Hydroponic experiment for identification of tolerance traits developed by rice Nagina 22 mutants to low-phosphorus in field condition

Abstract

Development of phosphate (P)-deficiency tolerant rice cultivars is constrained by lack of suitable, reproducible and consistent seedling stage screening methods in breeding programs. This study reports screening and characterization of M5 mutants derived from an ethyl methane sulphonate treated population of rice cv. Nagina 22 (N22) in low-P field (soil Olsen P 1.94 - 2.01 mg kg-1; alkaline Vertisol; pH 7.94) for high yield. The present study showed that seedling growth responses such as increase in root weight, root length, root / shoot weight and dry weight in P-deficient medium can be taken as indices of low-P tolerance in mature plants in field. Total phosphorus content in seedlings showed an inverse relationship with total phosphorus content and low-P tolerance in mature plants in field. But phosphorus content in seeds and acid phosphatase activity in the seedling stage were positively correlated with survival and seed set in low-P field. In low-P field, plant height correlated most with yield per plant and number of productive tillers in mature plants was highly correlated with tiller number at vegetative stage. These mutants (NH776, NH710 and NH719) have agronomic importance because of their ability to grow and give higher yield than N22 in P-deficient field.