Vergara - 1976 - Physiological and morphological adaptability of ri

TEMPEILATIYRE AND LIGIIT_ REPRODUCTIVE GROWTH AND RIPENING 193
0.8
E
O5 — ./~ ‘f.
0.4 - I
"‘.|‘.‘
I
'1 ‘\‘
y
i‘! N \ ‘y
a
0.2 - ' *
“g/ 78"’
_
t’ F (sunshine)
‘u-— 2
Q
_
v
Y
b] t temperature)
v~__-v
'
0 I | | I | |
-6O -5O —4O ~30 ~20 -IO O
Stage {days} from heading time
4. Change in multiple correllatinn coefficient (R) and
regression coefficients (bfl and b'_ ) with the growth stage.
R. b’, and b’, were computed using the following model:
Y; = b,-I + b; + b»! + c.
(E which were calculated from data on the number of spikelets and climatic
factors at a given stage.
Figure 4 shows changes in the I? and standard partial regression coefficients
(i7. and 17,) which were used for respective evaluation of relative effects of
temperature and sunshine hours in the model type l.
The highest 1i (total sensitivity to climatic factors) was found at ]—40] — [-50]
stage when the rice plants tiller most actively. Also. the second peak in ti was
LIbStIR-Tid at [-20] stage when weak tillers die and spikelcts develop.
It was also found that the standard partial regression coefficient on temperature
(b-f.) had tvt-‘o peaks at [-50] and [-30] stage. While that on sunshine hours
(ti) had one peak at about [-45] stage. 'l'his suggests that the increase in tillers
correlates closely with both temperature and sunshine hours. whereas the number
of spikelets per panicle and decline in weak tillers may be more strongly
influenced by temperature than by sunshine hours.
Functional relation between spikelet production and climatic factors
Figures 5A and 5B indicate the regression curves of the number of spikelets on
thc temperature at [410] and [-20] stages. which wcrc more sensitive to climatic