Analysis of effects of trifluoromethanesulfonamide in sorghum inbred lines and their derived hybrids

In sorghum [Sorghum bicolor (L.) Moench], development of male‐sterile versions (A‐lines) of the seed parents (B‐lines) is a tedious and time‐consuming process limiting opportunities for the improvement of new seed parents. Assessment of the value of a potential new seed parent requires testcross hybrid evaluations, but because of male fertility of these lines, conventional methods are inadequate to generate hybrid seed required for testing. Mechanisms to reduce the number of lines that require sterilization would be beneficial. The chemical gametocide trifluoromethanesulfonamide (TFMSA) was evaluated for its potential applicability to generate testcross hybrid seed. To study the effect on inbred line productivity, foliar applications of 25 mg of TFMSA were made to a select set of male‐fertile B‐lines and were compared to the corresponding untreated male‐sterile A‐line. Trifluoromethanesulfonamide induced near‐complete male‐sterility and allowed for testcross hybrid seed production across a range of genotypes. Comparison to untreated B‐lines indicated an average 3‐d delay in flowering and a 13‐cm reduction in plant height. Furthermore, average seed weight per panicle (productivity) was reduced by 8 g. Comparison of testcross hybrids produced by TFMSA induced male‐sterile lines and cytoplasmic male‐sterile lines did not reveal any significant and meaningful differences between the hybrids derived from both sterility systems. Moreover, inbred lines produced hybrids that ranked consistently in both systems. These results show TFMSA can affect productivity of treated inbred lines, but not the derived hybrid, which demonstrates that TFMSA can be used to produce hybrids for evaluation prior to investment in sterilizing of these lines. Core Ideas Trifluoromethanesulfonamidene (TFMSA) application can delay maturity and reduce plant height and productivity of sorghum inbred. TFMSA treatment to inbred had no significant effects on derived hybrid. TFMSA is an effective gametocide for producing sufficient quantities of pure testcross hybrid seed.