Yoshida - 1981 - Fundamentals of Rice Crop Science

88 FUNDAMENTALS OF RICE CROP SCIENCE
Table 2.11. Effect of shading at different growth stages on yield
and yield components of lR74782-6. a
Grain Filled 1000-
Sunlight yield Harvest Spikelets spikelets grain wt
(%) (t/ha) index (no./m 2 ) (%) (g)
Vegetative stage
100
75
50
25
7.1 1
6.94
6.36
6.33
0.49 41.6
0.48 40.6
0.51 38.3
0.51 38.1
88.9 20.0
89.9 19.9
89.5 19.9
84.3 19.8
Reproductive stage
100
75
50
25
7.1 1
5.71
4.45
3.21
0.49 41.6
0.47 30.3
0.40 24.4
0.36 16.5
88.9 20.0
87.8 20.3
89.4 19.5
89.4 19.1
Ripening stage
100
75
50
25
7.1 1
6.53
5.16
3.93
0.49 41.6
0.49 41.1
0.44 40.6
0.38 41.7
88.9 20.0
81.1 20.0
64.5 19.5
54.9 19.1
a Yoshida and Parao (1976).
2.15. Effect of solar radiation
at different growth
stages on grain yield of
IR747B2-6 (Yoshida and
Parao 1976).
In the tropics, solar radiation is higher in the dry than in the wet season.
Consequently, the dry season yield is usually higher. The excessively cloudy
weather during the wet season is often considered a serious limiting factor to rice
production in monsoon Asia. This conclusion is true when yields higher than 6 t/ha