Study On Effect Of Potassium Nutrition On Mechanism Of Photosynthetic Function Of Cotton Leaf

Potassium is one of the essential elements for crop growth and development, and is inorganic cation whichexists abundantly plant tissues. Large amounts of potassium were absorbed during the development ofcotton. The sensitivity of cotton to potassium in the soil was obvious. Cotton is first show a lack ofpotassium deficiency, while in the same soil other crops showed no symptoms. Xinjiang is Chinese majorcotton producing areas and soil has been considered the "K-rich". But with increasing the cotton yields andcontinuous cropping years, a lot of potassium were taken constantly away from the soil, so that the soilpotassium content was decreased. Currently, cotton development period is restricted by potassiumdeficiency in Xinjiang. The aim of this work was investigate the effect of potassium nutrition on the cottondeveloping and to reveal the mechanism of how potassium influences cotton yield, the results obtained canoffer an important strategy for enhancing the efficiency of activation stable production in cotton. Below arethe main results in this thesis.1. Choosing the conventional cotton varieties “Xinluzao13”,“Xinluzao33” and “Xinluzao45” asexperimental material, to determine the effects of different concentrations of potassium nutrition onthe cotton yield at the growth stage. The results show that Xinluzao45is more sensitivity topotassium deficiency in three cotton varieties. Potassium deficiency led to decreasing of single leafnet photosynthetic rate, stomatal conductance, maximal photochemical efficiency and potentialphotochemical efficiency, reducing significantly chlorophyll content and SOD activity, and PODactivity and MDA content increased significantly.2. The more sensitive cotton variety “Xinluzao45” was used, to study the cotton photosyntheticphysiological effects of potassium during cotton development. The results showed that potassiumdeficiency decreased a single leaf net photosynthetic rate, stomatal conductance, chlorophyll content,photochemical efficiency, potential photochemical efficiency and SOD activity, anthocyanin content,POD activity and MDA content increased significantly.3. The impact of potassium deficiency on the macroelement （K, Ca, Mg, P） and microelement （Fe, B,Mn, Zn, Cu, Mo） content in roots, stems, leaves, seeds of cotton were studied through settingdifferent concentrations of potassium nutrition. The results showed that The macroelement contentand microelement content of potassium leaf decreased significantly. When the potassium of wasdeficiency, the capacity of absorbing K, Ca, Mg, P, through cotton root, stem and leaf were decreased,and microelement （Fe, B, Mn, Zn, Cu, Mo） content was also significantly reduced. Consequently,Potassium can promote that plant absorbed the macroelement （K, Ca, Mg, P） and microelement, andimprove the content of plant nutrient elements.4. In this paper, different potassium level of P_N-Ci. response curve and nitrogen content weredetermined in order to investigate the effects of nitrogen content. The results showed that during thesame concentration of CO₂, the photosynthetic rate of potassium deficiency leaves was low. Whenthe CO₂concentration increased to500, P_Nwas no increase significantly with increasing CO₂ concentration, but the low potassium treatment and the control still rises slowly. Therefore,potassium deficiency leaves cannot use a high CO₂concentration In same potassium concentrationnitrogen content was the lowest in root, and the highest in leaf.