Vergara - 1976 - Physiological and morphological adaptability of ri

478 cuxiivrs mo arcs
Spikclots (thousand/ sq m l
Spiketatst no lpariele)
5O 300
50L4F RADMTDV
71'MERAHRE
4O Z50 - 0
so 20o - °
20 I50 y-
lO IOO >-
‘I- I I l l
H. I l I
o I00 200 30o 400 s00 22 25 2e at
Solar rodiutionteol-erfiz-doyl
Mean tempemturetqil
4. (‘rrain number per square meter (JV) and solar radiation (S) in relation to daily mean
temperature during the period of 25 days before flowering.
In our field experiment. seasonal variation of average daily mean temperature
is narrow, ranging from 24° to 30°C. Therefore. it would seem likely that spikelet
number per unit amount of solar radiation vrould be a negative linear function
of the average daily mean temperature:
Sl-‘V Qr-(.-\'.. — t) (6)
With this approximation. we found a high correlation between spikelet number
per square meter (rY) and solar radiation during the reproductive stage and daily
mean temperature during the same period (Fig. 4). This relationship can be
written
This equation implies that spikelet number per square meter is positivefv correlated
with solar radiation during the reproductive stage. that is. 25 days before
flowering. and negatively with daily mean temperature during the same period.
The equation (7) is rewritten
N = S-fl!) = S(278 — 707!) (S)
The correlation coefficient between measured spikelet number and computed one
xvas 0.888“. The procedure we have used here is similar to that ofMurata {I964}
and Ilanyu et al. (1966) The difference is that while Murata. and Ilanyu et al.
examined climatic influence on ripening, we did so on spikelet fonnation.
Using 18.1 g for LOGO-grain weight and 86% for filled grains (the mean values
of the l9 crops in this experiment). we can estimate the grain yiield of the [R747
line planted at different times of the year.
Y = $(278—7.U7t) 4186 - l8.l ~ l0’! (9)