Effects Of Soil Moisture And Planting Density On Tiller Occurrence And Spike Formation And Yield Of Wheat

In order to clarify the effect of planting density on tiller occurrence and spike formation of wheat under the condition of water saving and high yield,and the physiological mechanism of single spike yield and formation of different stems and tillers,the experiment was carried out in wenyangtian modern agricultural industrial park of Shandong Agricultural University in Tai’an City,Shandong Province from 2020 to 2021.The split area design was adopted.The main area was soil moisture and the sub area was planting density.The two soil water treatments were W70（the relative soil water content of 0～40cm soil layer was supplemented to 70%at jointing stage and flowering stage）and W0（no irrigation in the whole growth period）.Three planting densities were M1(1.8 million plants·hm^-2),M2(2.7 million plants·hm^-2)and M3(3.6 million plants·hm^-2),a total of 6 treatments,and each treatment was repeated for 3 times.The photosynthetic and senescence characteristics of different tillers,stems and tillers and their effects on grain yield were studied.The results are as follows:1 Effects of soil moisture and planting density on different tillering and spike formation of wheatUnder the condition of W70,the content of trans zeatin and the ratio of trans zeatin/abscisic acid,the area of tiller node,the net photosynthetic rate,transpiration rate and stomatal conductance of the uppermost expanded leaves of the main stem decreased with the increase of density;The number ofⅢandⅠP tillers per plant in overwintering stage,Ⅰ_P,Ⅳand other tillers in jointing stage decreased with the increase of density.The total number of stems and tillers per plant M1 was the highest,M2 was the second,and M3 was the lowest.At jointing stage,the net photosynthetic rate,transpiration rate,stomatal conductance and relative chlorophyll content of the uppermost expanded leaves of the main stem,I and II tillers decreased with the increase of density.The distribution of M1¹³C assimilates in the main stem and I tillers was higher,the number of spikes per plant was 1.1 and 2.9 higher than M2 and M3 respectively,and the number of spikes per hectare M2 and M3 were significantly higher than M1.Under the condition of W0,the distribution of M1¹³C assimilates in the main stem and tiller I was higher.The number of spikes per plant in M1 was 0.6 and 0.8 higher than that in M2 and M3,respectively.The number of spikes per hectare increased with the increase of density,with M3 being the highest,M2 being the second and M1 being the lowest.Under each planting density,the number of spikes per plant,total tillers and spikes per hectare of W70 were significantly higher than those of W0 treatment.2 Effects of soil moisture and planting density on yield per spike of different stems and tillers of wheat and its physiological basisUnder the condition of W70,the relative chlorophyll content,net photosynthetic rate,soluble protein content,superoxide dismutase activity,sucrose phosphate synthase activity and sucrose content of flag leaves after flowering of M1 main stem were not significantly different from those of M2,but significantly higher than those of M3;TillersⅠandⅡwere significantly higher than those of M2 and M3.The grain yield per plant of M1 was 33.5%and85.4%higher than that of M2 and M3,respectively.Under the condition of W0,the grain yield per plant of M1 was 43.6%and 88.2%higher than that of M2 and M3,respectively.The number of grains per spike,grain weight per spike and grain yield per plant of W70 were significantly higher than those of W0 treatment.3 Effects of soil moisture and planting density on grain yield and water use efficiency of wheatUnder the condition of W70,the grain yield per hectare of M2 was the highest,increased by 11.8%and 3.6%respectively compared with M1 and M3,and the water use efficiency was higher than that of M1 and M3,increased by 11.8%and 3.6%respectively.Under the condition of W0,the grain yield increased with the increase of planting density.The hectare grain yield of M3 increased by 6.6%and 1.5%respectively compared with M1 and M2,and the water use efficiency of M2 increased by 1.5%and 8.5%respectively compared with M1and M3.Under each planting density,the grain yield and water use efficiency of W70 per hectare were higher than those of W0 treatment.Under the condition of W70,the planting density of2.7 million plants·hm^-2（M2）has the highest grain yield and water use efficiency,which is the best treatment under the condition of water-saving and high-yield cultivation in this experiment.