Dey et al.
Table 2. Effect of nitrogen levels and time of homo-brassinolide application on leaf area index and crop growth rate of
hybrid rice
Treatments
Leaf Area Index (LAI)
CGR (g/d/m 2 )
20 DAT
40DAT
60DAT
80DAT
20 -40DAT
40-60DAT
60-80DAT
Nitrogen level (kg/ha)
N0*
0.83
3.43
4.05
0.96
4.5
8.4
6.5
N60
0.99
3.73
4.17
1.15
6.1
13.4
14.7
N120
1.15
3.97
4.36
1.41
6.7
14.6
14.2
N180
1.39
4.28
4.76
1.70
8.1
17.8
14.3
N240
2.00
4.71
5.43
2.01
9.6
20.6
14.4
SEm(±)
0.045
0.075
0.106
0.050
0.22
0.32
0.35
CD(P=0.05)
0.130
0.217
0.307
0.144
0.63
0.92
1.01
Time of homo-brassinolides application
AT
1.27
3.99
4.34
1.18
6.3
12.2
12.8
AT+PI
1.27
4.00
4.56
1.57
7.4
14.9
12.7
AT+PI+FI
1.28
4.08
4.75
1.58
7.3
17.7
12.9
SEm(±)
0.035
0.058
0.082
0.039
0.17
0.25
0.27
CD(P=0.05)
NS
NS
0.237
0.112
0.49
0.72
NS
and lowest number of tillers m -2 were recorded in
to flowering resulted in high CGR that caused
crop at only one spraying at active tillering (AT).
further increase in DMA during the reproductive
Similar type of result was reported by Bera and
period leading high crop productivity. The results
Pramanik (2013). Nitrogen level exerted significant
corroborate the findings of Peng et al. , (2002) and
effect on LAI, DMA and CGR in the hybrid at all the
Huang et al. (2008).
growth stages. Maximum LAI, DMA and CGR were
The highest values of LAI and DMA was recorded at
recorded in crop at high nitrogen level (N 240 ); but
the thrice spraying of homo-brassinolide (AT+PI+FL)
were comparable to those obtained at its immediate
and was significantly greater than what obtained
fertility level (N 180 ). Both the above nitrogen levels
at the one spraying of homo-brassinolide spraying
produced significantly higher values of LAI, DMA
(AT) at most of the growth stages. The highest CGR
and CGR than those recorded at lower nitrogen
value was recorded at the thrice spraying of homo-
levels (N 0 and N 60 ) at most of the stages (Tables 2 and
brassinolide (AT+PI+FL), but were comparable to that
3). Rice hybrid at low nitrogen (N 0 ) produced the
of the twice spraying of homo-brassinolide (AT+PI)
lowest values of LAI, DMA and CGR as compared
in most of the cases. The lowest values of LAI, DMA
to those at all other nitrogen levels at most of the
and CGR of both hybrids were produced by the crop
growth stages. Higher nitrogen levels (N 240 and N 180 )
at the only one spraying of homo-brassinolide (AT)
increased DMA by 41 to 110% over low nitrogen
at most of the growth stages (Tables 2 and 3). The
level (N 0 ) at different stages due to increased CGR.
results corroborate the findings of Rao et al. (2002).
Wang et al. (2001) noticed that moderate LAI (5.0)
functioning for longer duration was more important
Yield components
than maximum LAI functioning for short period
on influencing the crop productivity. High LAI at
Hybrid rice responded well to nitrogen level in
higher nitrogen levels functioning during tillering
improving the yield components. All the yield
820