Effects of different potassium supply and light intensity on photosynthetic capacity of oilseed rape leaves
To clarify the effects of potassium(K)supply and light intensity on leaf growth and photosynthetic characteristics of oilseed rape,a two-factor experimental design with K supply and light intensity was performed in this study,in which three levels of K supply were designed:severe K deficiency(0.03 mmol·L-1 KCl),mild K defi-ciency(0.09 mmol·L-1 KCl)and sufficient K supply(2.00 mmol·L-1 KCl),and two levels of light intensity were set:low light intensity(LL,～200 μmol·m-2·s-1)and high light intensity(HL,～400 μmol·m-2·s-1).The growth,gas ex-change parameters,chlorophyll fluorescence characteristics and mesophyll cell ultrastructure characteristics of oil-seed rape leaves under different K supply and light intensity under hydroponic conditions,in order to provide a theo-retical basis for the rational application of K fertilizer under changing environmental conditions.The results showed that K supply and light intensity significantly affected the growth of oilseed rape leaves.Under the same K supply,the leaf thickness and leaf dry mass per area of oilseed rape increased by 19.6%～24.3%and 57.1%～73.6%,respec-tively,under high light intensity treatment compared with low light intensity,while the net photosynthetic rate de-creased by 63.8%under severe potassium deficiency stress compared with low light intensity conditions.Severely K-deficient stressed leaves were photoinhibited under high light intensity conditions,and the actual photochemical efficiency,maximum carboxylation rate,maximum electron transfer rate and other key photosynthetic parameters were significantly reduced,and chloroplasts were poorly developed.While K deficiency led to a reduction in the pro-portion of intercellular spaces between mesophyll cells,and a decrease in mesophyll conductance,which in turn led to a significant decline in photosynthetic capacity of leaves.To sum up,K supply and light intensity jointly regulate leaf morphology and structure,affecting photosynthetic capacity.Insufficient K supply under high light intensity will seriously affect the growth of oilseed rape.Reasonable application of K fertilizer is conducive to improving the adaptability of rape to changes in light intensity and maintaining the stability of photosynthetic capacity.
万方数据
维普
