Vergara - 1976 - Physiological and morphological adaptability of ri

TEh-[PEREYFLTRE AND LIGHT. REPRODUCTIVE GROWTH AND RIPENING
R volue
t O
QT I | t a
-6O -4O -2O O +20 +40
Stage from heading time (days)
l2. Time course of multiple correlation coeffient of
grain yield. Model: modified type III. l962—7l data. 20
prefectures (n "I 160).
The correlation diagram between actual and estimated values of ripening
grade is shown in Fig. ll. The fit was 0.880 (n = 160).
GRAIN YIELD AND CLIMATIC FACTORS
The relationships between the grain (kernel) yield and climatic factors may be
stipposed from the previous results about spikelet and ripening grade.
The time course of sensitivity to climatic factors for grain yield, as expressed
by the R is is shmvn in Fig. l2. Three peaks are found at [—45], [— 20]. and [ — 20]
stages. These stages correspond to those obtained in the spikelet production
and ripening grade.
The functional relation between grain yield and climatic factors at [—45]
and [+20] stages was also similar to that in the spikelet production and ripening
grade. Ilowever. at [—20] stage when both spikelet production and ripening
grade are seriously affected by climate. this functional relation was different
from that in the spikelet production and ripening grade. Figure l3 Sh0\\"S the
regression curve of these jtrield components and grain yield on the temperature.
as expressed by ratio to each maximum. at [—20] stage. The temperature curve
of grain yield shows that this curve in a lower temperature range up to 23°C
is similar to that of ripening grade. but the curve in a higher range over 23°C
is similar to that of spikelet production.
The grain yield was estimated by the following equation. tvhich has the
climatic data at four stages. the [+0] stage (heading stage) and the above three
stages: