Field Crop 2025, Vol.8, No.2, 51-60 http://cropscipublisher.com/index.php/fc 54 3.3 Role of male sterility in hybrid seed production Male sterility plays a crucial role in the production of hybrid sorghum seeds. The use of cytoplasmic male-sterile (CMS) lines allows for controlled cross-pollination, ensuring that the resulting seeds are hybrids (Pfeiffer et al., 2010; He et al., 2020; Sandeep and Biradar, 2020). This method eliminates the need for manual emasculation, significantly reducing labor and increasing the efficiency of hybrid seed production. Additionally, male sterility systems can be combined with modern breeding strategies to create novel cultivation models that enhance grain yield and ensure sustainable agriculture (Wan et al., 2021). The CMS system has been successfully utilized in various crops, including sorghum, to exploit heterosis and improve overall crop performance (Makanda et al., 2010; Pfeiffer et al., 2010; He et al., 2020). Table 1 Average heterosis and range of heterosis with number of heterotic crosses of parents and F1s in desirable directions in respect of quantitative traits in rabi sorghum (Adopted from Sandeep and Biradar, 2020) Sl. No. Characters Average heterosis (%) Range of heterosis (%) over No. of crosses with significant heterosis in desired direction over Better parent Standard check Better parent Standard check M 35-1 BJV 44 PKV Kranti M 35-1 BJV 44 PKV Kranti 1 Days to 50% flowering -2.87 -30.65 to -0.81 -25.86 to 6.03 -25.51 to 6.49 -29.22 to1.23 47 34 34 43 2 Plant height (cm) 6.36 -10.05 to 34.31 -18.27 to 10.99 -20.34 to 8.18 -22.21 to 5.64 17 08 05 02 3 Number of leaves 2.21 -38.46 to 40.00 -33.33 to 16.67 -33.33 to 16.67 -38.46 to 7.69 05 03 03 00 4 Panicle length (cm) 1.88 -47.45 to 26.41 -21.56 to 82.16 -33.54 to 54.33 -36.64 to 47.15 01 32 23 14 5 Panicle width (cm) -12.07 -41.61 to 6.33 -35.94 to 4.15 -53.20 to -23.91 -53.67 to -24.67 02 00 00 00 6 Primaries Panicle-1 11.03 -39.87 to 19.62 -34.48 to 39.31 -48.65 to 9.19 -50.78 to 4.66 05 19 01 00 7 Panicle weight (g) 12.56 -51.52 to 51.95 -46.88 to 69.13 -72.21 to -11.50 -72.47 to -12.33 14 20 00 00 8 Grain yield per plant (g) 4.07 -58.03 to 18.47 -52.61 to 52.41 -75.16 to -20.13 -74.96 to -19.47 02 13 00 00 9 100 seed weight (g) 40.61 -26.25 to 43.88 -23.38 to 83.12 -26.25 to 76.25 -30.59 to 65.88 14 21 19 09 4 Development of Male Sterile Lines 4.1 Criteria for selecting male sterile lines The selection of male sterile lines in sorghum is based on several key criteria. Firstly, the lines must exhibit complete and stable male sterility to ensure no self-pollination occurs, which is crucial for hybrid seed production. Additionally, the selected lines should possess desirable agronomic traits such as high yield potential, disease resistance, and adaptability to various environmental conditions. For instance, cytoplasmic male-sterile (CMS) lines like A3 cytoplasmic male-sterile 'Dale' and 'Wray' have been noted for their higher brix and greater stalk yield compared to their male-fertile counterparts, making them suitable candidates for hybrid development (Pfeiffer et al., 2010). Furthermore, the lines should be compatible with a wide range of restorer lines to facilitate the production of diverse hybrids (Mengistu et al., 2020). 4.2 Breeding strategies for developing and maintaining male sterile lines Breeding strategies for developing and maintaining male sterile lines in sorghum involve several approaches. One common method is the use of cytoplasmic-genic male sterility (CGMS) systems, where male sterility is controlled by both cytoplasmic and nuclear genes. This system allows for the easy maintenance of male sterile lines by crossing them with maintainer lines that possess the same cytoplasm but are male fertile. For example, the use of
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