Vergara - 1976 - Physiological and morphological adaptability of ri

540 CLIMATE mo RICE
Concluding remarks
N. C. Brady
CONCLUDING
REMARKS
he objectives of this symposium were threefold: First, to examine W113i
is known about climate and rice both generally and specifically; second. to
review at least segments of work done on the responses of rice and other
cereals to different levels of climatic variables and to their interactions; and
third. to utilize and critically evaluate the genetic potential of the rice plant.
means of its protection from pests. and means of culturing it to increase yields
in a wide variety of climatic conditions.
From our point of vicvi-g the symposium has been most successful. The physical
scientists have given us at least a glimpse of the microclimate as it relates to
the performance of rice and other cereals. They have called our attention to
improved methods of measuring microclimate and have not tinly challenged us
to quantify microelimatie measurements but also the relationship between
microelimate in the field and crop response. They have nrarned us against overdependence
on controlled-environment approaches and urged a balanced
program wherein the measurement of field responses complements that in the
phytotroir
Attention has been called to the wide variation in climatic conditions to which
the rice plant is subjected. Temperature regimes from those at 49°N to the 30°S
latitude are being tolerated. along with the associated widely‘ different day
lengths. The moisture regimes discussed ranged from the dry upland conditions
ofparts of Asia and Africa through the controlled levels in normal paddy fields
and to the extremes experienced in the so-called deep-ivater rice-growing areas
of Thailand. Bangladesh. India, Indonesia, and Vietnam.
The biologists have discussed the effect of differences in climatic variables
not only on rice growth and yields, but also on the physiological processes upon
which these two end-points depend. Photosynthesis and respiration have had
their fair share of attention-some may feel more than is necessary. Likewise.
emphasis has been given to the effects of climatic variables on specific developmental
processes. In addition to identifying the gross effects of climate on rice
and other cereals. the program participants have shown the stages of growth in
which the effects of these climatic influences are most pronounced. Further,
they have reported that these effects differ depending on the climatic regime. Of
the climatic variables radiation intensity‘, duration. and range. temperature
differences. and water excesses and deficiencies have received most attention.
.\-'_ C. Braaj-a Director-General. Intemalional Rice Research Institute (IRRI). Los Bafios. Laguna,
Philippines.