Vergara - 1976 - Physiological and morphological adaptability of ri

456 CLIMATE AND RICE
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2. Relationship between relative growth rate of leaf area, LRGR. and the percentage
total nitrogen content of leaf blades. N, of rice plants grown in different
years (Miyasaka et al. 1974). The correlation coefficients for Akita (A) and
Chikugo (B) were 0.947 and 0.887. respectively. both significant at the 0.1 percent
level. Samples taken at various growth stages are included, the dashed circles indicating
those corresponding to the 3-week period starting from transplanting.
Closed and open circles represent dilferent varieties.
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seems to exert an influence on LRGR at the very early period just after transplanting.
Let us consider the data from Chikugo (Fig. 2b). The dashed points
indicate data of the S-ivcek period starting at transplanting. It is evident that
these points diverge considerably from the general LRGR—N relationship.
Those for nonnal season culture (closed circles) especially, show" a higher LRGR
value at a given N value than those for early season culture (open circles).
I11 explanation of this phenomenon. it has been further found that there is a
high positive correlation, 0.803, significant at the l % level, between mean temperature
and LRGR when data are pooled for both seasons (Fig. 3). This supports
the earlier observation that LRGR is most heavily dependent on mean
temperature when comparison is made among different locations using samples
taken at the same growth stage.
It appears that the rate of leaf area development as expressed in relative
growth rate is most heavily dependent on two factors. ie. the mean temperature
(of various climatic factors) and the percentage total nitrogen content
of leaf blades (of various inner factors). This is true irrespective of location,
year. growth stage, and variety", so long as a good variety well adapted to the