VEGETATIVE GROWTH - Cold Tolerance in Rice Cultivation - page 35

Table 9 Effect of low root temperature on the net assimilation rate (gm -2 d -1 ) of
rice plant under different humidity and root temperature.

Before LRT 25ºC During LRT Period

25ºC 13ºC

Humid
Dry

21.7 + 1.5
21.9 +1.5

15.9 + 0.6
15.3 + 1.5

16.3 + 0.8
14.8 + 0.3

16.5

16

15.5

15

14.5

14

Humid25 Humid13 Dry25 Dry13

Fig. 15 Changes of net assimilation rate with humidity and low temperature.

Thus, from the above fi ndings it is clear that dry matter
production, net assimilation rate as well as stomatal conductance
were reduced severely under dry cold climate. Humid cold
climate had some sparing effects on the vegetative growth of
the rice plants (Kuwagata et al. 2012) (Figs. 16, 17 & 18).

0.6

0.5

0.4

0.3

0.2

0.1

0

Humid 25C Humid13C Dry 25C Dry 13C

Fig. 16 Infl uence of humidity and temperature on stomatal conductance
(after Kuwagata et al. 2012).