| Comparing to traditional agriculture, the relation of soil moisture supply-demand of traditional agricultural is changed. This situation aggravates the trend of soil dry layer and worsens the contradiction of the apple orchard moisture supply-demand. The research on apple orchard soil moisture consumption pattern is important for conducting scientific management. It can be used to simulate and forecast the orchard production and optimize the orchard insufficient irrigation system.This paper research the law of apple tree transpiration water consumption and fruit development and carries on the quantitative simulation according to field test data of the soil moisture content from 2003 to 2008 in hilly orchard in Yanan region. The main conclusions as followings:(1) The key factor restraining the high production and stable of apple is rainfall. The thesis analyzes the apple growth adaptability in different counties in Yanan and studies the efficient exponential of rainfall in different counties by using the method of fuzzy analysis. The average efficient index enlarged form 0.42 to 0.60. The maximum come up in Huangling county and the minimum is in Zichang county, Ansai, Zhidan and Wuqi county. The average value exceeds 0.5 in Huanglong, Luochuan, Fuxian and Ganquan county.(2) The soil moisture of slope orchard is quite different in different slopes, different slope positions, different tree-age, different planting density and different precipitation level year. The utilization of the soil moisture is changed with the soil depth during the growth period. The efficient utilization coefficient of the effective water increases with the soil depth decreases. The soil water between 0-2.0m is different in different slope direction. It accounts for 97% of total soil water consumption in sunny slope and only 67% in shady slope. The three forms of the Compartment Model can describe the change of soil moisture in different season.(3) The thesis evaluates the suitability of fruit tree under the soil moisture content quantity according to the root distribution and soil moisture content of different layer. The thesis ascertains the maximum utilization depth of the soil moisture is 3.0-5.17m. It is 3.0m only in the sunny slope, 4.5m in the shady slope, semi-sunny and semi-shady slope is 3.5m and 4.0m, the replat top is 4.5m.(4) The average water consumption is 675.5 mm in slope orchards. The water consumption mainly concentrates in 5 ~ 8 months, which account for the 64%. The variation of transpiration can be divided into the slow increase of initial growth period, quick increase of quick growth period, high water consumption in middle growth stage, transpiration decrease in mature stage and the low water consumption in dormant. The crop coefficients of apple tree in different growth stages are as following: it is from 0.33 to 0.45 in initial growth period, from 0.45 to 1.0 in rapid growth period, 1.0 in the middle growth period, until after the mature, crop coefficients by 1.0, form 1.0 to 0.33 in the mature stage. It is 0.33 in the whole over-wintering stage. The transpiration water consumption is not affected when the niche is high, the amount of which close to the amount of sufficient water supply, the moisture coefficient approximate 1. The moisture coefficient will degrade ass the soil moisture niche lower because of water stress.(5) The Richards model can better describe the growth of apple with time changes. The growth process of fruit diameter is significantly "S" curve on condition that the soil moisture is sufficient. The growth of vertical diameter is slower than the transverse diameter. The fruit grows quickly in young fruit stage and then is the fruit expending period in 60 days which is the greatest growth rate, finally is the slow growth stage in 75 days later. The key stage of the fruit diameter increase is the late of March to mid-July; the key stage of the fresh fruit weight added is late of June to mid-August. Water stress restrains the apple’s growth. The growth of the vertical diameter can reach 26.08mm and the transverse diameter reaches 32.05mm within one mouth without water stress. The growth of fruit will be restrained when the soil moisture niche is under 0.79 because of the water stress.(6) it should be replenished 75mm in wet year during May and 150.0mm in medium year during MAY and July twice and 225mm in dry year during June September and November respectively according to the typical year of hydrological. |
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