Zhang He;Li Yan;Meng Ya-li;Cao Nan;Li Duan-sheng;Zhou Zhi-guo;Chen Bing-lin;Dou Fu-gen

Texas A&M AgriLife Res Ctr Beaumont, Beaumont, TX 77713 USA;Nanjing Agr Univ, Key Lab Crop Physiol Ecol & Prod Management, Jiangsu Collaborat Innovat Ctr Modern Crop Prod, Minist Agr & Rural Affairs,Coll Agr, Nanjing 210095, Jiangsu, Peoples R China

couple stress;soil relative moisture content;soil conductivity;photosynthesis;growth stage

In the coastal saline soils, moisture and salinity are the functions of groundwater depth affecting crop growth and yield. Accordingly, the objectives of this study were to: 1) investigate the combined effects of moisture and salinity stresses on wheat growth as affected by groundwater depth, and 2) find the optimal groundwater depth for wheat growth in coastal saline soils. The groundwater depths (0.7, 1.1, 1.5, 1.9, 2.3, and 2.7 m during 2013-2014 (Y1) and 0.6, 1.0, 1.4, 1.8, 2.2, and 2.6 m during 2014-2015 (Y2)) of the field experiment were maintained by soil columns. There was a positive correlation between soil moisture and salinity. Water logging with high salinity (groundwater depth at 0.7 m in Y1 and 0.6 m in Y2) showed a greater decline towards wheat growth than that of slight drought with medium (2.3 m in Y1) or low salinity (2.7 m in Y1, 2.2 and 2.6 m in Y2). The booting stage was the most sensitive stage of wheat crop under moisture and salinity stresses. Data showed the most optimal rate of photosynthesis, grain yield, and flour quality were obtained under the groundwater depth (ditch depth) of 1.9 m (standard soil moisture with medium salinity) and 2.3 m (slight drought with medium salinity) in Y1 and 1.8 m (standard soil moisture with medium salinity) and 2.2 m (slight drought with low salinity) in Y2. The corresponding optimal soil relative moisture content and conductivity with the 1:5 distilled water/soil dilution, in the depth of 0-20 cm and 20-40 cm in coastal saline soils, were equal to 58.67-63.07% and 65.51-72.66% in Y1, 63.09-66.70% and 69.75-74.72% in Y2; 0.86-1.01 dS m(-1) and 0.63-0.77 dS m(-1) in Y1, 0.57-0.93 dS m(-1) and 0.40-0.63 dS m(-1) in Y2, respectively.