Integrating Multi-Trait and Multi-Index Approaches to Identify Drought-Tolerant Tropical Maize Genotypes

Muhammad Azrai^1*Muhammad Aqil²Roy Efendi²Nining Andayani²Bunyamin Zainuddin²Marcia B Pabendon²Trias Sitaresmi²Muhammad Fuad Anshori¹Muhammad Riadi¹Muhammad Yasin²Reynaldi Laurenze¹Amiruddin Syam²Bahtiar Bahtiar²Suwardi Suwardi²Suwarti Suwarti²

• ¹Hasanuddin University, Makassar, Indonesia
• ²National Research and Innovation Agency (BRIN), Bogor, Jakarta, Indonesia

Drought stress poses a significant challenge to maize production in tropical regions by impairing growth and reducing yield. This study presents an integrated screening approach to evaluate drought tolerance and yield stability in tropical maize hybrids by combining multi-trait and multi-index analyses. Thirty-three maize hybrids were tested under both optimal and drought-stress conditions across two locations using a randomized complete block design. Morphological, physiological, and yield traits were recorded. Drought stress was imposed from 40 days after planting to milk stage, following International Maize and Wheat Improvement Center protocols. Advanced analyses including Principal Component Analysis (PCA) and hierarchical clustering were employed to capture variability and categorize the hybrids based on performance. To robustly assess drought tolerance, four distinct indices were calculated: the Stress Tolerance Index (STI), Stress Susceptibility Index (SSI), Yield Stability Index (YSI), and Harmonic Index (HI). The study further integrated these indices with key parameters such as grain yield, leaf angle, and shelling percentage using a multi-metric Venn diagram. The Multi-Trait Genotype-Ideotype Distance Index (MGIDI) was also applied to rank genotypes based on their overall performance across multiple traits, facilitating the identification of superior drought-tolerant hybrids. Strong correlations were observed between the drought indices and yield reduction under stress, with SSI and YSI values displaying R² values of 1.00 and 0.99, respectively. Additionally, STI and HI demonstrated significant associations with productivity under drought conditions, reinforcing their role in evaluating stress resilience. This integrated multi-metric framework identified six superior hybrids, GE13, GE17, GE21, GE26, GE29, and GE32, that exhibited strong yield stability and minimal reductions under drought stress. Consistently, MGIDI analysis ranked GE13, GE21, and GE32 among the top entries, highlighting their overall proximity to an ideal genotype across multiple traits. The convergence of results from both approaches reinforces the reliability of these three hybrids as elite candidates for drought-prone environments.