The Study Of Irrigation Limits Of Overwintering Tomato In Heliogreenhouse Under Substrate Culture

Selected "Ou Dun" tomato cultivars as material and90%of field capacity as irrigationupper limit, this paper studied the effects of lower irrigation limits from40%to80%on thegrowth, the moisture of leave tissues, osmotic regulation substances, photosyntheticcharacteristics, yield and water use efficiency of overwintering tomato in heliogreenhouseunder substrate culture conditions, and designed to provide a theoretical basis for theestablishment of the irrigation system of tomato substrate culture. The results of this studywere concluded as follows:1. The yield, fruit weight and water use efficiency of tomato was increased first andthen reduced with the increase of water lower irrigation. Sugar acid ratio was high and thequality of fruit was good under the treatment with70%irrigation limit, the3indicatorsreached up to peak values, the yield was7379kg/667m³, fruit weight was138.4g and thewater use efficiency was38kg/m³, higher than the treatments with40%～50%in39.3%～26.2%,33.9%～18.8%and21.6%～15.7%separately.2. The irrigation lower limits with60%and70%of field capacity were beneficial tothe growth of substrate cultured tomato for the strong of plants, rapid growth, large numberof leaves, appropriate root-shoot ratio and large dry weight of plant which reached up to227.26g with the treatment at60%level and210.09g at70%level, higher than40%treatment in18.3%and9.4%respectively.3. The content of free water and the ratios of free and bound water of three samples atfull growth period treated with70%irrigation limit were higher than the others. comparedwith40%treatment, the free water contents were higher in7%,15.2%and22%, reached upto77.52%,78.81%,75.49%respectively, and the ratios of70%treatment were9.37,8.07and5.85equivalent to1.69,2.29and2.22times of40%treatment. Water potential andrelative water content treated with70%irrigation limit was significantly higher than the40%and50%treatment, while the cell concentration of leaves and water saturation deficit waslower, significantly. Comparisons of indicators showed that, treatment with70%irrigationlimit was in favor of maintaining normal cells of leaves, the moisture inside body wasenough and metabolic active. 4. The pro and soluble sugar content of tomato leaves treated with40%and50%irrigation limit was263.23μg·g^-1and16.16mg·g^-1, higher than the others significantly. Thecontent of MDA under40%irrigation limit was increased sharply because of the membranelipid peroxidation and higher than60%,70%and80%treatment in6.3%,28.3%and35.5%respectively. Irrigation with lower than60%field capacity, on the other hand, was causedsevere water stress to tomatoes.5. The net photosynthetic rate, transpiration rate, and Fv/Fm of the plant under thetreatments with70%and80%irrigation limits were significantly higher than the others, withhigher activity of photosynthetic system Ⅱ and stronger photosynthetic capacity.6. Based on the above indicators, irrigation with60%to70%of field capacityachieved the targets of high yield, good quality and water saving, should served as an idealirrigation system of tomato substrate cultivation.