Effects of low phosphorus stress on photosynthetic and chlorophyll fluorescence characteristics of alfalfa with different root types
To explore the responses and adaptability of leaf photosynthesis and chlorophyll fluorescence of dif-ferent root-type alfalfas under low phosphorus stress in the first year and the following year,a pot experiment using three root types of alfalfa of creeping rooted Medicago varia Martin'Gongnong No.4',tap rooted M.sativa'Long-dong',and rhizomatous rooted M.sativa'Qingshui'as the experimental materials was conducted.The effects of low phosphorus stress on photosynthesis parameters,carotenoid content,chlorophyll content,and chlorophyll fluo-rescence parameters were studied.The results showed that the chlorophyll a,chlorophyll b,carotenoids and chloro-plast pigment content,photosynthetic and fluorescence parameters of alfalfa of different root types were reduced un-der low phosphorus stress,compared with the normal the decrease rate was between 2.9％～47.9％,2.1％～47.8％,8.1％～57.8％,2.6％～7.8％,0.5％～60.2％,and 1.1％～52.0％,respectively,indicating that non-stomatal factors limited the photosynthesis of alfalfa under phosphorus stress.The photosynthetic performance of alfalfa plants was weakened by the destruction of the photoreaction center of alfalfa plants under low phosphorus stress.The inter-cellular CO2 concentration,water use efficiency and non-photochemical quenching coefficient of alfalfa increased by 2.9％～12.2％,10.0％～96.5％and 5.7％～27.4％,respectively.The chlorophyll a,chlorophyll b,carotenoids,chloroplast pigment contents,net photosynthetic rate,stomatal conductance,and stomatal limitation value of rhizo-me alfalfa were most affected in the first year and the following year,which decreased by 47.9％,47.8％,57.8％,47.8％,37.5％,22.1％,19.8％,and 16.6％,24.5％,16.6％,19.0％,35.4％,54.2％,24.2％,respectively.From the point of view,tap rooted and creeping rooted alfalfa showed greater resistance to low phosphorus stress than rhizomatous rooted alfalfa.The correlation analysis further showed that the structure and physiological state of PSⅡ system in alfalfa leaves under low phosphorus stress were damaged,and chlorophyll was decomposed in large quantities,which inhibited photosynthetic electron transport and hindered photosynthesis.
国家科技期刊平台
NSTL
万方数据
维普
