Agriculture Reference
In-Depth Information
In Hunan Province in China, where double cropping
of indica rice is common, low temperature damage on
seedlings during the nursery period becomes a main
problem in the fi rst cropping. Effect of low temperatures
(8, 11 and 14ºC) on the root growth and the root secretion rate
of the seedlings during raising stage of indica (Zhe9248, Xiang
24) Japonica I (Koshikikari) and japonica II (Taushinwase,
Hayayuki) are characterized by their low temperature
tolerances, suggests that root growth and the secretion rate of
indica and japonica I were always lower to those of japonica
II at each low temperature. In particular, it was noted that
secretion rates of indica and japonica I have decreased promptly
at treatment under 11ºC, but the secretion rate of japonica II was
relatively high even at 8ºC. The recoveries of the root growth
and secretion rate of exudates of japonica II were higher than
those of indica and japonica I. The degrees of recovery in both
traits revealed their close relationship with the quantity of
secretion rate of exudates under preceding low-temperature
condition. Based on these the low-secretion rate under low
temperature may be responsible for the interior recovery of
the root growth and the secretion rate of the exudates of indica
and japonica I in comparision to japonica II. These suggest
that the root membrane permeability is disrupted under low
temperature specially in indica, japonica I than japonica II
(Table 12).
Table 12
Means of percentage of saturated and unsaturated fatty acids of the
three classes of cold reaction obtained after evaluation of 44 rice genotypes at the
vegetative stage under low temperature treatments.
Cold reaction
Saturated fatty acids
Unsaturated fatty acids
28ºC
10ºC
28ºC
10ºC
Tolerant
28.7
28.6
72.0
72.6
Intermediate
29.1
29.2
72.0
70.5
Sensitive
29.3
31.8
71.1
68.7
(after Cruz et al. 2010)
