Physiological response of diverse rice genotypes to simulated aerobic, and nitrogen deficiency conditions under hydroponic culture

Abstract

AbstractDirect sown, aerobic cultivation of rice is becoming increasingly popular among farmers due to the impending water and labour shortage. Previous reports suggest a decrease in nitrogen use efficiency of aerobic rice crop in comparison to irrigated rice. Moreover, aerobic rice soils have high ratio of nitrate: ammonical nitrogen in comparison to submerged paddies. Thirty rice genotypes were screened under hydroponic conditions using two nitrogen treatments: T1 with high nitrogen (HN) in the form of NO3−and T2 with low nitrogen (LN). Relative biomass accumulation, total chlorophyll, and carotenoid content were used to evaluate N deficiency tolerance of the rice seedlings. Results showed a range in total chlorophyll content from 0.87 to 2.57 mg g− 1FW in the HN treatment and 0.80 to 2.12 mg g− 1FW in the LN treatment, with total biomass ranging from 0.05 to 0.46g in HN and 0.013 to 0.089g in LN treated plants. Based on relative biomass accumulation and total chlorophyll content, two top-performing rice genotypes (Vandana and APO) and one poor-performing genotype (RBPIO-226) were identified. These selected genotypes were then grown for one month under hydroponic conditions in three nitrogen treatments: T1 HN, T2 high ammonium (HA) (NH4+), and T3 LN. Genotypes Vandana and APO exhibited better root growth and increased density and length of root hairs in both HN and HA in comparison to RBPIO-226., and The detailed physiological analysis suggested a contrasting responses to nitrogen deficiency were in the selected genotypes.