Vergara - 1976 - Physiological and morphological adaptability of ri

Climatic influence on growth
and nutrient uptake of rice roots,
with special reference to the
growth unit theory
T. Yoshida
SUMMARY
he growth and activities of roots of lowland rice are inscparably related to
those of aerial parts. Therefore. the grcnflh and nutrient uptake of rice roots
are affected not only by the direct action of climatic lactors on them liut also by
the changes in growth and metabolism of aerial parts in response to light and
temperature conditions.
This review first blietly‘ describes the theory" on the emergence and elongation
of roots and of the shoot unit. which gives a morphological basis for the
root-shoot interrelationship in rice plants. Ne“. it discusses the effects of climatic
factors such as temperature and light intensity" on the growth and nutrient uptake
of rice roots on the basis of that theory
The difference between short- and long-tenn influences of temperature and
light intensity on the growth and nutrient uptake of rice roots is pointed out. and
some consideration is also given to the limitations of leaf analysis in determining
nutritional status under untavorable climatic conditions.
(iENERAl. THEORY ON EMERGENCE ANT) ElsONfiATlON OF
ROOTS IN LOWLAND RICE
ln cultivation practice it is empirically recognized that root development together
with root activities greatly affects the grain yield of rice. Difficulties are
encountered, however. in determining either the extent or the total activities of
roots in situ. They arise from two causes. First. a rice plant. in its tintogeny’.
successively initiates and sustains from hundreds to a thousand roots that grow
mostly in furrow soil but penetrate partly to subsoil through the plovrsolc.
These roots attain a depth of more than several lO‘s of centimeters. As a result.
the root system of rice. at its completion. presents a fully developed mass of
roots in a quite complicated network. Second. the system includes roots of
different ages with different activities and functions.
T. Ytllflldfl. Division of Plant Nutrition. National Institute of Agricultural Sciences. Nishigahara.
Kita-ku. Tokyo», Japan.