Abstract
Thirteen male-sterile clones of rice (Oryza sativa L.) variety CTH-1 showing male sterility were isolated from the M2 generation. They were maintained clonally and evaluated for pollen and spikelet sterility over 58 periodical plantings under high and low temperature regimes at three locations, viz., Hebbal (Bangalore), Honnavile (Shimoga), and Mudigere (Chickmagalore), India. Clones 4, 6, and 10 showed 100% spikelet sterility when the temperature regimes were above 30°C. The sensitive stage, stamen-pistil primordia stage of Clones 4, 6, and 10 was around 23 days, 20 days, and 19 days before heading and critical sterility points were 35.5°C/23.0°C, 35.8°C/23.5°C, and 35.0°C/23.0°C, respectively. Analysis of the F2 generation of crosses between these three clones and four pollen parents revealed that the sterility of thermosensitive genetic male-sterile clones was under the control of two recessive genes.
