| In recent years, scale planting of fruit trees have a tendency to increase yearby year in northern hill region. The ultimate goal for fruit farmers planting appleis to get a large number of high-quality fruit. As we all know, more than90%ofdry matter fruit are formed by photosynthesis, thus photosynthetic rate of fruittree is a prerequisite of it’s yield and quality. At the same time, soil moisture isindeed one of the main factors affecting the photosynthetic rate of fruit trees.While, water storage pit irrigation method is a new method suitable forirrigation of fruit trees, The distribution of soil moisture under this method has afeatures what is deep large and surface small; This peculiar distribution of wateris bound to affect the photosynthetic rate of fruit trees, thereby affecting theyield and quality of fruit. Therefore, the study of apple photosyntheticcharacteristics with the impact of factors under water storage pit irrigation cannot only to predict the photosynthetic production in this mode of irrigationinitially, but also can provide a theoretical foundation for water storage pitirrigation’s universal. This study is significant both for theoretical and practical. Combining field experiments with theoretical analysis, this paper studiedapple photosynthetic characteristics and it’s relationship with impact factorsunder water storage pits irrigation, the main findings are as follows:1. The variation of net photosynthetic rate for apple treeThe law of diurnal variation of net photosynthetic rate(Pn) for apple tree issingle peak in tree growth period most of the time, peak presented between9:00～11:00am; Optical radiation reached the annual maximum in august, fruitnet photosynthetic rate showed a bimodal law, peak value and the second peakappeared in9:00am and15:00pm, net photosynthetic rate appeared valley inthe13:00as photoinhibition. Curve of net photosynthetic rate in annual cycleexhibit bimodal law, fruit net photosynthetic rate peak value appeared in Augustor September as strong light radiation intensity; Because smaller CO2concentration in atmosphere, the valley of the seasonal variation occurs in July.2. The contrast of net photosynthetic rate for apple tree under differenthandlingBy comparing the law of diurnal variation and seasonal variation atdifferent pit depths and different irrigation, it can be found that netphotosynthetic rate in pit60cm deep was significantly higher than the pit of40cm deep; and full irrigation conditions also largely higher than the non-fullirrigation. By comparing the ordinary ground water irrigation and water storagepit irrigation, we can find that compared with ordinary ground water irrigation,net photosynthetic rate under water storage pit irrigation was significantly higher. Meanwhile, environmental conditions were not conducive to the synthesis ofphotosynthesis in the September and October, the gap of net photosynthetic ratebetween them will more obvious.3. Correlation analysis between net photosynthetic rate and single factor ofapple treesBy the analysis of correlation and regression, the conclusions is that themost relevant factors changes with the seasons. In the early time fruit formedinitial, mainly factors witch affect net photosynthetic rate is the intensity ofoptical radiation, intercellular CO2concentration and transpiration rate; In thelate stage the process of fruit enlargement, the mainly associated factors isintercellular CO2concentration and optical radiation intensity.4. Through a clear relationship of fitted curve between net photosyntheticrate and single factors, the photosynthesis model is established between it andintuitive affecting factorsThis paper used the way of theoretical analysis with data fitting, establisheda non-linear model between net photosynthetic rate and intuitive impactfactors(Optical radiation intensity, atmospheric humidity, CO2concentration andair temperature) of apple tree, It’s convenient to calculate the photosynthesiswhile theoretically convincing, at the same time fitting results are satisfactory. |
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