Vergara - 1976 - Physiological and morphological adaptability of ri

PHYSICS OF CONTROLLED ENVIRONLfF-INT AND PLANT GROWTH
l4‘)
to provide the maioritjr of the leaf tissue. After that adaptation period, the
experimental measurements were for growth periods of 7-10 days.
Temperature
The influence of temperature on plant responses appears well documented
(cg. Cooper and Tainton, 1968). This is largely because temperature was the
environment parameter shieh was technically the easiest to control. However
the apparent comprehensiveness of the experimental information. and the
widespread publications of curves showing the effects of different temperature
levels on the vegetative growth of various crop species, can be deceptive. Optimum
temperatures vary substantially for differing stages of crop development
Attention was first dravm to this principle by Went (I957) in his early results of
tomatoes in the “Phytotron.“ Further. there are substantial interactions between
temperatures at subsequent stages of development (e.g.; Wardlaw. 1970
Yoshida. 1973).
Yoshidas work in the Climate Laboratory added to this sector of understanding
for rice (Yoshida. 1973). These interactions and effects are also illustrated
from joint work between staffs of the Canberra Phytotron and the New Zealand
Climate Laboratory on studies tvith vaheat (Warrington et al., 1976). Table 4
illustrates clearly both the effects of different levels of temperature at various
stages of development and the effects of canjr-over between one stage and the
next.
These variations must be considered in collating a sufficient body of results
from xvhich generalizations for individual crops or for ranges of crops can be
made. Equally‘. the more clearly these temperature interactions with growth
stages, and their CElI‘I'§"-0V6l" effects. are understood, the closer we will be to
understanding the adaptation of crops to their environments.
Air and soil water
Climate Rooms at Palmerston North operate over a wide range of relative
humidity conditions. This capability" was utilized to check on the effects ofconstant
levels of vapor-pressure deficit. at various levels of temperature and light
intensity. on the ivatcr use of a range of plant species.
In all cases ?5—8O percent of the leaf area of the plants had been grotvn under
the treatment conditions for which each measurement was made. This allowed
prior adaptation of the growth form to the treatment conditions.
Table 4. Main-ear grain formation, wheat var. Gamenya.
Growth phase day Grain Grain Wt per grain
temperature’
I ll Ill (mg)
2O 15 20 66.4 4265 54,2
20 20 20 59.2 3394 513
20 25 20 19.7 1063 54.0
‘Phases I, ll, Ill correspond to vegetative development flower development, and post-anthesis develop
merit
From Warnngton et al. (1976)