Intercropping of dry direct seeded boro rice with leafy vegetable for better weed suppression and higher profitability

High water requirement of flood irrigated boro rice is of great concern because water is becoming scarce and expensive day by day. Dry direct seeded boro rice, grown in unpuddled and unsaturated/aerobic soil condition, requires only 50-60% water as compared to traditional flooded transplanted rice, and therefore it could be adopted as a water saving rice cultivation system in boro season of Bangladesh. Moreover, it offers a unique opportunity to grow winter leafy vegetables as intercrop. But high weed infestation is one of the major constraints in dry direct seeded boro rice. Therefore, an experiment was conducted at the Agronomy Field Laboratory, Bangladesh Agricultural University, during the period from February to June 2017 to study the feasibility of growing different leafy vegetables as intercrop in dry direct seeded boro rice for higher profitability and better weed suppression following a randomized complete block design with three replications. Four leafy vegetables viz., Jute, Gima kalmi, Indian spinach and Red amaranth were intercropped with dry direct seeded boro rice (cv. BRRI dhan28) following three different rice planting patterns such as 50 cm spaced 2 row rice strip, 75 cm spaced 4 row rice strip and 100 cm spaced 5 row rice strip; sole rice was also maintained as control. The highest weed density and dry matter were found in Indian spinach intercropping with 50 cm spaced 2 row rice strip which was statistically identical with sole rice and some other intercropping systems. Performance of Red amaranth as intercrop was the best in terms of weed suppression followed by Jute. Rice yield was the highest (3.8 t ha-1) in sole cropping, and intercropping resulted in significant yield reduction. Although intercropping diminished rice yield, but increased net return and benefit cost ratio (BCR) as compared to rice sole cropping (net return 49910 Tk ha-1 and BCR 1.58). Among the vegetables, Gima kalmi performed the best followed by Red amaranth in terms of yield. Red amaranth intercropping following 50 cm spaced 2 row rice strip resulted in highest weed suppression (32% less weed biomass compared to sole rice) while Gima kalmi intercropping following 50 cm spaced 2 row rice strip showed the highest net return (220340 Tk ha-1) and BCR (3.30).