Random‐Type Sterility in Sorghum 1

Summary Study of the S 1 , S 2 , and S 3 generations of Sorghum bicolor (L.) Moench and S. sudanense Stapf. plants for the inheritance of random‐type (ra‐type) sterility revealed bimodal distributions when classified arbitrarily from 1 (excellent seed set) to 12 (no seed set). The first modal peak was observed at classes 2 or 3, while a second peak occurred at classes 8, 9, 10, or 11. Sterility classes 6 and 7 had the lowest frequency and appeared to be the break points. The distributions were very similar for classes 1 through 6, and 7 through 11. It appeared that the sterility observed in S. bicolor was quantitatively inherited and was different from that previously reported in sorghum. The narrow sense heritability estimate for this character was 0.43. Pollen stainability decreased with an increase in sterility. It underestimated sterility among higher sterility classes, but was a good indicator of sterility among more fertile classes, suggesting that male‐sterility was primarily involved. A negative association was observed between sterility and vigor during the same generation. Positive associations were observed for sterility between different generations and for vigor and height of the progeny in the same generation. The study of progenies from individual panicles of the same plant revealed that S 0 , S 1 , and S 2 plants had significant intra‐plant variation for ra‐type sterility. Plants with similar intra‐plant progenies suggested that the sterility trait followed mendelian inheritance. Variation in intra‐plant progenies suggested that within‐plant somatic variations were occurring.