Study On The Response Of Water Demand Signal Of Peach Tree To Irrigation Water And Micro Meteorology Environment

Fruit is not only a major pillar industries of China's rural economy, but also an important channel of raising income for the arid and semi-arid area and even the national farmers. The study is with 4 year peach tree which grow under a mobile rainproof canopy as test material, establishes 100%ETc (I₁), 75%ETc(I₂), 50%ETc(I₃) and 25%ETc(I₄) four different irrigation treatments and three reiterations. Through the study on the water demand signals under different irrigation water, such as peach flow rate, canopy temperature, discrepancy between canopy and air temperature, water consumption, changes in photosynthesis and other aspects of the determination and the outside air relationship between environmental factors, analyses the law of the response of water demand signal of peach tree to irrigation water and micro meteorology environment to provide a theoretical basis for the precise control irrigation of fruit trees. The conclusions were as follows:(1) The sap flow velocity of peach tree exists obvious daily variation and day after day change rule during different irrigations and the performance is that high water irrigation treatment which sap flow velocity is high and low irrigation water treatment which sap flow velocity is relatively low, the daily changing of sap flow velocity presents multi-peak curve characteristic under normal growth condition, moreover, it is obvious that sap flow velocity is lower in overcast than in sunny day. Besides, with the variation of relative humidity of atmosphere, the sap flow velocity presents the day and night's periodicity, the relative humidity drops, the sap flow velocity rise; otherwise, the relative humidity rise, the sap flow velocity starts to drop.(2) Canopy temperature and discrepancy between canopy and air temperature are the two important indexes of reflecting the peach water status. Both the canopy temperature and the discrepancy between canopy and air temperature of peach tree have the obvious diurnal variation in growth period, the canopy temperature and the discrepancy between canopy and air temperature change much more significantly in high irrigation water treatment than lower irrigation water treatment. Moreover, the canopy temperature is higher in sunny day than overcast and the daily variation of discrepancy between canopy and air temperature is also significantly greater in sunny day than overcast. The discrepancy between canopy and air temperature and 0-100 cm soil moisture content have a good negative correlation.(3) PAR has a big variation in arid or semi arid areas of early summer's sunny day. Changes in atmospheric CO₂ concentration are in a small range throughout the day; the curve changes up and down and is similar to the'double M'type. Pn, Tr and Gs all have notable change characteristics of single-peak curve under different irrigation water quantity treatments. The diurnal variation of Tr of peach tree has significant differences, but has the same change tendency basically. Different irrigation water to peach has great influence to Pn, general value significantly increases with the irrigation increases, and has obvious change, but when irrigation water is higher, Pn doesn't change significantly with the increase of irrigation water. Gs reduces with the quantity of irrigation and with different irrigation treatments more obvious differences, expresses as I₁>I₂>I₃>I₄. Gs has a basic similar live curve with Tr which illustrates that Tr controlled by Gs. Pn and Tr, Pn and Gs, Tr and Gs all have best correlation under I₁ and I₂ irrigation, suggested that I₁ and I₂ irrigation are favorable to the growth of peach.(4) WUE has obvious discrepancy under different irrigation treatments throughout the whole day and the overall performance is I₃>I₄>I₂>I₁. The average maximum of WUE appears in I₃ irrigation, explained that WUE achieves the best condition under I₃ irrigation treatment; The performance of LUE is I₁≈I₂>I₃>I₄, which shows that under the same conditions, the more irrigation the higher LUE is , but under a certain quantity of irrigation LUE will not be increased. From the above we can realize that I₂ treatment not only saves irrigation water, but also makes LUE reached an average maximum.(5) Peach water deficit treatment can improve fruit hardness which performance is I₂>I₃>I₄>I₁ and increase the final average fruit weight, but eventually yield is I₁≈I₂>I₃>I₄, which explain I₂ treatment can not only guarantee ultimate yield irrigation but also reduce irrigation water quantity and spending. What's more, water deficit treatment is useful to improve soluble solids content, titratable acid and sugar/aid. Different irrigation treatments produce a very significant impact to single fruit weight, colour, mouthfeel, Vc, sugar/acid and production, a significant impact to hardness, soluble solids content, titratable acid and little impact on fruit moisture content.