Phosphorus deficiency and its availability in excess affect physio-biochemical performance, yield potential, seed...

Phosphorus (P) is an essential macronutrient that is critical for plant growth and development. In rice cultivation, limited soil P availability is a major constraint that negatively affects root development, photosynthetic performance, and grain yield, potentially compromising the quality of subsequent generation seeds.

To evaluate the impact of phosphorus availability on plant physio-biochemical and agronomic performance and its influence on subsequent seed quality mediated by the (Phosphorous uptake 1) Pup1 QTL, two contrasting rice genotypes were used: Pusa-44 (P-deficiency-sensitive) and its near-isogenic line NIL-23 (P-deficiency-tolerant due to the introgression of Pup1). Plants were grown under varying Pi regimes: [low/deficient (4 ppm), optimum (16 ppm), and excess (32, 48, and 64 ppm)] in PusaRicH hydroponic medium. Physio-biochemical analyses revealed that NIL-23 exhibited a superior root system architecture and higher acid phosphatase activity under P deficiency, indicating enhanced P acquisition efficiency. Correspondingly, NIL-23 displayed improved agronomic performance, with a higher number of tillers and panicles, greater grain yield, and higher filled grain percentage per plant compared with Pusa-44. Seeds from NIL-23 also contained higher reserves of starch, protein, and crude fat under P-deficient conditions, highlighting the regulatory role of Pup1 in conferring P-deficiency tolerance. Pi availability in seed significantly influenced the performance, wherein NIL-23 seeds germinated faster, reached to 50% germination approximately 2.5 h faster than Pusa-44, and exhibited higher seed vigor indices and dry matter accumulation. Conversely, excessive Pi availability negatively affected agronomic performance and quality of seeds in both the rice genotypes.

Our findings demonstrate that the Pup1 QTL enhances P deficiency tolerance, agronomic performance, yield, and seed quality in rice. The results also highlight the importance of efficient and judicious use of phosphatic fertilizers to support sustainable rice production, contributing to Zero Hunger (SDG 2), Responsible Consumption and Production (SDG 12), and Climate Action (SDG 13).