Study on gene action of yield and its attributes in rice (Oryza sativa L.) under phosphorus-deficient conditions using Griffing’s approach

Phosphorus (P) deficiency drastically limits rice production in tropical soils, necessitating the development of P-efficient varieties. The present study evaluated the combining ability of eight rice parents and their 28 F₁ hybrids, which were produced from a half-diallel cross, at the UBKV Research Farm in West Bengal during Kharif 2021–2023 under deficient P soil condition. The experiment was laid out in a randomized block design with three replications and genotypes evaluated for 14 yield related traits. Combining ability was analyzed using Griffing’s Method II, Model I, to estimate general (GCA) and specific (SCA) combining ability effects. Significant genetic variation was observed, with GCA exceeding SCA for traits like plant height and grains per panicle, indicating strong additive effects, while SCA dominated for P uptake and yield, suggesting non-additive contributions. Parents like MTU 7029 and Ranjit appeared as superior combiners, while crosses such as CR Sugandh Dhan 909 × BBII and Paolum Sali × Ranjit exhibited high hybrid vigor. Dominance variance surpassed additive variance across traits, favoring hybrid breeding strategies. These findings indicate prospective parents and crosses that can improve rice production and P-use efficiency in low-P soils, especially in the Terai Zone of West Bengal.