Nature of genetic control of the length and number of elongated internodes in deepwater rice under non-flooded condition

Inheritance of total length and number of elongated internodes in some varities of deepwater rice were studied in a 7 X 7 diallel (excluding reciprocals) by a procedure that does not require flooding. Estimates of combining ability and genetic component analysis showed highly significant additive and non-additive gene effects with preponderance of additive type. The high estimate of narrow sense heritability further supported the importance of additive gene effects. lalmagna and IR40905-11-3-1-5-2-21 were not always the best combiners. The significance of the gene distribution indicated the presence of gene asymmetry. The average degree of dominance was 8.83 for both total length and number of elongated internodes indicating partial dominance

Effect of water depth, seedling age, and day length on elongation induced by short-duration flooding treatment in rice

Experiments conducted on seedling age and different water depths revealed that short-duration, 7-day flooding of 3 week- old seedling was effective in assessing elongation potential in deepwater rice varieties. Water depths of 90-100 cm were sufficient to express elongating ability and 3-week-old seedlings gave better contrast between elongating modern varieties and non-elongating modern varieties. Maximum internode length was under short-day-length conditions while shortest internodes were obtained in the long day treatment. Internode elongation may be due only to the signal effect of day length or the shading effect on assimilation. Further experiments should be conducted to confirm these findings