Effects Of Irrigation Regimes On Rice Yield And Quality Under Straw Returning

Up to present,many researchers have carried out a large number of studies on the effects of straw returning technology and water-saving irrigation technology on the tillering dynamics,dry matter accumulation dynamics,grain filling rate,yield and rice quality of rice respectively,but there are few reports on the combination of straw returning technology and different irrigation regimes.Therefore,in this study,one conventional irrigation regime（flooding irrigation）and three water-saving irrigation regimes:intermittent irrigation,controlled irrigation I（water layer 30mm）and controlled irrigation II（water layer 15mm）were set up under the condition of straw returning to the field to explore the impact of irrigation regimes on the growth and development,grain-filling rate,yield and quality of rice,in order to define a reasonable water-saving plan,it can provide reference for the selection of reasonable irrigation regimes under the condition of straw returning,and also provide theoretical reference and technical support for the cultivation of rice with high yield and high quality in the cold region of Northeast China.The experiment was carried out in Heilongjiang modern agricultural demonstration area of Heilongjiang Academy of Agricultural Sciences,and the test materials were Longdao 21,Longdao 22,Longdao 27 and Longdao 31.The results show that:1.In the aspect of rice growth and development,under the condition of straw full returning to the field,three kinds of water-saving irrigation regimes can increase the number of tillers in the middle and early stage of rice to a certain extent,significantly can reduce the rate of tillering and ear formation,and reduce the plant height in the middle and late stage of rice to a certain extent;in addition,straw returning to the field-three kinds of water-saving irrigation could increase the dry matter accumulation in the leaves in the middle and early stage of rice,and the control irrigation II was beneficial to rice dry matter accumulation of stem and sheath in the middle and early stage.2.In the aspect of grain-filling rate,three kinds of water-saving irrigation can reduce the initial growth potential（R₀）to a certain extent,intermittent irrigation and controlled irrigation I can increase the average grain-filling rate(F_mean)and the maximum grain-filling rate(F_max)to a certain extent;intermittent irrigation and controlled irrigation I can extend the time to reach the maximum grouting rate(T_max),while controlled irrigation II can reduce the time to reach the maximum grouting rate(T_max),the intermittent irrigation can shorten the active grouting period（D）,and the controlled irrigation I and controlled irrigation II can prolong the active grouting period（D）.3.In terms of rice yield and its components,three kinds of water-saving irrigation can significantly increase the 1000-grain weight of rice,and intermittent irrigation can significantly increase the yield,while control irrigation I and control irrigation II can reduce the yield by 1.52%and 10.89%respectively.4.In terms of water use efficiency,among the four irrigation regimes,control irrigation II can achieve the maximum water use efficiency of irrigation,control irrigation I can achieve the maximum comprehensive water use efficiency.5.In terms of rice quality,compared with flooded irrigation,three kinds of water-saving irrigation can improve rice processing quality,rice appearance quality and rice cooking and eating quality in different degrees,among which intermittent irrigation can significantly improve rice appearance quality and cooking and eating quality,control irrigation I can significantly improve rice appearance quality,however,the improvement effect of three water-saving irrigation regimes on nutritional quality is not obvious.In conclusion,intermittent irrigation and controlled irrigation I are the optimal irrigation regime when straw is returned to the field in full amount,considering rice yield,water use efficiency and rice quality.