Central Rice Research Institute Annual report...2011-12

Enhancing and Sustaining the Productivity of Rice Based Farming Systems
replications. The crop was established by spot seeding
with pre-germinated seeds at 15 cm x 15 cm spacing
during second week of January. Experimental results
revealed that the highest yield (5.78 t ha -1 ) was recorded
in the treatments where rice + Azolla dual cropping was
practiced with a fertilizer dose of 90:60:60 kg N, P 2
O 5
and K 2
O ha -1 along with Azolla (1 t ha -1 ) applied 12
days after transplanting (DAT). However, it was comparable
(5.67 t ha -1 ) with Azolla (1 t ha -1 ) + 70:50:50 kg
N, P 2
O 5
and K 2
O ha -1 . About 121% yield enhancement
was recorded in Azolla + 90:60:60 N, P 2
O 5
and K 2
O kg
ha -1 over control plots where no fertilizer was applied.
The benefit : cost (B:C) ratio was higher in the treatments
where chemical fertilizer was applied than the
rice +Azolla dual cropping.
Another field experiment was conducted to evaluate
the efficiency of different weed control practices in
wet direct-sown rice. The treatments consisted of different
herbicides viz., Pretilachlor + Safener (800 g ha -1 ),
Pyrazosulfuron ethyl (20 g ha -1 ), bensulfuron methyl
(60 g ha -1 ), Almix (metasulfuron methyl + Chlorimuron
ethyl at 4 g ha -1 ), Almix + Pretilachlor (4+450 g ha -1 )
and bensulfuron methyl + Pretilachlor (50+450 g ha -1 ).
These treatments were compared with mechanical
weeding (finger weeder) + hand weeding; hand weeding
twice (20 and 40 days after sowing) as recommended
practice, weed free and weedy check. The major
weed flora in weedy plots at 45 days after
sowing(DAS) were Cyperus difformis, Sphenoclea
zeylanica, Leptochloa chinensis and Marsilea quadrifolia.
Grassy weeds constituted 26%, sedges 45% and broad
leaf weeds 29% of the total weed population at this
stage. Tank-mix application of bensulfuron methyl+
pretilachlor (applied as post-emergent 18 DAS at 50 +
450 g a.i.ha -1 ) was found to be most effective for controlling
the predominant weeds (WCE 91%) and produced
comparable yield (5.67 t ha -1 ) with hand weeding twice
(5.77 t ha -1 ). The highest net return (Rs. 21,298 ha -1 ) and
B:C ratio of 2.30 was also recorded with the treatment
of bensulfuron methyl+ pretilachlor. There was more
than 43% reduction in the grain yield of rice due to
competition with weeds in weedy plots.
Cropping system analysis for Eastern India
using remote sensing and GIS
Prediction of rainfall surfaces from point data is
necessary for generating alternate rice based cropping
pattern maps. Deterministic interpolation techniques
create surfaces from measured points, based on either
the extent of similarity or the degree of smoothing. In
Fig. 26. South-west monsoon rainfall spatial map of
Ganjam district of Odisha
this study, geo-statistical interpolation methods were
used to estimate monthly (June-December), seasonal
(South-West and North-East Monsoon seasons) and
annual rainfalls of Odisha. Historical daily rainfall data
(1982 - 2008) were collected from 168 rain gauge stations
of Odisha for the preparation of spatial rainfall
maps.The spatial rainfall maps were generated using
ordinary kriging method and the Ganjam district spatial
map of South West Monsoon (SWM) rainfall is presented
in Fig. 26.
Evaluation of site specific management in rice
and rice based cropping system
Yield spatial variability study was conducted during
the dry and wet season in 4.8 acres of land in CRRI
farm. The site was marked by difference in gradient
with variable level of standing water due to rain (10 cm
to 30 cm). The rice-rice system was followed with variety
“Naveen” during dry and “Gayatri” during wet
season. The yield was recorded in the grids size of 20 m
x 20 m (total 48 grids), during the dry season the rice
CRRI ANNUAL REPORT 2011-12
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