Vergara - 1976 - Physiological and morphological adaptability of ri

TFMPERAJITRE AND ‘mcaranva GROXKWH 177
Fertility mam W.)
I00
20—
NI
O |\ L I I 1 I l l
o_l' t0 l2 l5 rr t9 2| 2a
Water
ternpamtuw t°Cl
7. Protecting efTeet of the temperature of deeply irrigated
water on rice plants at the meiotic stage (Nishiyama
et a1. 1969).
Variety Sowing time Cultural temperature
(day-night)
H, Hayayllki 1967.3 25-l9‘”C
H; Hayay-"uki 1963.8 26—l9"’C
N, Norin 20 1963.3 2649C
l\-_ Nurin 20 1968.8 26—l9"C
(Water depth. 21 cm.)
grown under different environments. Environmental temperatures before and
after the critical stage influence the degree of sterility which is induced by cool
temperatures at the critical stage (Ito. 1971). Furthermore, the probability of
fertilization ‘was over 9O percent when as few as 2O ptvllen grains were shed on a
stigma (Togari and Kashiwakura. 1958). Each ofsix anthers in a normal spikelet
has more than 1.000 pollen grains. Hence. the causal relation from cool telnperature
at the young mierospore stage to the fertility stage is very complex. and
this widens the dispersion in fertility.
Many agricultural problems are highly complex. Scmpulous caution is
needed for analyses of those problems.