on spikelets per panicle, 1000 grain weight and grain yield per plant by 17.34%, 10.69% and 34.82% respectively. Similarly the removal of penultimate leaf caused reduction of 10.98%, 6.45% and 22.67% for spikelets it per panicle. 1000 grain weight and grain yield per plant respectively. On the same way the defoliation of third leaf caused reduction of 7.20%, 3.59% and 15.67% for spikelets per panicle, 1000 grain weight and grain yield per plant respectively. Similarly the defoliation of flag leaf, penultimate leaf and third at a time caused reduction of 29.2%, 15.67% and 54.67% for spikelets per panicle, 1000 grain weight and grain yield per plant respectively. On the other hand, there was 37.02% and 56.31% reduction in spikelets per panicle and grain yield per plant respectively but 6.33% increase in 1000 grain weight by sink manipulation (removal of 50% spikelets). Both these facts indicated that the present materials suffered from source limitation, therefore it would be concluded that the flag leaf contributed 34.82% in the total grain production per plant. The penultimate leaf contributes 22.67% in the grain yield per plant, third leaf contributes 15.67% in the grain yield production of rainfed rice.