Male Sterility in Sorghum bicolor (L.) Moench Induced by Low Night Temperature. II. Genotypic Differences in Sensitivity

Abstract

Three genotypes of sorghum grown in controlled environments were compared for low temperature sensitivity during the leptotene stage of microsporogenesis. Treatment regimes imposed during this period were 21°C day and 14,11, 8 or 5°C night. A known sensitive hybrid (CK60 × Tx415) showed progressive reduction in pollen proline level, percentage starched pollen, and seed set with decreasing night temperature, indicating that sterility induction was a quantitative response to night temperature. The line 606, deveIoped at high altitudes in Mexico, was fertile under all treatment regimes. The hybrid CK60 × 606 was intermediate in response for pollen fertility, but pollen fertility was still sufficient to enable near complete seed set in all treatments. Factors considered important in breeding grain sorghums with low-temperature-tolerant microsporogenesis are discussed.