M. Ohe et H. Mimoto, EFFECTS OF THE TIME OF DEEP-WATER TREATME NT ON GROWTH AND LODGING RESISTANCE IN JAPONICA TYPE PADDY RICE (ORYZA-SATIVA L.), Nippon Sakumotsu Gakkai Kiji, 67(2), 1998, pp. 153-158
Recently sometimes deep water is used as a growth control technique in
rice cultivation in Japan. To make clear the proper treatment for gro
wth control, we studied five deep-water treatments (30 cm depth) which
were different in start time and period:plot A-1, from productive til
ler number determining stage to internode elongation starting stage;pl
ot A-2, to heading stage; plot A-3, to ripening stage; plot B, from in
ternode elongation starting stage to ripening stage; and plot C, from
heading stage to ripening stage. In plots A-I: A-2 and A-3, the percen
tage of fruitful culms improved and basal internode diameter increased
greatly compared to that of the control ( 5 cm water depth maintained
). However the breaking strength of basal internodes decreased as the
treatment period became longer (plots A-2 and A-3). This weakening cou
ld be explained by the development of lysigenous aerenchyma and thin c
ortical fiber in the internode tissue. In plot B, no improvements were
observed in the percentage of fruitful culms and yield components as
compared with the control. But remarkable reductions in breaking stren
gth and spindly growth were recognized in the basal internodes. The re
duction in strength could be explained by the thinness of the cortical
fiber and fundamental parenchyma, and a remarkable development of lys
igenous aerenchyma. In plot C, little influence of treatment was obser
ved on growth habit. These results indicate that treatment which start
s from the productive tiller number determining stage to internode elo
ngation starting stage has a possibility for rice growth control.