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Title: Interactive effects of pH, EC and nitrogen on yields and nutrient absorption of rice (Oryza sativa L.)

Author
item HUANG, LIHUA - Northeast Institute Of Geography And Agronomy, Cas
item Liu, Xuan
item WANG, ZHICHUN - Northeast Institute Of Geography And Agronomy, Cas
item LIANG, ZHENGWEI - Northeast Institute Of Geography And Agronomy, Cas
item WANG, MINGMING - Northeast Institute Of Geography And Agronomy, Cas
item LIU, MIAO - Northeast Institute Of Geography And Agronomy, Cas
item Suarez, Donald

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/11/2017
Publication Date: 8/14/2017
Citation: Huang, L., Liu, X., Wang, Z., Liang, Z., Wang, M., Liu, M., Suarez, D.L. 2017. Interactive effects of pH, EC and nitrogen on yields and nutrient absorption of rice (Oryza sativa L.). Agricultural Water Management. 194:48-57. https://doi.org/10.1016/j.agwat.2017.08.012.

Interpretive Summary: Rice has been utilized as an initial crop during reclamation of saline sodic soils. Rice is very shallow rooted and is grown under flooded conditions, thus it is suitable for use during the reclamation process. Soil salinity and sodicity can not only directly restrain crop growth by osmotic and specific ion stresses, it also may reduce grain yield indirectly by impacting plant absorption of essential nutrients. Saline sodic soils in arid regions are also often at elevated pH, another adverse factor for plant growth. The objective of this study was to investigate the interaction of soil pH, salinity and nitrogen application on rice yield and nutrient absorption. We conducted a rice experiment in containers in a greenhouse. The soils were first leached with 9 target salt solutions of pH 7, 8 and 9 and electrical conductivity (EC) of 2, 6 and 10 dS m-1). Nitrogen application rates were 100, 200 and 300 kg N ha-1. Rice grain yield and shoot weight significantly decreased with increasing soil pH and increasing soil EC, and significantly increased with increased nitrogen application (P<0.001). However, at high EC and/or high pH, yield was not significantly increased by increased N. Thus, adequate nitrogen application is an important technical measure for improving rice yield and promoting nutrient absorption in rice of high EC soils but not of high pH soils where pH is the major limiting factor for rice production. Reduced N application without yield loss will increase grower profitability and minimize nitrate leaching to groundwater. These findings are of interest to producers and extension specialists growing rice under saline and sodic conditions or at elevated pH as well as researchers studying effects of combined abiotic stress on crop yield.

Technical Abstract: Soil salinity and sodicity can not only directly restrain crop growth by osmotic and specific ion stresses, it also may reduce grain yield indirectly by impacting plant absorption of essential nutrients. Ensuring adequate nitrogen is an important management aspect of rice production in saline-sodic soils. The objective of this study was to investigate the interaction of soil pH, salinity and nitrogen application on rice yield and nutrient absorption. We conducted a rice experiment in containers in a greenhouse. The soils were first leached with 9 target salt solutions of pH 7, 8 and 9 and electrical conductivity (EC) of 2, 6 and 10 dS m-1). Nitrogen application rates were 100, 200 and 300 kg N ha-1. Rice grain yield and shoot weight significantly decreased with increasing soil pH and increasing soil EC, and significantly increased with increased nitrogen application (P<0.001). However, at high EC and/or high pH yield was not significantly increased by increased N. High pH and high EC in soil significantly influenced the mineral nutrient content of rice shoots (P<0.05). Rice grain yield and the absorption of K+ and Ca2+ in shoots significantly decreased with increasing salinity and increasing shoot Na+. There was a significant positive correlation between K-Na selectivity and rice yield under high pH or high EC conditions (r2=0.46, P<0.001). Nitrogen application provided a positive response under control and pH 7 at all salinity values, and at pH 8 under low salinity only. There was no significant response to additional N under pH 8 and elevated EC and no significant response at pH 9 for all EC values. Thus, adequate nitrogen application is an important technical measure for improving rice yield and promoting nutrient absorption in rice of high EC soils but not of high pH soils where pH is the major limiting factor for rice production.