Vergara - 1976 - Physiological and morphological adaptability of ri

454 ctnxuna mo RICE
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Mean olr tunporutun (‘Cl
I. Correlation between mean air temperature and the
relative growth rate of leaf area. LRGR. in young rice
plants grown at various locations (h-‘lflllfil and htlurata.
1970). Different varieties at seven stations are included.
measured period being during the 6 weeks starting from
transplanting in I967. The correlation ciretlicient is
0.8581. significant at the 0.1 percent level.
temperatures. However. the total number of tillers per IOU seedlings was highest
at 31 °C, the actual value being 30 for 16°C. 140 for 21 °C, 245 for 31 “C. and 210
for 36 "C.
Under natural conditions. daily average air temperature and water temperatu1'e
generally do not differ greatly. although there may be some time lag between
them. Thus. it may be concluded that the optimum air temperature for tillering
of rice is around 31 °C. It is expected that the higher the temperature, the more
active are both tillcring and leaf grovrth within the range lower than 31 “C. The
results shoivn in Fig. l can be well explained in this may.
Solar radiation and leaf area development
Since most of the ltxzatitinal differences in the rate of leaf area development at
the same growth stage of the plant are attributable to the difference in temperature.
it may be inferred that the influence of solar radiation and other climatic
factors is comparatively small. Solar radiation also could have had considerable