Abstract
Five field experiments were conducted on seedling age, spacing, fertilizer and water management aspects of system of rice intensification popularly known as SRI with a view to maximizing yield and profitability of Boro rice through integration of the system with BRRI recommended techniques at BRRI experimental farm, Gazipur during November - May, 2001-04. The integration of SRI recommended younger seedlings with BRRI recommended spacing, chemical fertilizers and water management increased 5-11% grain yield and 6-20% gross margin of Boro rice over BRRI recommended technique. Yield advantage with integrated technique was 27 and 71% higher over SRI technique with and without chemical fertilizer, respectively. The integrated technique also increased bearing and nonbearing tillers m2, total dry matter, leaf area index, crop growth rate, gross return and benefit-cost ratio of both SRI and BRRI recommended techniques. With younger seedlings there was risk of high seedling mortality due to cold injury if transplanted in January. The yield of integrated technique was lower than BRRI technique when the crop suffered from cold injury. Ideal SRI technique did not have any yield advantage over BRRI recommendations rather SRI water management encouraged weed growth and subsequently increased weeding cost. Weeding cost in SRI technique was increased by 25-59% over BRRI technique but total variable cost was increased by only 1-3%. The range of total variable cost (TVC) was Tk. 27,060-27,493 and Tk. 26,587-26,920 under SRI and BRRI techniques, respectively. Water requirement was reduced by 27-35% in SRI technique over BRRI technique though frequency of irrigation was increased by 133-138%. To maximize yield and profitability, integration of SRI recommended younger seedlings with BRRI recommended spacing, chemical fertilizers and water management may be advocated for early transplanted Boro rice.