Agronomic Performances of Rice Varieties at Different Transplanting Ages

Abstract

A field experiment was carried out during the period from November 2012 to May 2013 in Agroecological Zone 20 (Eastern Surma-Kushiyara Floodplain) in Bangladesh to observe the varietal performances of high yielding and local varieties of Boro rice. Four varieties viz. BRRI dhan28, BRRI dhan 29, Khoiaboro and Begunbichi, and transplanting of three seedling ages viz. 15, 20 and 25-day-old were included as treatments in the experiment. The experiment was laid out in a factorial randomized complete block design (RCBD) with three replications. The results revealed that BRRI dhan29 produced significantly highest grain yield (6.25 t ha-1) attributed by the higher number of effective tillers hill-1 (18.72), grains panicle-1 (121.09) and 1000-grain weight (22.38 g). BRRI dhan28 produced the second highest grain yield (5.37 t ha-1) while the local variety Begunbichi produced the lowest grain yield (2.26 t ha-1) in spite of its highest number of grains panicle-1 (163.92), because of its small sized grain (12.10 g 1000 grain-1). Total number of spikelets panicle-1, number of grains panicle-1, unfilled spikelets panicle-1, grain, straw and biological yield varied significantly but other characters like plant height, total number of tillers hill-1, number of effective tillers hill-1, number of non-effective tillers hill-1, length of panicle, 1000 grain weight and harvest index did not among different ages of seedlings. The highest grain yield of 4.49 t ha-1 was obtained from planting 25-day-old seedlings ascribed to higher number of grains panicle-1. Grain yield of 4.23 t ha-1 was obtained from planting 20-day-old seedlings which was statistically similar to that of planting 25 and 15-day-old seedlings. Interaction of variety and seedling age produced significant effect on days to 50% flowering, days to maturity, number of effective tillers hill-1, total number of spikelets panicle-1, number of grains panicle, number of unfilled spikelets panicle-1, 1000 grain weight, straw and biological yield. This indicates that all varieties require planting 25-day-old seedlings to obtain higher grain yield. Cost and return analysis showed that BRRI dhan29 gave maximum gross return, net return, and benefit cost ratio of US$ 1665.00 ha-1, US$ 699.28 ha-1 and 1.72, respectively with planting 25-day-old seedlings. In spite of lower yield of local variety Begunbichi, it gave higher net return and benefit cost ratio because of its higher selling price than BRRI dhan28 and local Khoiaboro varieties with the same 25-day-old seedlings.