Effect of Nitrogen Application Rate on Root Morphological and Physiological Characteristics and Yield of japonica Rice in Region along the Yellow River

FU Jing; WANG Yuetao; YIN Haiqing; WANG Shengxuan; WANG Fuhua; CHEN Xiangong; WANG Ya; YANG Wenbo; BAI Tao

doi:10.15933/j.cnki.1004-3268.2017.07.003

Abstract：A field experiment was conducted to reveal the effects of nitrogen(N) application rate(0,180,210,240,270,300,330,360 kg/ha) on grain yield and root morphological and physiological characteristics of conventional japonica rice varieties Zhengdao 19 and Zhengdao 20 in region along the Yellow River.The aim of this experiment was to provide the theoretical basis for high-yield and highefficiency cultivation of rice.The results showed that shoot dry weight of Zhengdao 19 and Zhengdao 20 increased with the growth process,the root volume,dry weight,oxidation activity,indole-3-acetic acid (IAA) content,zeatin + zeatin riboside (Z + ZR) content,total absorption area and active absorption area increased first and then decreased with the growth process.The root volume,root dry weight,shoot dry weight and total root absorption area of two rice varieties increased with the increase of N application rate at the middle tillering stage,panicle initiation stage,heading stage and maturity stage;root oxidation activity,IAA content,Z + ZR content and active absorption area increased with the increase of N application rate at the mid-tillering stage and panicle initiation stage,while increased first and then decreased with the increase of N application rate at the heading stage and maturity stage,which all were the highest when the N application rate was 270 kg/ha.The yield of Zhengdao 19 and Zhengdao 20 increased first and then decreased significantly with the increase of N application rate from 0 to 360 kg/ha,the highest yields of Zhengdao 19 and Zhengdao 20 were 9.35 t/ha and 8.79 t/ha when the N application rate was 270 kg/ha respectively,which was significantly higher than those of other nitrogen treatments.The agronomic N use efficiency increased first and then decreased significantly with the increase of N application rate,the highest values of Zhengdao 19 and Zhengdao 20 were 17.0 kg/kg and 14.9 kg/kg when the N application rate was 270 kg/ha respectively,which was significantly higher than those of other nitrogen treatments.The partial productivity of N fertilizer decreased significantly with the increase of nitrogen application rate.In summary,when N application rate was 270 kg/ha,the root morphological and physiological characteristics of Zhengdao 19 and Zhengdao 20 were the best,the yield and agronomic N use efficiency were the highest,and Zhengdao 19 was better than Zhengdao 20.