ABSTRACT.
Optimum nitrogen management enhances growth, antioxidant ability and yield performance of rice in saline soil of coastal area of China

Guanglong Zhu1, 2, 3, Yue Wang1, 2, Xiaoxu Shi2, 3, 4, Haitong Lu1, 2, Zhen Ren1, 2, 3, Yu Shi1, 2, 3, Xiurong Jiao1, 2, Muhi Eldeen Hussien Ibrahim1, 5, Ahmad Irshad1, 2, Wenbin Zhu4, Junbo Bian4, and Guisheng Zhou1, 2, 3*
 
Salinity is a growing problem worldwide and techniques are needed to mitigate this problem. Field experiments were conducted to explore the effects of optimum N management (NM) on growth, antioxidant ability and yield performance of rice (Oryza sativa L.) in medium saline soil in the coastal area of Yancheng City, Jiangsu Province, China, during 2016 and 2017. A salt tolerant rice genotype Nangeng 9108 and N fertilizer including urea (300 kg N ha-1) were used, six levels of NM were arranged (base:tillering:panicle initiation fertilizers = 0:8:2 (T1), 0:6:4 (T2), 0:4:6 (T3), 5.6:2.4:2.0 (T4), 4.2:1.8:4.0 (T5), and 2.8:1.2:6.0 (T6), respectively). NM significantly affected plant growth, antioxidant traits, yield and yield components of rice in saline soil. On average, grain yield, panicles and spikelets per panicles were prominently higher under treatments of applied basal fertilizer (TABF; T4, T5 and T6) than treatments of non-applied basal fertilizer (TNBF; T1, T2 and T3). The TABF produced a yield advantaged of 39.7% and 54.4% over TNBF in 2016 and 2017, respectively. Bigger panicles were formed under TABF, mean spikelets per panicle was 15.7% higher than TNBF in 2016 and 20.0% in 2017. The T5 produced the highest dry weight, grain yield, panicles, spikelets per panicle, activities of catalase, peroxidase and superoxide dismutase, soluble protein, soluble sugar and sucrose at each growth period. However, the highest grain filling percentage showed under T4 had 82% and 81% advantages in each year. These results suggest that applied basal fertilizer can enhance salt tolerance and grain yield of rice, and appropriate N management can alleviate salt stress and increase grain yield.
Keywords: Antioxidant ability, grain yield, nitrogen management, Oryza sativa, saline soil.
1Yangzhou University, Joint International Research Laboratory of Agriculture and Agri-Product Safety, Ministry of Education of China, Yangzhou, 225009, China.2Yangzhou University, Agricultural College, Jiangsu Key Laboratory of Crop Genetics and Physiology/Jiangsu Key Laboratory of Crop Cultivation and Physiology, Yangzhou 225009, China.3Yangzhou University, Jiangsu Co-Innovation Center for Modern Production Technology of Grain Crops, Yangzhou 225009, China.*Corresponding author (gszhou@yzu.edu.cn). 4Jiangsu Yanjiang Area Institute of Agricultural Sciences, Nantong 226000, China.5Sudan University of Science and Technology, College of Agricultural Studies, Department of Agronomy, Khartoum 13311, Sudan.