Effect Of Delaying Irrigation In Jointing Stage On Creep Properties And Lodging Resistance Of Winter Wheat Under Different Planting Pattern

In order to study the effects on lodging resistance of winter wheat under the different precision planting pattern with delaying irrigation 10 day in jointing stage.The lodging resistance and creep under different loads of winter wheat stalks in different growth stages were studied based on different planting pattern and irrigation time in jointing stage,provide theoretical basis and technical support for water saving and high yield of winter wheat in Huang Huai Hai Plain.The study area was located at the water pool of Agronomy Experimental Station of Shandong Agricultural University(36°10′19″N,117°09′03″E)during the winter wheat growing seasons of 2016-2017 and 2017-2018.Taking "Ji mai 22" as the research material,the two planting patterns applied were wide precision planting pattern(W)and conventional cultivation planting pattern(C).For each planting pattern,the winter wheat was irrigated with 60 mm in the jointing stage(I1)and delaying irrigation 60 mm for 10 day in the jointing stage(I2),with total 4 treatments.The main physical parameters,stalk physical strength,creep properties of stem,lodging resistance index and grain yield of winter wheat was observed and analyzed,and the planting pattern and irrigation system of comprehensive optimization of lodging resistance and yield of winter wheat were studied.The results were as follows:(1)The planting pattern and delaying irrigation 10 day in jointing stage had no significant effect on plant height and gravity center height.Plant height and center of gravity height can not be directly used as the basis for judging the lodging resistance of wheat.The wide precision planting pattern decreased the fresh density of stem at heading stage,but had no significant effect on other stem characters.At the same time,delaying irrigation 10 day in jointing stage reduced the outer diameter of basic secondary internodes of winter wheat.Delaying irrigation in jointing stage can regulate internode character of stem of winter wheat in wide precision planting pattern,regulate stem quality,and avoid o vergrowth in the early stage of plant growth.Thus,the lodging resistance will be affected to some extent.(2)The growth environment significantly affected the stem mechanical properties of winter wheat,the mechanical characteristics of the stalks in filling stage was complicated.Delaying irrigation 10 day in jointing stage can effectively regulate the bending resistance of winter wheat,the wide precision planting pattern with delaying irrigation 10 day in jointing stage can improve the bending resistance of winter wheat at heading stage and reduce the ending resistance of winter wheat stems at dough stage.The conventional cultivation planting pattern with delaying irrigation 10 day in jointing stage reduce the ending resistance of winter wheat stems.The wide precision planting pattern reduced the elastic modulus of stem at heading stage and wax ripening stage,delaying irrigation 10 day in jointing stage increased the elastic modulus of stem at heading stage and dough stage.(3)The creep characteristics of winter wheat stem are obvious,and the creep process consists of three stages: initial stage,stable stage and accelerated stage.In the initial stage of creep,the duration of creep is shorter,the strain rate was faster,the creep stability stage tends to be stable,the variation of strain variable was small,with the passage of time,over to the creep acceleration stage,the strain variable increases rapidly and the stem was destroyed.It shows obvious aging characteristics.The stronger the growth period,the stronger the resistance of the stem to deformation,the larger the stretching displacement of the stem when resisting the external force,the lower water content of the stem in the later stage of the bearing,the variable is reduced,when the load is large enough,the stem rapidly transitions from the initial stage of the creep to the creep accelerating stage,and the stem structure is damaged.The entire process duration is short.(4)The calculation formula of lodging wind speed was derived,and the resistance to lodging of wheat was evaluated by using more intuitive wind speed.Delaying irrigation 10 day in jointing stage increased lodging resistance index at heading stage,decreased lodging resistance index at filling stage and dough stage,and significantly increased grain yield.The lodging resistance ability of wide precision planting pattern with delaying irrigation 10 day in jointing stage was better than that of conventional cultivation planting pattern with delaying irrigation 10 day in jointing stage.The lodging resistance in irrigation in jointing stage under conventional cultivation planting pattern was the best,followed by delaying irrigation 10 day in jointing stage under wide-precision planting pattern.The grain yield of winter wheat was significantly increased under the wide-precision planting pattern compared with conventionalcultivation planting pattern.Delaying irrigation 10 day in jointing stage could further increase the grain yield of winter wheat under the wide-precision planting pattern.Considering lodging resistance and yield factors,delaying irrigation 10 day in jointing stage under wide-precision planting pattern is the best combination to realize the stem lodging resistance and high grain yield of winter wheat.