Vergara - 1976 - Physiological and morphological adaptability of ri

TEMPERATURE AND LIGHT, REPRODUCTIVE GROVJTII AND RIPENING 189
merit by the sunshine hours may bring about some difficulty‘ in analyzing the
precise effects of light. because the number of sunshine hours does not directly
give the intensity of solar radiation. Munakata et al. (196?) reported, however.
that solar radiation was closely correlated with sunshine hours at a given location
or during the season. Also. Murata and Togari (1972) reported that the
correlation between sunshine hours and grain yield was as much as or even
higher than that betueen solar radiation and yield.
These climatic data were arranged on the basis of heading time, and averaged
at intervals of 20 days; for example, the temperature at [— 30] stage represents
an average for 2O days centering at 3U days before heading time. Figures 1 and 2
shmv that differences in temperature among location, are larger before heading
than after. Also these data seem to indicate that farmers of Japan are shifting
their rice cultivation or selection of varieties to get optimum temperature
conditions during the ripening period.
Analysis of data
'l'\\~'o procedures seem indispensable in analyzing the relations among climate,
yield components. and yield: one is the selection of growth stage and the other
is the mathematical model structure.
It may be necessary to determine the stage most sensitive to climate for individual
yield components. in order to obtain a good mathematical model.
Matsushinia (1957) found that yield components. such
spikelet number, percentage of ripened grain, and Weight of 1,000 kernels, were
Terrtparuture ("Cl
3O
26—
24 —
2B-
22-
20 —
l6 - » heading .
Q | t I | |
-6O -40 -20 O +20 o 4O
Siege from heading time (days)
l. Temperature pattern during ricegrowing period in
major rice producing prefectures of Japan (on the basis
of heading time). Temperature: mean value for 20 day's
at each stage {l96l—'72)