Experimental Studies On Growth Characteristic And Water Requirement Pattern Of Kiwifruit Trees Under Micro-irrigation

On the basis of consulted relevant literature at home and abroad,and combining the practice of the production of kiwifruit in Guanzhong area of Shaanxi Province.Adopted the technical route of combining field experiment with theoretical research.Under the conditions of microspray irrigation and drip irrigation respectively,analyzed the influences of the irrigation moisture content low limits on the growth and physiological characteristics of kiwifruit trees,fruit quality,fruit yield,water use efficiency,water product function and water requirement regulation of the kiwifruit based on the dynamic change of moisture content of soil and then established the optimal micro-irrigation schedule of kiwifruit suitable for Guanzhong Area of Shaanxi Province.The main results obtained as follows:(1)Under the conditions of microspray irrigation or drip irrigation,the maximum of soil temperature at 8:00 appearance time was moved with the increase of soil depth.The soil temperature at different depths varies with the temperature of the atmosphere,and showed a general tendency to decrease first,and increase later,then decrease at last in one day,and showed a general tendency to decrease first,and then increase during the whole phenological period of kiwifruit.In the midday of summer,the microspray irrigation can rapidly reduce the temperature and increase the humidity of the field,and this effect will continue to a few hours after the end of the irrigation.(2)Under the conditions of microspray irrigation or drip irrigation,the moisture content of soil decrease first,then decrease with the increase of the soil depth after 24 hours of irrigation.The maximum value of moisture content of soil appeared on 30～40cm and 408～50cm depth under microspray irrigation and drip irrigation respectively.The soil moisture content of the planned wetting layer(0～60cm depth)decreased slowly at the germination-frondesce stage and fruit maturing stage,but decreased rapidly in the flowing and fruit-setting stage and fruit enlargement growth stag(3)Under the conditions of microspray irrigation or drip irrigation,the water requirement size and modulus relationship among each phenological phase of kiwifruit are:fruit enlargement growth stage>germination-frondesce stage>flowing and fruit-setting stage≈the fruit maturing stage,fruit enlargement growth stage is the key period of water requirement for kiwifruit.The water requirement of the whole phenological period and the daily water requirement rate increased with the rise of the irrigation moisture content low limits.The crop coefficient of kiwifruit increased first and then decreased during the whole phenophase.(4)Under the conditions of microspray irrigation or drip irrigation,growth indexes of kiwifruit tree(including shoot,petiole,leaf area index)and physiological indexes of leaf(including net photosynthetic rate,stomatal conductance,transpiration rate)were significantly increased with the rise of the irrigation moisture content low limits,but when the irrigation moisture content low limits was raised to 70%,the increased of these indexes are not significant with the rise of the irrigation moisture content low limits.The logistic model can better simulate the process of kiwifruit volume over time.When the irrigation moisture content low limits are the same,the growth and physiological indexes of kiwifruit under microspray irrigation is larger than that under drip irrigation.(5)Under the conditions of microspray irrigation or drip irrigation,yield,water use efficiency and net benefits of kiwifruit increased with the rise of the irrigation moisture content low limits,but when the irrigation moisture content low limits was raised to 70%,these indexes decreased with the rise of the irrigation moisture content low limits.(6)Under the conditions of microspray irrigation or drip irrigation,yield of kiwifruit first increased,and then decreased with the increase of the water requirement.The model of the fruit yield with the water requirement of the whole phenological period can be able to estimate yield of kiwifruit.The results of water sensitivity index of each phenological phase of kiwifruit solved by Jensen model showed that the fruit enlargement growth stage was most sensitive to the deficit of water,while the effect of water deficit on fruit yield was not significant in the fruit maturing stage,which was consistent with the actual situation.(7)The different micro-irrigation treatments was analyzed by multi-objective fuzzy optimization method,and the irrigation moisture content low limits of 70%was established to realize the water-saving,high yield,high quality and high efficiency of kiwifruit in Guanzhong Area of Shaanxi Province.The optimal irrigation scheduling of kiwifruit was 9 times of microspray irrigation during the whole phenological period in 2017(normal flow year),of which the germination-frondesce stage was 2 times,the fruit enlargement growth stage was 7 times,the irrigating quota on each application was range from 266.11 to 481.89 m3/hm2,and the irrigation quota was 3113.44m3/hm2.