Studies On The Photosynthetic Characteristics Of Sweet Cherry (Prunus Avium L.)

Many photosynthetic characteristics of three cherry varieties(Sato Nishiki, Stella and Napoleon Bigarreau) were studied ,such as diurnal change in net photosynthetic rate (Pn), the effects of the environmental factors on diurnal change in Pn,the effects of photosynthetic active radiation , C02 concentration and air temperature on photosynthesis of mature leaves et al.The net photosynthetic rate of different leafs locations, locations of canopy , leafs orientations, the concentration of Chla,Chlb and Chl(a+b) and specific leaf weight (SLW) were also studied .At last ,the stomatal density and the ratio of rail organize and sponge organize of leaves were discussed in this article. The results showed:1.Diurnal change in net photosynthetic rate (Pn) in cherry leaves was a typical "none-drop" bimodal curve which was determinately regulated by stomatal conductance.Although the environmental factors were very important to diurnal change in Pn,they did not change the type of the curve.2.the responsive curves of photosynthesis in mature cherry leaves to the change of photosynthetic active radiation ,CO2 concentration and air temperature can be described with quadratic equations,the specific shape of the curves varied with cherry varieties and the ecological factors concened.3.For the cherry varieties researched, the light compensation points were at 10-82umol.m-2.s-1 light saturation points at 970~1050umol.m-2.s-1; The CO2 compensation points were at 90-116 ul.L-1,and the CO2 saturation points atl030~1250ul.L-1; The suitable temperature scope were narrow which changed from 11℃ to 36℃, and best suitable temperature were between 23 ℃ and 25 ℃.4.On the same branch, the Pn of different leafs locations had a waving change, the middle and up-middle sites, leaves had high Pn values and high stablilities; The environmental factors and the developmental level of leaves were the main reasons of the waving change.In different location canopy and different leafs orientations ,there were different Pn, that indicating light might be one of the main reasons for different in Pn in location canopy and different leafs orientations.5.The concentration of chlorophyll (Chi) and specific leaf weight (SLW) affected Pn ,the more the Chl and the SLW ,the more the Pn, but in mature leaves , there was no interrslation between Pn and Chl. The morphological characters of leaves had important relations with Pn ; The stomatal density and the thickness of rail organize and sponge organize might be comparely important factors to leafs Pn, different varieties had the different effects.