Analysis of heterosis in spring maize (Zea mays L.) germplasm to heat tolerance

This study evaluates 21 maize crosses through a series of 7×7 half diallel crosses initiated during the Rabi season in 2022 and planted again in the spring season of 2023 in Prayagraj, Uttar Pradesh. The objective was to assess mid-parent heterosis, heterobeltiosis, and economic heterosis based on the 20 characters analysed in maize. The mean sum of squares for all the characters suggested that parents were quite variable and a considerable amount of variability existed among the hybrids. Crosses P1×P7, P5×P6, P2×P6, P3×P5 and P1×P5 exhibited significant positive mid-parent heterosis values, whereas crosses P2×P6, P5×P6, P3×P5, P4×P5 and P1×P7 showed high heterobeltiosis values. Crosses P1×P7 and P2×P6 demonstrated significant positive economic heterosis. The hybrids P1×P7 and P2×P6 demonstrated superior performance in both yield and heat tolerance. The research provides valuable insights into developing maize cultivars resilient to heat stress crucial for enhancing agricultural sustainability in the face of challenges such as diminished yields, stunted growth and reduced productivity.