Evaluation of genotypic variation for growth of rice seedlings under optimized hydroponics medium

Although rice (Oryza sativa L.) is a semi-aquatic plant, its growth in solution culture is often problematic. In commonly used rice hydroponics media, plants exhibited mild nitrogen deficiency, leaf tip burn, salt deposition, along with zinc and iron deficiency. Therefore, we aimed to optimize the nutrient media for growing rice plants taking into consideration the nutrient concentration, pH and ratio of NH₄⁺ to NO₃-nitrogen (N) and named it as ‘Pusa Rice Hydroponics ’(PusaRicH). PusaRicH contains higher amounts of macronutrients, significantly lower B, Mn and Cl and higher amounts of Zn than two commonly used hydroponics media, ‘Yoshida ’and ‘Kumura B'. The optimal ratio of NH₄⁺ to NO₃⁻-N in PusaRicH medium was 0.5 mM NH₄⁺ and 7.0 mM NO₃-with pH 5.0. The PusaRicH medium was validated by growing 100 diverse rice genotypes and it significantly outperformed the widely cited ‘Yoshida ’and ‘Kimura B'. Cluster analysis carried out on the squared Euclidean distance matrix of biomass and leaf area values of genotypes revealed four major clusters in all hydroponics medium. However, only PusaRicH medium resulted in ten gnotypes as good performers in comparison to other two widely cited media. Therefore, the optimized PusaRicH medium can be used successfully to grow rice seedlings in hydroponic system which will aid in screening large number of genotypes in breeding and other physiological experiments.