Response of different rice varieties under low nitrogen
Student name: Ms Manisha Narula
Guide: Dr Sonika Gupta
Year of completion: 2015
Host Organisation: National Research Centre on Plant Biotechnology, New Delhi
Supervisor (Host Organisation): Dr Pranab Kumar Mandal
Abstract: Rice is one of the leading food crop in the world and is a staple food crop of over half of the world’s population. It was reported that rice utilize only 40% of applied nitrogen while the remaining 60% is lost to the environment. Hence, Nitrogen Use Efficiency (NUE) is a great concern for this important cereal crop. Certain key enzymes are responsible for utilizing the nitrogen, taken up by plants. If the role of these enzymes and their expression is known in relation to N deficiency, this would not only help in selecting efficient genotypes but also help in finding better alleles of genes which would help in achieving goal for breeding as well as basic studies for high NUE. In the present study, 2 rice genotypes, coded as RIV-001 and RIV-011 were evaluated. These genotypes were grown under N-optimum (40ppm) and N-stress (0.4ppm) conditions in hydroponics for 4 weeks. Various physiological parameters and two key enzymes namely, Nitrate Reductase (NR) and Glutamine Synthetase (GS) were assayed and their gene expression was studied in shoots by using semiquantitative PCR. Physiological parameters like chlorophyll content, shoot and root dry mass were decreased but these parameters were more or less similar in RIV-001 under both the conditions. Total root length and number of lateral roots were increased under N-stress condition in both the varieties but the increase was more in RIV-001. NR enzyme activity as well as gene expression were found to be decreased under decreased under low nitrogen. However, GS gene expression of two isoforms was noticed after PCR amplification. One of them showed upregulation whereas other one showed downregulation under N-stress.
Keywords: rice, Nitrogen stress, hydroponics
