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

Table 26. Rhizosphere P concentrations (mg kg -1 ) of the rice cultivars planted to the soils of different P status
grown under flooded conditions
NaHCO 3
-P*
NaOH-P*
21 DAT Panicle Flowering 21 DAT Panicle Flowering
Rice Cultivars initiation initiation
Khuntuni soil (P-deficient)
IR28 7.4 ab 5.7 c 5.3 b 25.5 b 19.0 b 17.0 b
IR36 7.8 a 7.8 a 6.6 b 28.0 ab 23.0 a 20.6 a
Dular 7.0 b 6.6 b 6.2 a 30.2 a 23.6 a 22.5 a
Ranital soil (P-medium)
IR28 13.9 a 12.1 b 12.3 a 30.6 b 28.6 a 24.5 a
IR36 14.2 a 13.3 a 11.7 a 34.3 a 26.8 a 23.0 a
Dular 13.8 a 12.5 b 11.7 a 32.3 ab 23.8 b 22.8 a
CRRI soil (P-sufficient)
IR28 28.6 b 25.6 a 23.6 a 71.7 a 54.1 b 49.7 a
IR36 30.0 a 25.5 a 23.6 a 66.2 b 57.0 a 50.3 a
Dular 26.7 c 24.5 b 22.3 b 61.6 c 52.4 b 45.7 b
CV (%) 2.6 4.8
Comparison S.E.D. LSD (P=0.05) S.E.D. LSD (P=0.05)
2-G×S×V 0.3 0.7 1.4 2.8
* Mean of four replicate observations
In a column under each soil type, mean followed by the common letter are not significantly different (P< 0.05) by
Duncan’s Multiple Range Test (DMRT). DAT: Days after transplantation; G: Growth stage; S: Soil type; V: Variety
cific regulation of biosynthesis and release of root exudates.
Results showed that rice cultivars releasing tartaric,
malic, citric and acetic acids could extract P from
strongly absorbed soil P fraction, thereby increasing
native soil P utilization efficiency. In all the three soil,
Olsens P were more (ranged from 7.0 to 30.0 mg kg -1 ) at
21 DAT when the acid secretion in the root exudates
were maximum (Table 26).
Nitrogen-Variety trials
In order to find out the production potential of selected
AVT-2 rice cultures and their response to varying
levels of nitrogen viz., 50, 100 and 150 percent of
recommended dose of N, two trials were conducted in
different rice ecosystems during wet season 2011. In
AVT-2 (Early) transplanted trial, two early cultures IET
21401 and IET 21637 were tested against standard
checks Sahbagidhan and Tulasi along with local check
Vandana. The culture IET 21367 gave highest grain
yield of 4.24 t ha -1 and was comparable to other tested
cultures including checks. These tested cultures responded
significantly up to 60 kg N ha -1 .
In AVT-2 (ME) aerobic, the tested culture IET 21680
produced significantly higher yield (4.52 t ha -1 ) over
the checks Rasi (4.02 t ha -1 ) and IR-64 (3.34 t ha -1 ) and
responded significantly up to 80 kg N ha -1 .
Development of Production Technologies
for Aerobic Rice
Development of agro-management practices
for enhancing crop and water productivity in
aerobic rice
A field experiment was conducted with three irrigation
water (IW) depths (25, 50 and 75 mm) in main plots
and three IW/CPE ratios (0.8, 1.0 and 1.2) in subplots
and replicated thrice to optimize the irrigation schedule
in aerobic rice cv. Apo. Grain yield of aerobic rice
reduced significantly with increase depth of irrigation
from 25 to 75 mm but increased with increase in IW/
CPE ratio from 0.8 to 1.2 (Fig. 19). However, irrigating
the crop with higher IW depth and IW/CPE ratio recorded
significantly higher grain yield over lower IW
depths and IW/CPE ratio. Highest grain yield of 3.34 t
ha -1 with irrigation water productivity of 0.61 kg grain
m -3 of water was recorded when aerobic rice was irrigated
with 25 mm of water at IW/CPE ratio of 1.2. The
number of effective tillers decreased by 21.2% with increase
in irrigation water depth from 25 to 75 mm but a
62 CRRI ANNUAL REPORT 2011-12