Adaptive Trial on Hybrid ( F1) Rice Seed Production at the Level Barind Environmental Conditions

The hybrid rice technology to suit Bangladesh situation was basically established in 2001. The first hybrid (BRRI hybrid-1) was also released for commercial cultivation in the same year. BRRI has released the hybrid (F1) rice seeds in a modest scale through their regular research programme. For wider adoption in different agro-ecological zones (AEZs) of the country limited adaptive and on-farm trials have been conducted by BRRI for identifying its location specific adaptability and performance. Still, there is room for conducting adaptive trial on the parent line in different AEZs to determine the appropriate production technology for higher yield and minimize the cost of production. However, seed yield obtained from a male sterile line used in a hybrid seed production plot is a function of (a) yielding ability of the male sterile line, (b) proportion of male sterile line to pollen parent, and (c) out crossing rate of the male sterile line. Improvement in any of these components can help to increase hybrid rice seed yield.

This adaptive trial was carried out to achieve the following objectives:

1.      To assess the yielding ability of parent lines (by varying planting proportion of A to R lines) developed by BRRI in the Level Barind environmental condition;

2.      To develop agronomic management protocol on F1 hybrid rice seed production during Boro season for the Level Barind ecosystem;

3.      To establish a database on technical and economic aspects of hybrid rice seed production for imparting training to mass farmers and the local seed agencies.

Based on regular research, BRRI has standardized the practices for hybrid rice seed production in Bangladesh, which are packaged in manuals. Using these practices along with two different planting proportions of A to R lines viz: 2:4, 2:6 and 2:8 (the later one has been standardized by the BRRI for Bangladesh), we could launch the hybrid rice seed production at RDA demonstration farm in the Boro season, 2005. The trial was conducted through a randomized complete block design (RCBD) with three replications. Yield and yield contributing characters were analyzed through ANOVA and DMRT.

The highest yield 1.4 t ha-1 seeds were produced in the planting proportion 2:6 followed by 2:4 where yield obtained 1.09 t ha-1, these yields were higher significantly about 40% and 23% more than the yield (0.84 t ha-1) obtained in the plots where the planting proportion 2:8 were used that has been standardized by BRRI. By using BRRI standardized planting proportion of A to R lines for hybrid rice seed production, seed yields were found rather low in RDA farm in comparison to the planting proportion 2:6.  Lower yield may be attributed to significantly lower out crossing rate in planting proportion 2:8 due to location, local soil and environmental factors in spite of the best adjustment of sowing time and agronomic practices to avoid it. The costs of production per kg seeds in the planting proportion 2:6 was taka 68.00, whereas the cost of production per kg seeds reaches to taka 113.00 in the case of the planting proportion 2:8. Therefore, the results of this adaptive trial i.e., the planting proportion 2:6 was found more suitable for producing hybrid (F1) rice seeds to the local environmental settings in the Level Barind ecosystems. By using the planting proportion 2:6, local farmers in the Barind location (AEZ-25) can get higher seed yield, even 40% more than the yield obtained in planting proportion 2:8, and minimize the costs of production by 39%.