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<p>Maize is one of the major cereal crops cultivated across the globe owing to its high production potential. Assessing and estimating the genetic diversity for various yield-attributing traits, along with resistance to turcicum leaf blight, is essential to enhance the potential of maize production in India. The present study was conducted to assess the genetic diversity and to group 336 maize inbreds into different heterotic groups. The experimental material was evaluated for yielding potential across two locations, viz., Bangalore and Hassan, during the rainy season of 2023 and 2024. The first two principal components (PCs) explained 67.70 per cent of total genetic variation. The PCA contribution plot indicated that the traits such as days to anthesis, days to silking, plant height and ear height recorded the highest contribution to the PC1, whereas the grain yield and turcicum leaf blight (TLB) disease response contributed more to PC2. K-means analysis grouped the genotypes into three clusters based on the scree plot, with 108, 90 and 138 genotypes into cluster I, II and III, respectively. The inter-cluster distance was the highest between clusters I and III. The genotypes present in the diverse clusters could be hybridized to get the desirable recombinants. The 336 maize inbreds were crossed with two testers, CML 451 (heterotic group B) and CL02450 (heterotic group A), to derive 672 test cross hybrids and the hybrids were evaluated at GKVK, Bangalore during the rainy season of 2025. Heterotic grouping was performed employing specific combining ability effects of grain yield (SCAGY), heterotic group’s specific and general combining ability (HSGCA), and general combining ability of multiple traits (HGCAMT). The HSGCA method of grouping divided inbreds into three heterotic groups A (113), B (113) and AB (110). Whereas, heterotic grouping based on SCA of grain yield grouped 168 inbreds into heterotic groups A and B, respectively. The HGCAMT method grouped 237 inbreds into heterotic group B, and the remaining inbreds (99) into heterotic group A. Further, the breeding efficiency for all three grouping methods indicated that the HSGCA method recorded the highest breeding efficiency. Validation of heterotic grouping methods was carried out by estimating mid-parent heterosis (MPH) for inter- and intra-group crosses. The SCAGY and HSGCA methods exhibited substantial increases in MPH for inter-group crosses (24.9% and 40.5%, respectively), whereas HGCAMT showed only a marginal increase (1.9%). This indicates that the HGCAMT method may be less effective in discriminating parental lines based on their heterotic potential. This article aligns with SDG 2 (Zero Hunger) of the UN Agenda for Sustainable Development.</p>

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Genetic diversity and heterotic grouping of newly developed tropical maize inbred lines employing multivariate clustering approaches and combining ability estimates

  • 期刊论文

  • 发表日期：

    2026年4月8日

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  • Udaya Shetty,
  • Muntagodu Shreekanth Sowmya,
  • Hirenallur Chandappa Lohithaswa,
  • Mallana Gowdra Mallikarjuna,
  • Siddaiah Chandra Nayaka

摘要

Maize is one of the major cereal crops cultivated across the globe owing to its high production potential. Assessing and estimating the genetic diversity for various yield-attributing traits, along with resistance to turcicum leaf blight, is essential to enhance the potential of maize production in India. The present study was conducted to assess the genetic diversity and to group 336 maize inbreds into different heterotic groups. The experimental material was evaluated for yielding potential across two locations, viz., Bangalore and Hassan, during the rainy season of 2023 and 2024. The first two principal components (PCs) explained 67.70 per cent of total genetic variation. The PCA contribution plot indicated that the traits such as days to anthesis, days to silking, plant height and ear height recorded the highest contribution to the PC1, whereas the grain yield and turcicum leaf blight (TLB) disease response contributed more to PC2. K-means analysis grouped the genotypes into three clusters based on the scree plot, with 108, 90 and 138 genotypes into cluster I, II and III, respectively. The inter-cluster distance was the highest between clusters I and III. The genotypes present in the diverse clusters could be hybridized to get the desirable recombinants. The 336 maize inbreds were crossed with two testers, CML 451 (heterotic group B) and CL02450 (heterotic group A), to derive 672 test cross hybrids and the hybrids were evaluated at GKVK, Bangalore during the rainy season of 2025. Heterotic grouping was performed employing specific combining ability effects of grain yield (SCAGY), heterotic group’s specific and general combining ability (HSGCA), and general combining ability of multiple traits (HGCAMT). The HSGCA method of grouping divided inbreds into three heterotic groups A (113), B (113) and AB (110). Whereas, heterotic grouping based on SCA of grain yield grouped 168 inbreds into heterotic groups A and B, respectively. The HGCAMT method grouped 237 inbreds into heterotic group B, and the remaining inbreds (99) into heterotic group A. Further, the breeding efficiency for all three grouping methods indicated that the HSGCA method recorded the highest breeding efficiency. Validation of heterotic grouping methods was carried out by estimating mid-parent heterosis (MPH) for inter- and intra-group crosses. The SCAGY and HSGCA methods exhibited substantial increases in MPH for inter-group crosses (24.9% and 40.5%, respectively), whereas HGCAMT showed only a marginal increase (1.9%). This indicates that the HGCAMT method may be less effective in discriminating parental lines based on their heterotic potential. This article aligns with SDG 2 (Zero Hunger) of the UN Agenda for Sustainable Development.