INHERITANCE AND CHARACTERIZATION OF POLLEN FERTILITY IN PHOTOPERIODICALLY SENSITIVE RICE MUTANTS

Low pollen fertility mutants in the M(7) generation were identified in the field from ethyl methane sulfonate-treated material of the rice c ultivar M-201. M(7) plants exhibited low pollen fertility levels (2%-2 8%) with mean values 7.5-fold less than M-201. Pollen fertility increa sed 3 to 44-fold when the M(7) field plants were ratooned and grown in a growth chamber with a 12 hr daylength. High fertility of all F-1's was observed in crosses with normal and pollen sterile lines. Chi squa red analyses of five F-2 populations indicated that, depending on the cross, pollen fertility was governed by one to three recessive nuclear genes. Transgressive segregation for both low and high fertility was observed in all but one cross. A 19% to 66% increase in fertility of l ate tillers over main stems was observed in mutants under field condit ions. Interruption of the dark period with 5 minute treatments of red or far-red light resulted in altered fertility levels and suggested in volvement of phytochrome in regulation of pollen fertility.