Effects Of Sowing Density On Yield And Quality In "Tongmai 6" Wheat Variety

The improvement of wheat yield and quality in arid land largely depends on high quality varieties and its cultivation techniques."Tongmai 6" is a new winter wheat variety with high quality and suitable for planting in the dry land area.In order to master the characteristics of its growth and development in dryland and explore the supporting cultivation techniques for its production in dryland,so as to ensure that its genetic advantages can be fully played in the process of popularization,its population structure,individual agronomic traits,dry matter transport characteristics,grain-filling characteristics,lodging resistance,yield and quality of "Tongmai 6" wheat were systematically studied with planting density in 1.50×10~6plants /hm~2 to 4.50×10~6plants /hm~2 in the Yongshou Dry-farming Agricultural Experimental Station of Northwest A&F University from 2018 to2020.The results showed that:(1)Density has a significant effect on individual agronomic traits of wheat.With the increase of density,the plant height increased by 4.50-6.06cm;Secondary rooting,leaf age,first tillers and second tillers decreased by 2.65-3.80,0.01-0.93,1.20-1.25 and 1.80-2.10 respectively during wintering stage and booting stage.With the increase of density,ear bearing tiller percentage decreased by 9.89%,and the number of ear formation increased by2.09×10~6 plants /hm~2.From anthesis stage to maturity stage,the center of gravity of plants moved up-1.3-4.52 cm,internode wall thickness decreased 0.04-0.22 mm,and internode length increased 0.16-3.04 cm,but the difference was not significant.The mechanical strength of basal internode was reduced by 15.04-56.50 Kpa,the lodging resistance index of main stem of wheat was reduced by 0.33-1.18,and the lodging resistance of plant was reduced,no lodging occurred at high density.(2)The increase of density significantly reduced the dry matter accumulation per plant.The redistribution and transfer amount of dry matter stored in vegetative organs before flowering decreased from 1.38g/ plant to 0.36g/ plant,and the dry matter transport efficiency and the contribution rate of dry matter transport to the grain were the highest when the density was 3.30×10~6 plants /hm~2.The peak value of dry matter accumulation ranged from 3.30×10~6 plants /hm~2 to 3.60×10~6 plants /hm~2,with a pre-peak increment of2448.39kg/hm~2 and a post-peak decrease of 1099.31kg/hm~2.At the same time,with the increase of density,the dry matter percentage of panicle decreased by 2.26%-10.54%,the dry matter percentage of leaf and stem + leaf sheath increased by 2.26%-10.54%at the grain filling stage.The period of dry matter accumulation was the fastest from 12 d to 32 d after flowering,and the 1000-grain weight increment was 1.61g/d.The maximum grain-filling rate was delayed by 1.39 d,the rate decreased by 0.09mg/d,the average grain-filling rate decreased by 0.11mg/d,and the effective grain-filling time increased by1.18 d.(3)When the density of wheat increased from 1.50×10~6 plants /hm~2 to 3.30×10~6 plants/hm~2,the yield improved 110~6.70kg/hm~2 and growth rate was 18.12%,while a further increase in the density would decrease the yield.With the increase of density,the number of spikelets decreased by 4.80,the 1000-grain weight decreased by 0.79 g,the number of spikelets decreased by 0.79,and the number of sterile spikelets increased by 1.42.Through optimization,the highest yield was obtained under the planting densities of 3.41×10~6 plants/hm~2 and 3.63×10~6 plants /hm~2,respectively in two years.(4)Density had little effect on the quality of wheat,and only the stability time was significantly different between treatments,which could be prolonged by 1.15 min at most.The maximum drag resistance was 282.35 E.U at 1.50×10~6 plants /hm~2;The grain test weight,protein content,wet gluten content,sedimentation value,stability time and water absorb rate were all higher in the density range of 3.30×10~6 plants /hm~2 to 3.90×10~6 plants/hm~2.(5)Therefore,wheat "Tongmai 6" can obtain higher yield and better quality in the density range of 3.30×10~6 plants /hm~2 to 3.90×10~6 plants /hm~2.