Respones Of Yield And Physiological Index Of Introduced Maize Varieties To Planting Density Based On Tibett Plateau

This experiment used corn varieties Xianyu 335,Zhengdan 958,and MC278 planted at the internship base of the School of Plant Science at Tibet Agriculture and Animal Husbandry University in 2022 as test materials.Six planting density gradients were set,with 45000 plants/hm ~2、 60000 plants/hm~2、 75000 plants/hm ~2、 90000 plants/hm ~2、 105000 plants/hm ~2、 135000plants/hm ~2,To study the effects of different planting density treatments on the growth,development,and yield of maize in the Nyingchi region of Tibet,in order to determine the suitable planting density for maize in the Nyingchi region of Tibet,and provide theoretical basis and practical reference for maize production in the Tibetan Plateau.The main test results are as follows:1.Planting density has a significant impact on the agronomic traits of maize.The planting density of corn is significantly positively correlated with its plant height,ear height,and root length,increasing with the increase of density.However,the stem thickness and root weight of the third node at the base,as well as the root plant spacing width,decrease with the increase of density.There is a significant difference in planting density between corn and the three.As the growth period of corn progresses,the leaf area per plant of corn shows a trend of first increasing and then decreasing under different planting densities,and the leaf area per plant of different varieties reaches its peak during the filling period.The accumulation of dry matter per plant conforms to the generally recognized and fundamental laws of cooperative biology.As the planting density continues to increase,the accumulation of dry matter per plant continues to decrease.Improving the dry matter accumulation of leaves,leaf sheaths,stems,and bracts before the silking stage of corn can effectively improve its grain yield.2.Planting density has a significant impact on the photosynthetic characteristics of maize.The chlorophyll content of Zhengdan958 and MC278 decreased with the increase of density,basically keeping consistent with the changing trend of photosynthetic rate,transpiration rate,stomatal conductance,intercellular carbon dioxide concentration,and dry matter accumulation,while the chlorophyll content of Xianyu335 decreased first and then increased with the increase of density.It can be seen that with the increase in density,the decrease in individual plant is mainly compensated for by increasing the population photosynthetic rate,thereby ensuring the total dry matter accumulation of the population,and ultimately affecting the formation of corn population yield.3.Planting density has a significant impact on physiological characteristics of maize.With the increase of planting density,the levels of malondialdehyde(MDA),superoxide dismutase(SOD),catalase(CAT),and peroxidase(POD)varied among the three varieties,but the overall trend was consistent.Malondialdehyde(MDA),catalase(CAT),and peroxidase(POD)all increased with the increase of planting density,while superoxide dismutase(SOD)decreased with the increase of planting density.4.Planting density has a significant impact on maize yield and yield correlation.The performance of different maize varieties under the same planting density is also inconsistent,but the yield of the three maize varieties shows a trend of first increasing and then decreasing with the increase of planting density,with Zhengdan958 and MC278 at 75000 plants/hm~2 The peak is reached at,while Xianyu335 is at 60000 plants/hm~2 Reaching a peak value at;Among the yield components,planting density has a significant impact on ear and grain traits and economic yield of maize.Increasing planting density is the basic condition for achieving high yield of maize in the Nyingchi region of Tibet.Zhengdan958 and MC278 have a yield of 75000 plants/hm~2-90000 plants/hm~2 The performance of Xianyu335 is good,while that of Xianyu335 is 45000 plants/hm~2-60000 plants/hm~2 It is more suitable to plant the three varieties at a planting density greater than 90000plants/hm~2 "The rapid decline in yield and poor performance of ear traits and photosynthetic characteristics are not suitable for planting above this planting density.".Therefore,under suitable planting density,increasing leaf area index,increasing dry matter accumulation,and enhancing protective enzyme activity are conducive to achieving high yield.