Characteristics of Photosynthesis Machinism in Different Peach Species Under Low Light Intensity

【Objective】The objective of this paper was to investigate the effect of weak light intensity on the leaf structure of various peach varieties under the solar greenhouse and to find the different response mechanism between them.【Method】Qingfeng and Maixiang were growing under the solar greenhouse,the low light was simulated with shade film to the three degree of 100% light intensity(CK),60%-70% light intensity(T1) and 30%-40% light intensity(T2). The net photosynthesis rate was measured,and the stoma morphic difference was observed,at the same time the chlorophyll content and leaf structure were analyzed.The chloroplast micro-ultrastructure of peach leaf under solar greenhouse were observed under microscope,and the effect of low light on the peach tree was compared.【Result】The results showed that as the light intensity was lower,the net photosynthesis rate(Pn) decreased,whereas the net photosynthesis rate of Maixiang increased at 10:00 o’clock and 14 o’clock respectively. The stoma density,stoma aperture and stoma conduct(Cs) were lower than that under normal light intensity;The total chlorophyll content(Chl(a+b)),chlorophyll a(Chl a) and b(Chl b) content increased,while the ratio of Chl a to Chl b decreased. With the shade degree aggravated,the leaf area,the ratio of leaf area to leaf weight,and the thickness of leaf up and low epidermis declined,it is the same for the thickness of sponge tissue. The ration of the palisesade tissue thickness to the sponge tissue enhanced. Growing under low light,the chloroplast number ascended,the grana lamella was thicker and the grana number was more than that under normal light intensity. The amyloid number per chloroplast in palisesade tissue of upper leaves declined,that was reversed of lower leaf.【Conclusion】All the data indicated that there were distinctive differences between the peach species in the Chl content,Pn,stoma characteristics,leaf structure,and the chloroplast structure.