Diallel analysis of kernel weight and grain‐filling traits in maize grown under contrasting nitrogen supply

Abstract

Understanding the inheritance of maize (Zea mays L.) kernel weight (KW) under contrasting nitrogen (N) supply is crucial for obtaining high KW across diverse N conditions. This work evaluated broad-sense heritability (H2), and general and specific combining ability (GCA, SCA) under contrasting N levels for (i) KW and kernel number per plant; and (ii) grain-filling traits represented by the duration of lag and effective filling phases, kernel growth and desiccation rates, maximum water content and volume, and moisture content at physiological maturity. A six-parent full diallel cross generated via Griffing?s method 3 was tested under high (N200) and low (N0) N supply for two years (Y). For the various traits: (i) F1 hybrid, and F1 by Y and/or N interactions were significant (P < .05); (ii) effects of GCA were significant at both N levels and higher than SCA effects (except for KW), which were important (P < .05) only at N200; and (iii) GCA was affected (P < .05) by the Y effect. For KW and grain-filling traits, H2 and GCA/SCA ratios were higher at N0 than at N200, suggesting low-N environments would be more advantageous for developing genetic selection. Lag-phase duration (LPD), kernel desiccation rate (KDR), and kernel maximum water content (KWCMAX) had higher H2 (≥.70) and GCA/SCA ratio than KW, particularly under N0. Thus, the highest KW hybrid (LP2×LP662) was composed of inbreds with high GCA for LPD, KDR and KWCMAX, revealing superior KW hybrids could be selected from the GCA of mentioned traits.