Effects Of Sand Dust Stress On Photosynthetic Characteristics Of Four Fruit Trees In Southern Xinjiang

This article set the leaves of paddan,walnut,apple and apricot in Southern Xinjiang as material,study the changes of photosynthesis characteristics under sand dust and shade cover treatment with a short time and a long time treatment.Based on the degree of solar radiation and shading time,short time sand dust cover treatment?treatment period was 50 minutes?were 3,6,8.8,15.8 and 18 mg?cm^-2 thickness respectively.The processing time of long time sand dust cover treatment were 9,18,27,36 d respectively,it were divided into mild dust cover treatment 3 mg?cm^-2 thickness,severe dust cover treatment 8.8mg?cm^-2 thickness.In this study,the changes of photosynthetic parameters such as net photosynthetic rate?P_n?,transpiration rate?T_r?,stomatal conductance?G_s?,intercellular CO₂ concentration?C_i?;fluorescence parameter such as chlorophyll content,initial fluorescence?F₀?,the PSII maximum photochemical efficiency?Fv/Fm?,non-photochemical quenching coefficient?NPQ?and photochemical quenching coefficient?qP?were studied on four kinds of fruit trees leaves under different dust stress.The results are as follows:?1?The P_n of paddan,walnut,apple and apricot leaves tends to be reduced with respect to the increment of shading rate under a short time sand dust and shade cover treatment.Under 99%shading rate,the P_n value of paddan,walnut,apple and apricot leaves in sand dust cover treatment group decreased 76%,95.3%,72.5%and 72%,respectively,compared non-dust cover treatment group.The changing tendency in the T_r,G_s and C_i of these four fruit leaves under two kinds of cover treatment groups are different from each other.?2?P_n value of paddan,walnut,apple and apricot leaves tends to be reduced with respect to the increment of treatment time under a long time sand dust cover treatment;P_n,T_r and G_s value of apricot leaves tends to be reduced with respect to the increment of treatment time under a long time shade cover treatment,those valves of other three fruit leaves under shade cover treatment groups were different from each other.Under dust stress,the decrement in net photosynthesis rate of paddan was caused by the common effect of stomatal and non-stomatal limitation,the photosynthesis of walnut and apple leaves was only affected by stomatal limitation,and it was effected by the limitation of non-stomatal in apricot leaves.?3?The Chlorophyll-a content and total chlorophyll of these four fruit leaves above goes down with respect to the increment of processing time in long time sand dust cover treatment group,however,the trend of Chlorophyll-b content was different.Under shade cover treatment group,Chlorophyll-a content,Chlorophyll-b and total chlorophyll of paddan leaves goes down with respect to the increment of processing time,change trend of chlorophyll in the other fruit trees was different.?4?In long time sand dust cover treatment group,the F₀ valve tends to be increased with respect to the increment of treatment time,in three kinds of leaves except paddan.The Fv/Fm and qP valves tends to be reduced with respect to the increment of treatment time,in all four kinds of leaves,however the NPQ valves tends to be increased.Under shade cover treatment,except walnut,F₀ valve tends to be reduced with respect to the increment of treatment time;the Fv/Fm and qP valves increased with respect to the increment of treatment time,in that three kinds of leaves.NPQ valve tends to be reduced with respect to the increment of treatment time,in that three kinds of leaves,except apricot.?5?Principal component analysis results showed that,anti-dust cover ability of four kinds of leaves are as follows:apple?apricot?paddan?walnut.