Temperature stress and Fertility Reversibility in Wild Abortive CMS
Lines of Rice for Quality Hybrid Seed Production
Abstract
CMS lines are highly sensitive to temperature change for the sterility
status. Determination of critical temperature for sterility breakdown in
wild abortive cytoplasmic male sterile (WA-CMS) lines under field
condition is essential for efficient seed production planning. CMS lines
IR58025A and IR68897A were grown at different dates of sowing to give
exposure to a series of temperature regime and day length at natural
field condition. At panicle initiation stages temperatures below 28.5°C,
the CMS lines were sterile and at temperatures below 30°C, the lines
became partially sterile. Above 30°C, the CMS line reverted to fertile.
The highest pollen sterility was recorded (98.3%) during the long day
condition while the lowest was recorded (43.5%) during the short day
condition indicating the effect of both temperature and day-length on
break down of sterility. Differential expression of floral characters
like panicle exertion and stigma was found with variation in
temperature. This simple field-driven technique can be successfully
employed to work out the functional temperature for fertility
reversibility which is of utmost importance for planning seed production
and maintenance of genetic purity of the hybrids. The techniques will
aid in designing seed production planning for hybrid rice in any
rice-growing area in the world