Ngày nhận bài: 10-02-2017 / Ngày duyệt đăng: 03-04-2017 / Ngày xuất bản: 06-08-2025
Hydroponic and field experiments were conducted to evaluate the effect of three nitrogen (N) supplies and two N forms - ammonium nitrate and urea - on growth of rice plant under severe saline conditions. In hydroponics, two salt tolerant cultivars, Cuom and A69-1, were examined at tillering stage. Three concentrations of N - 1.4, 2.1 and 2.8 mM were applied in the Yoshida solution supplemented with NaCl at 113 mM. In paddy field under severe saline condition, six cultivars, viz. Cuom, Ngoi, Hom rau, A69-1, FL478, and IR28 were used to evaluate growth and yield at three N supplies, 45, 68 and 90 kg N ha-1. In hydroponic conditionplant dry weight, number of root tips, total root length, and SPAD value increased with ammonium nitrate concentration.In contrast, all these parameters as well as leaf specific area and N use efficiency decreased with urea concentration in both of cultivars. In the paddy field experiment, N forms and levels had no effect on grain yield, but N forms affected 1000-grain weight and number of panicles per plant, whereas N levels increased dry matter weight at dough-ripening stage with N applied. The use of reduced level of N fertilizer is suggested for rice under severe saline condition.
