The Effect Of Sowing Date And Density On Physiological Characteristics,Yield And Quality Of Oil Sunflower

Suitable sowing date can adjust light and temperature factors,improve crop environmental conditions,and sui Table.planting density can effectively use light and temperature resources and regulate the relationship between individuals and populations.Therefore,the experiment will be effective combination of sowing date and density,digging yield traits,quality parameters to achieve the best sowing date and density cultivation combination.This study uses oil sunflower‘T562’as the test material,adopts a two-factor split zone design,and sets 5 sowing dates(April 25,May 2,May 9,May 16,May 23),4 densities(3.75×10~4,4.5×10~4,5.25×10~4,6×10~4plants/hm2)to explore the most sui Table.sowing period and planting density.The main findings are as follows:(1)The growth period of sunflower shortens with the delay of sowing time,and the main stage of shortening is sowing to budding stage,while flowering to maturity stage is less affected by sowing time.The effective accumulated temperature(≥5℃)at the stage from budding to flowering increased with the delay of sowing date,and decreased gradually from flowering to budding.The utilization ratio of GDDs and accumulated temperature in the whole growth period was the best in T2 sowing period.(2)The average leaf area index(LAI)at the budding stage of sunflower was better than that at the early stage,and it was better at the early stage than that at the late stage,and increased with the increase of planting density.Too Early and too late sowing will make Pn,Tr,Gs decreased,Pn,Tr,Gs with the increase in density first increased and then decreased.(3)There was a higher correlation between GDDs and aboveground dry matter mass of sunflower,which increased gradually with the increase of GDDs,and the maximum dry matter was at T2 sowing time,and the dry matter mass increased first and then decreased with the increase of density.Sowing date and density had a great effect on dry matter distribution in vegetative organs,but the total proportion was constant.(4)The content of soluble sugar and nitrate reductase of sunflower in bud stage and flowering stage fit well with the equation of effective accumulated temperature of sunflower growth stage,and there is a great correlation.With the delay of sowing date,the content of nitrate reductase gradually decreased,and the content of soluble sugar gradually increased.Under density treatment,the contents of soluble sugar and nitrate reductase increased at first and then decreased with the increase of density.(5)Palmitic acid,stearic acid,oleic acid,linoleic acid and vitamin E in sunflower fruit were affected by sowing date,and stearic acid and vitamin E were affected by density.The content of fat decreased with the delay of sowing date.Under density treatment,the contents of fat,linoleic acid,palmitic acid and vitamin E were better than those of low density treatment,while the contents of oleic acid and stearic acid were better than those of high density treatment.(6)The kernel rate of sunflower was greatly influenced by sowing date,but the seed weight and yield of sunflower were less affected by sowing date.The results showed that the change of planting density could improve the yield more than sowing date.The highest yield of sunflower seed was 6859 kg/ha under the treatment of 60000 plants/ha at T2sowing date,while the best combination of quality and yield was 52500 plants/ha at T2sowing date.