Effects Of Irrigation And Plastic Film Mulching On Grain Filling Of Summer Corn And Their Relationship With Hormone Changes

Water is one of the most significant factor affecting crop growth. Plastic film mulchingcould alter the motion direction of water and decrease water evaporation during crop growth，which would keep water content of soil and then influence growth of summer corn. In orderto explore the effects of plastic film mulching and irrigation on summer corn growth, grainfilling as well as their relationship with hormone, a summer corn cultivar, Zhengdan958wassystematically studied through artificial water controlling experiments. Results are as follow:(1) With different irrigation under plastic film mulching, plant height, leaf area indexand chlorophyll content of corn greatly increase with the improvement of irrigation. With thesame irrigation condition (both270mm and300mm), plant height, leaf area index andchlorophyll content turned out to be PM>CK, while with240mm irrigation, leaf area indexand chlorophyll content of maize after spinning showed PM<CK.(2) Plastic film mulching could improve the water content of surface soil effectively.During summer corn growth period, water content of0-100cm soil under PM treatmentturned to be more than that of CK. During jointing and spinning period, water content of0-40cm soil gradually rose with the increase of soil depth while with soil of40-100cm, itturned to be the opposite trend. During mature stage, water content reached a peak at30cmfollowed by gradual decrease. According to TDR test, water content of0-20cm soil showedPM>CK under the same irrigation condition, C-300>C-270>C-240and P-300>P-270>P-240under the same plastic film mulching and conventional conditions, respectively.(3) Soil temperature of different layers (5cm,10cm,15cm,20cm and25cm) weremeasured regularly at eight o’clock. It showed that temperature of layer0-15cm of PM werebigger than that of CK during corn growth period. And it showed no obvious pattern amongthree different irrigation conditions.(4) Comparing with CK, grain filling of PM started quickly, speed of grain fillingincreased rapidly during the prior period and decreased quickly during later period. Under thesame irrigation condition, PM showed improved grain filling speed and grain weight ofsummer corn than CK. In terms of the grain weight, maximum and mean grain filling speedof different section of corn cluster (U, M and B), it showed that PM>CK with the same grain section under the same irrigation condition, that B>M>U with the same irrigation andagricultural conditions, and that high irrigation>medium irrigation>low irrigation with thesame grain section and agricultural conditions.(5) Water content affected that of ABA, Z+ZR, GAs and IAA in corn significantly.Endogenous hormone increased greatly with the increase of irrigation while release of ETHshowed the opposite trend. Under different treatment, content of ABA, Z+ZR and IAAshowed U>M>B in different grain sections during early and medium period of grain filling.Content of ABA, Z+ZR and IAA showed highly notable positive relevance to grain weight,maximum and mean grain filling speed, highly notable negative relevance to release of ETH,while content of GAs showed highly notable positive relevance to active grain filling period.