Effects Of Regulated Deficit Irrigation On Seed Maize

Crop Regulated Deficit Irrigation(RDI) is one of water saving irrigationtechnology which base on crop s physiological and biochemical reflection to waterdeficit．RDI can increase crop yield, and decrease water consumption, and raise theWUE. RDI have great future in the arid and semiarid area. If RDI was widely used inHeihe basin, it will biring great economic and social benefit. The experiment wasconducted at Linze station in2011, using corn hybrid No.92(Origin Agritech Limited)as materials. in seedling stage, jointing stage booting, maturation, According to soilwater suction, three moisture gradients were set in stage of seedling, jointing, bootingand maturation, and the three moisture gradients respectively were200kPa(moderate),400kPa (mild) and800kPa (medium). By researching the influence ofdifferent irrigation amount on plant growth, yield, quality, water use efficiency,photosynthetic characteristics in different growth stages of corn hybrid, the studyaimed to determine suitable deficit irrigation period and degree of corn hybrid inmiddle Heihe basin and discusses Productivity formation mechanism under thecondition of regulated deficit irrigation. Finally, the study provided the theory basisfor cultivation mode and technology research and development of corn hybrid toenhance water using efficiency. The main results are as follows:(1)The soil moisture content was high at first, and it was about13.2%at the endof seedling stage, in the range of experiment. And At the end of the handle of theseedling stage soil water content was; the soil moisture content in each treatment ofother stages was in the range of experiment as well.(2)Water deficit significantly reduced plant height of corn in the stage of seedlingand jointing, and the greater the degree of water deficit became, the greater the effectwas. What’s more, the effect in jointing stage was greater. The plant that was treatedby mild water deficit in seedling stage showed remarkable compensatory growth inplant height after rewatering, but the plant that was treated by medium deficit didn’t.In addition, water deficit in booting and maturation stage had no significant effect onplant height of corn. The influence of deficit irrigation on maize stem diameter was as similar as onplant height. From start to maturation, plant that was treated by mild and mediumdeficit in seedling stage had no significant influence with CK, whose stem diametershowed certain compensatory growth. The stem diameter of plant treated by mild andmedium deficit in jointing stage was remarkably thinner than other processing. Waterdeficit in booting and maturation stage had no significant effect on stem diameter.Root cap ratio in seedling was the largest, meaning that seedling was animportant period for development of maize root and water deficit treatment inseedling stage was beneficial to stimulate growth of roots. Root cap ratio of plant thatwas treated by water deficit in seedling stage was significantly bigger than that of CK.Except seedling stage, root cap ratio between other stages and treatments had nosignificant differences.At the end of seedling, leaf area of plant with medium water deficit treatmentwas significantly smaller than others. But at the end of jointing, it showed obviouscompensation effect and there was no difference between it and CK. leaf area of plantwith treatment T3and T4was significantly smaller than that of CK. Jointing stagewas the a key period of vegetative growth of corn, when plant displayed strongervitality after rewatering as a result of water deficit in seedling stage. Besides, waterdeficit in booting and maturation stage had no notable effect on leaf area.At the end of the seedling and in stage of jointing and booting, dry matteraccumulation was significantly lower than that of CK. And dry matter accumulationtreated with mild water deficit achieved its maximum, which had no difference withthat of CK and showed certain compensation effect.(3)Water deficit in seedling significantly reduced leaf net photosynthetic rate(Pn), stomata conductance (Gs) and transpiration rate (Tr), and the more water deficitwas, the bigger the range of reduction was. While mild water deficit treatment couldimprove the photosynthesis instantaneous water used efficient (WUE) of maize leaf.Pn, Gs and Tr of maize leaf were remarkably lower than that of CK, while WUE ofmaize leaf with mild water deficit treatment was obviously higher than that of CK.WUE of maize leaf with medium water deficit treatment in jointing and booting stage had no notable difference with that of CK, but WUE of maize leaf with medium waterdeficit treatment in maturation stage was significantly lower than that of CK.(4)The influence of RDI treatment in seedling stage on yield of corn hybrid hadno significant difference with CK, and irrigative water used efficient (IWUE) had nosignificant difference too. Corn hybrid with treatment of mild water deficit in jointingstage showed strong compensative growth later, whose yield had no difference withthat of CK. Therefore, it obviously enhanced IWUE. In addition, the aging of leafwith RDI in jointing stage slowed down in later growth stage, providing seed withmore assimilation products. RDI treatment in stage of booting and maturationremarkably reduced the yield of corn hybrid, and IWUE significantly reduced at thesame time.(5)The study showed that the moderate stage of RDI was jointing in middleHeihe basin, and the moderate extent was mild water deficit treatment(soil moisturesuction,400kPa).