Hydroponic based technique, a rapid method of screening for phosphorus use efficient maize genotypes

Abstract

Low phosphorus availability poses major constrain to crop yield in many Indian soil types (acidic, alkaline and calcareous). Therefore, modern cereal genotypes, like, the single cross maize hybrids is dependent on external application of high dose of phosphate for optimum production. Plants are capable of utilizing only less than 20% of the applied phosphorus and unutilized phosphate results in environmental degradation via algal bloom and eutrophication. Therefore the development of maize hybrids having high phosphorus use efficiency (PUE) may significantly contribute toward sustainable maize production with low environmental footprint. High PUE hybrids can be developed if we have high phosphate use efficient inbred lines for hybrid development. In this endeavor, a hydroponic based method of screening for low phosphate stress tolerance in tropical maize has been standardized by changing concentrations of various nutrients in Hoagland’s solution. Forty inbreds were evaluated for PUE using optimized hydroponic culture under glass house condition. Maize inbreds were grown hydroponically under optimum (1mM KH2PO4) and deficient (5µM KH2PO4) phosphate conditions for 22 days. The solution was regularly aerated by aquarium pumps and was replaced after every 3 days. Plants were harvested and observations were recorded on all important shoot and root physiological parameters, viz., fresh weight, dry weight, length, stem girth, shoot:root ratio etc. On the basic of phosphorus deficiency symptoms and physiological data, high (BML-5) and low (BML-10) PUE lines were identified. The phosphate content in high PUE line root and shoot was 0.155 and 0.068 µg P/g of dry weight biomass, respectively, in phosphate stressed condition. However, in low PUE line it was 0.033 and 0.022 µg P/g of dry weight biomass in root and shoot, respectively, in phosphate stressed condition. High PUE line could be utilized in breeding programme for developing PUE hybrids and to study molecular mechanisms playing role for phosphate stress tolerance.