effect of nitrogen application levels on growth of rice under drought stress conditions. The aim of this study was to investigate effects of nitrogen (N) application on root system development, photosynthetic rate and dry matter production under different drought stress conditions. The experiments were conducted in a line source sprinkler system creating a soil moisture gradient under a rain-out shelter | J. Sci. & Devel. 2015, Vol. 13, No. 8: 1388-1396 Tạp chí Khoa học và Phát triển 2015, tập 13, số 8: 1388-1396 EFFECT OF NITROGEN APPLICATION LEVELS ON GROWTH OF RICE UNDER DROUGHT STRESS CONDITIONS Tran Thi Thiem1*, Yamauchi Akira2 1 Faculty of Agronomy, Vietnam National University of Agriculture 2 Graduate School of Bioagricultural Sciences, Nagoya University Email*: tranthiem@ Received date: Accepted date: ABSTRACT The aim of this study was to investigate effects of nitrogen (N) application on root system development, photosynthetic rate and dry matter production under different drought stress conditions. The experiments were conducted in a line source sprinkler system creating a soil moisture gradient under a rain-out shelter. Three N -1 fertilizer treatments were applied: 60, 120 and 180 kg N ha . Nitrogen fertilizer was mixed well with phosphorus and -1 potassium fertilizer at the rate of 50 kg (P and K) ha and applied as basal dressing at 8 days after transplanting. The -1 obtained results showed that increase of N level from 60 to 120 kg N ha increased total root length and shoot dry weight of Nipponbare under severe drought stress conditions (25% w/w of SMC) conditions, total root length increased with increased N application leading to increase stomatal conductance and photosynthetic rate, and eventually increased shoot dry weight. In addition, only under well-watered conditions the relationship between the total root length and shoot dry -1 -1 weight was positive and notably significant at 120 and 180 kg N ha levels but not at 60 kg N ha level. The -1 experiment suggested that the nitrogen application levels of 120 and 180 kg N ha increased the dry matter production due to the increased total root length under well-watered conditions. Keywords: Drought, dry matter production, nitrogen, rice, root. Ảnh hưởng của mức đạm bón đến sinh trưởng của cây lúa trong các điều kiện hạn khác nhau TÓM TẮT Nghiên .
