| Tarim basin and its surrounding areas are the most serious regions of sand and dust weather disaster in China. The total days of sand and dust weather here can be150times annually and mainly occurred in the spring and summer. Sand and dust weather had brought huge loss to the local agricultural production because it is the fast growing season of local crops, vegetables and fruit trees. The field experiment was conducted in April2011to October2012in Korla in order to study the physical damage and chemical influence of dust on leaves of Fragrant Pear and to find efficient methods to reduce the losses of the disaster. Artificial control experiment was carried out to study the characteristic of dust covered on the Korla fragrant pear leaf and analyze physical damage of dust particles on leaves chemical composition for fragrant pear in Onsu, Xinjiang. It might provide the scientific basis for the study the mechanism of fruit tree leaves physiological metabolic response to dust stress in extreme drought condition. The main results as follows:1. The sand and dust weather (SDW) days of of Korla was on a declining trend from1971to2005and presented a rising trend from2005to2010. The SDW occurred most in1970s, and the occurrence days of dust, blown sand and dust storm were reached the maximum value in1971,1977and1971, respectively. The SDW days in2010were approximate to the average number of 1970s. The SDW occurred more in spring and summer,especially more in April and March; less in Autumn and winter, especially less in September. The SDW days had a significant correlation with the meteorological factors.2. The order of leaf dust retaining capability (DRC) of three township sampling points in Korla was Harayulghun> Shanghu> Puhui. The monthy value of leaf DRC were not increasing month by month. The order of total amount of natural descended particle (NDP) during the leaves growth period was Puhui> Shanghu> Harayulghon, which were also inconsistent with the distance of three sampling points to sand source (the distance were Shanghu> Harayulghun> Puhui). In addition, the average measure of the dust is3.40338mg/cm2。3. There were dust particle on the leaf from Harayulgon and the size of particles bigger than that from Puhui. Hence, the leaves of Harayulgon might suffer more hurt compared to Puhui. The leaf surface from Shanghu has some trichome. The leaf under natural condition, light sand cover (30%solar radiation shading), severe sand cover (50%shading) and zero sand cover treatments were conducted and all the treated leaves were scaned and analysised by electron microscopy. The particalce on leaf under zero sand cover and natural conditions were small, and the particle size and distribution of zero sand cover were relatively uniform, the shape was more approximate to globular shape, the surface was not completely covered by gunk and the fallling corneous layer was less; fragrant pear leaf surface was covered by a thin layer of gunk at natural condition, falling corneous layer were more bigger than zero sand cover, and the dust particle size, shape and distribution of the sand of the leaves surface were not as uniformity as zero sand cover codition. There was a significant comparison between the leaves under natural condition and severe sand cover by electron microscopy pictures:thick and dense layer of dust particles covered on the leaf surface under severe sand caver, which result in almost invisible by electron microscopy pictures; the fragrant pear leaves surface has less and smaller dust particles and gunk under natural condition, which cocked corneous layer and falling debris was visible by electron microscopy pictures. Weather-shack and cock pear leaf cuticle surface under zero sand cover condition is not obvious; corneous layer had tilted weather-shack and relatively uniform under the light sand cover; corneous layer is completely covered under severe sand cover; the pear tree leaf cock a little result of dry but with much falling debris under zero sand cover.4. The test separately determine natural dust, particles on the leaf and several kinds of main metal elements in the leaves and the content of ammonium ions of the sampling point. The content in the natural dustfall order from more to less are Ca> Mg> Fe> NH4+> Zn> Mn> Pb> Ni> Cu> Cd; the order of foliar adsorption particles content from more to less is Ca> Mg> Fe> NH4+> Zn> Pb> Mn> Ni> Cu> Cd; the order several kinds of main metal elements and ammonium ion contented the in the Korla fragrant pear leaves from more to less is Ca> Mg> NH4+> Pb> Zn> Fe> Cu> Mn> Ni and Cd was not checked out.There were a significant differences (p=0.012) between the influence of several kinds of metal elements and ammonium ions on the ion content in the natural dust and particles by the methods of subsequent analysis of variance and multiple comparisons. The influence of different ionic species on the content is very significant (p=0.0001). These results can provides some basic data for the follow-up research of the heavy metal pollution and mineral nutrition analysis of korla fragrant pear.5、The experiment also determined the several main anion content of sampling point, concluded several anion content in natural dust and particulate matter(from more to less):HCOO-> PO43-> F-> C2O42-> NO2-> NO3-> Cl-> SO42-; the main anion content of Korla fragrant pear leaves in order from more to less is HCOO-> F-> NO3-> PO43-> C2O42-> NO2-> SO42-> Cl-which have obvious difference with the sort of anion content in dust and particulate matter. By variance analysis, several kinds of anion were derived from the natural dustfall, particulate matter, or blade and had no significant influence (p>0.05) on the the ion content; Various of species had a very significant effect on the anionic content (p<0.01).These results can also provide some basic data for the follow-up studies of Korla fragrant pear physiological and ecological characters. |
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