Effects Of Different Moisture And Salinity In Soil On Physiological Characteristics In Cotton And Yield And Fiber Quality In Coastal Saline And Alkali Land

The field experiment was conducted in Dafeng,Jiangsu province(120°45’E,33°19’N)and the simulation experiment was conducted in Experimental Station of Jiangsu Academy of Agricultural Sciences in Nanjing(118°50’E,32°02’N)in 2013-2014.The cotton seed was CCRI-79.Experiment was setted 6 treatments in different groundwater depth,in Dafeng,1.0,1.4,1.8,2.2,2.6,3.0 m respectively.The treatments were disposed with salt in natural groundwater in coastal saline-alkali land.The Nanjing simulation experiment was added a minimum and maximum groundwater depth treatment,namely 0.6,1.0,1.4,1.8,2.2,2.6,3.0,3.6 m.In this experiment,NaCl was dissolved to keep a steady salinity level and the water depth in pool was controlled to be constant.The experiments were conducted to study the effects of different moisture and salinity level resulted from different groundwater depth on physiological characteristics in cotton functional leaves and yield and fiber quality in coastal saline-alkali land.The results provided a theory evidence for the comprehensive management of coastal saline-alkali land.The main results are as follows:1 Effects of different groundwater depth on salinity and moisture in soil and yield and fiber quality.As the water depth increased,SRWC and EC 1:5 decreased,the cotton plants suffered saline and waterlogging stress when groundwater depth was low and drought stress when groundwater depth was high.Changes of soil moisture and salinity in temporal and spatial were related to climatic conditions.In high temperature and drought,SRWC decreased and the value of EC,"5 increased.The value of SRWC of upper soil was smaller than that of the lower soil and the value of EC1:5 in the upper soil was higher than that in the lower soil.When in more rainfall,SRWC increased and EC1:5 decreased.SRWC of upper soil in space was smaller than that of the lower soil,while EC1:5 in upper soil was less than that in lower soil layer.In different moisture and salinity level,seed cotton yield and fiber quality reached a peak value when groundwater depth was in 1.6-1.8 m(Dafeng)and 1.8-2.2 m(Nanjing).2 Effects of different soil salinity and moisture on photosynthetic physiology in cotton functional leaves.Salt and water stress in different level reduced photosynthetic characteristics of the cotton functional leaves.With increasing of water and salt stress,Fv/Fm,ΦPSII,qP decreased gradually,and NPQ increased gradually.The two stress destroyed photosynthetic system Ⅱ in cotton leaves.The scale of solar energy absorbed.with photosynthetic pigments reduced which result in photosynthetic electron transfer of share,resulting in net photosynthetic rate decreasing.The key factor leading to the reduction of net photosynthetic rate turned to non stomatal limitation from stomatal limitation.3 Effects of different soil salinity and moisture on stress physiology characteristics in cotton functional leaves.Soil water salt stress promoted the production of reactive oxygen species(ROS)in cotton leaves.The activity of SOD,POD,CAT increased and the content of MDA and proline also increased simultaneously.When water and salt stress levels continued to increase,anti-oxidase activity decreased,membrane lipid was further damaged,the contents of MDA and pro line continues to rise.