ABSTRACT

A research work was carried out at the Agronomy Field Laboratory, Department of Agronomy, Bangladesh Agricultural University, Mymensingh, durin April to September 2008 to study the effect of variety and spacing on the growth and yield of transplant Aus rice. The experiment consisted of three rice varieties viz. BR3, BR14 and BR26 and four spacings viz. 25 cm ´ 15 cm, 20 cm ´ 20 cm, 20 cm ´ 15 cm and 20 cm ´   10 cm. The experiment was laid out in a split-plot design with three replications assigning spacings in the main plots and varieties in the sub-plots. Plant height was significantly influenced by variety and spacing during the vegetative growth phase. BR26 produced the tallest plant. The number of tillers hill-1 was the highest in BR14 and was the lowest in BR26 variety. The plant height was the highest with 20 cm ´ 20 cm spacing. BR26 with 20 cm ´ 20 cm spacing produced the tallest plant. BR14 with 25 cm ´ 15 cm spacing produced maximum number of tillers hill-1 while BR26 produced minimum number of tillers hill-1. At maturity most of the parameters significantly influenced by variety and spacing. Spacing of 20 cm ´ 10 cm produced the highest grain yield (4.23 tha-1), biological yield (9.56 tha-1) and harvest index (44.11%).The tallest plant was obtained in BR26 but the highest grain yield and biological yield were obtained in BR14 with the spacing of 20 cm ´ 10 cm. Results depicted that BR14 with the spacing of 20 cm ´ 10 cm appeared as the promising practice to maximize the yield of transplant Aus rice.

Key words: Variety, spacing, Aus rice.

Introduction

There are three distinct growing seasons of rice namely, Aus, Aman and Boro in Bangladesh and the production of rice in Aus, Aman and Boro seasons are 150.04, 981.96 and 1383.70 million ton, respectively (BBS, 2006). Aus rice is cultivated on 8.9% of the total cropped area of Bangladesh (BBS, 2006). So among these three seasons, rice production in Aus season is the least and efforts should be made to increase the production of Aus rice. The horizontal expansion of rice area in Bangladesh is not possible due to heavy population pressure. So the only avenue left is to increase the production of rice through vertical expansion. Optimum planting densities as well as improved varieties are two of the most effective means to increase the yield of transplant Aus rice. Spacing has important role on growth, yield and yield components of transplant Aus rice. Optimum plant spacing ensures the plants to grow properly with their aerial and underground parts utilizing more solar radiation and nutrients (Miah et al., 1990).Variety itself is the genetical factor which contributes a lot for producing yield and yield components. Yield is the product of some components, such as number of effective tillers hill-1, number of grains panicle-1 and weight of individual grain. These components are directly related to the variety and the neighboring environments on which it grows. Bangladesh Rice Research Institute (BRRI) has released 50 modern varieties (MV) of rice suitable for cultivation in one or more of the three rice growing seasons of Bangladesh. Each variety has certain tiller producing capacity, adequate number of effective tillers per unit area exert a role in producing panicle number and the spikelets number. Panicle number per unit area and the fertile spikelets per panicle are the most important yield components in rice. Optimum number of tillers per unit area is a prerequisite for obtaining maximum yield from a rice variety and rice yield increases with increased number of panicles per unit area (BRRI, 1992). The growth and yield of these varieties are directly related to plant spacing. Higher yield could be achieved from these varieties if they are properly spaced and managed. Optimum spacing varies not only with genotype having different growth habit but also with season, soil and climate (Have, 1992). Experiments on the spacing of transplant rice are going on here in Bangladesh and abroad to

PDF DOWNLOAD