Abstract
The present study was aimed at evaluating water requirement and yield performance of Boro rice
under dry direct seeded system and also to develop suitable agronomic management practices for
this system. Four experiments were conducted under this study during 2009-10, 2010-11 and
2011-12 Boro seasons. In Experiment 1, water requirements and yield performances of BRRI
dhan28 and BRRI dhan29 were evaluated under three cultivation systems viz. puddled
transplanting with conventional irrigation (PTR-CI), puddled transplanting with alternate wetting and
drying irrigation (PTR-AWDI) and dry direct seeding Boro rice (DDSR) in 2009-10 and 20010-11. In
Experiment 2, six seed rates viz. 30 kg ha¹ (25 cm x 15 cm with 4 seeds hill¹), 30 kg ha¹
(continuous seeding at 25 cm apart rows), 40 kg ha¹ (continuous seeding at 25 cm apart rows), 50
kg ha¹ (continuous seeding at 25 cm apart rows), 60 kg ha¹ (continuous seeding at 25 cm apart
rows), 70 kg ha¹ (continuous seeding at 25 cm apart rows) of BRRI dhan28 and BRRI dhan29
were used. Experiment 3 included three depths of seeding viz. 2, 5 and 8 cm; and seven weed
management options viz. no weeding (M₁); four hand weeding at 20, 35, 50 and 65 DAS (M2);
blade weeding plus three hand weeding at 20, 35 and 50 DAS(M3); Blade and Rake plus three
hand weeding at 20, 35 and 50 DAS(M4); three pre-emergence herbicides viz. Sirius 10 wp
(Pyrazosulfuran-ethyl) @ 125 g ha¹(Ms) Top (Pretilachlor) @ 1 L ha¹ (M6), and Panida
(pendimethalin) @ 2.5 L ha¹ (M,) at 2 and 20 DAS plus one hand weeding before application of
herbicide at 20 DAS using Boro rice (variety BRRI dhan29) under DDSR system. Experiment 4
used seven water management options namely, PTR-CI, PTR-AWD, DDSR (aerobic), DDSRAWD, DDSR (standing water from panicle initiation to heading), DDSR (standing water from
panicle initiation to grain filling) and DDSR(standing water from heading to grain filling) and
two rice varieties. All the Experiments were conducted at the Agronomy Field Laboratory,
Bangladesh Agricultural University, Mymensingh, while the Experiment-1 was also conducted at
farmers' fields in Dinajpur, Rajshahi, Tangail and Netrokona disdricts. Experiments-1 and 4 used
split-plot design while Experiments-2 and 3 were conducted in Randomized Complete Block
Design with three replications. Experiment-1 revealed that DDSR saved 51-63% irrigation
water and gave 10.20% and 33.97% higher yield and net benefit, respectively than that of PTRCI. In Experiment-2, the highest grain yield of both the varieties were obtained from 30 kg ha¹ seed rate (25
× 15 cm spacing). Experiment-3 exhibited that dry seeding at 5 cm depth and weed control by
application of pre emergence herbicides Panida (Pendimethalin) @ 2.5 L ha¹ supplemented with
one hand weeding at 20 DAS followed by panida application gave the best weed control and
yield performance. Experiment 4 showed that keeping of standing water from panicle initiation to
heading appeared as the best water management practice for dry direct seeded Boro rice. The
study concludes that dry direct seeding followed by AWD is more water efficient and economic
than puddle transplanted conventional or AWD irrigation system for Boro rice cultivation. The
present study suggests that sowing of Boro rice seed in 5 cm depth at 25cm × 15 cm spacing
using 30 kg seed ha and weed control by application of Panida (Pendimethalin) at 2 and 20 DAS
(after hand weeding) and keeping 5cm standing water from panicle initiation to heading and
maintaining aerobic field condition for rest of the duration could be the best agronomic
management practice for obtaining maximum yield of dry direct seeded Boro rice.