Evaluation of CIMMYT Maize Inbred Lines for Low-Phosphorus Tolerance under Field and Hydroponic Conditions in the North Eastern Hills of Meghalaya India

Phosphorus is a critical nutrient for plant growth, and its limited availability in acidic soils represents a major abiotic stress threatening agricultural sustainability. Developing cultivars tolerant to low-phosphorus conditions is an environmentally friendly strategy, as excessive phosphorus fertilizer use can be detrimental to the environment. This study employed both field and hydroponic screening to identify maize inbred lines with contrasting tolerance to low-phosphorus conditions, aiming to develop high-yielding, phosphorus-efficient cultivars. Hydroponic screening using modified Hoagland’s solution (low phosphorus: 2.5 × 10 ^− 6 mol L ^− 1 KH₂PO₄; normal phosphorus: 2.5 × 10 ^− 4 mol L⁻¹ KH₂PO₄) was conducted to assess traits such as shoot and root length, fresh and dry weight, and root-to-shoot ratio. A significant increase in root fresh weight, despite no notable change in primary root length, suggests that the tolerant inbreds may adopt a strategy of lateral root proliferation rather than elongation of the primary root. Based on the low-phosphorus tolerance index (LPTI) and low-phosphorus performance index (LPPI), genotypes were classified into four categories. Genotypes VL181019, VL20213, VL175994, and VL236956 were identified as tolerant and good-performing, whereas VZL22777, VL1885, and VL109138 were categorized as sensitive and poor-performing. The overlap of tolerant and sensitive lines across field and hydroponic conditions emphasises the reliability of early-stage hydroponic screening as a cost-effective method for genotype selection. The identified inbred lines represent valuable genetic resources for future breeding programs aimed at developing high-yielding, low-phosphorus-tolerant maize cultivars, thereby contributing to sustainable agriculture and long- term food security.