Effects Of Potassium Supply On Chlorophyll Fluorescence Traits And Metabolism Of Carbon And Nitrogen Under Low Light Stress On Winter Wheat

The effects of growth light condition and potassium supply onwinter wheat chlorophyll fluorescence trait and metabolism of carbon and nitrogenwere studied in this paper. Using potassium fertilizer and shading of5×3fullybalanced scheme.Five K fertilizer rates were used:0,60,120,180,300kg/ha. Threeshading treatments were designed: NS（no shading）, SE（shading at early filling stage,from1day after anthesis to10days after anthesis） and SL（shading at later fillingstage, from15days after anthesis to25days after anthesis）. The shading environmentwas created by using black polypropylene fabric with30%light penetration. Eachtreatment had three replicates.1. In no shading condition, the suitable application amount of potassium fertilizer（K₂） can significantly increase the winter wheat leaf chlorophyll SPAD, chlorophyllfluorescence parameters qP and ETR, significantly reduced the chlorophyllfluorescence parameters F0and qN, which can increase the winter wheat leafphotosynthesis rate and light use efficiency, so as to improve nutrient absorption,accumulation and transfer finally, to improve the yield of winter. Compared with noshading, chlorophyll SPAD, qP and ETR during grain filling stage of winter wheatwere decreased, F0and qN increased under shading. While the early filling stageshading condition, high potassium fertilizer （K₃, K₄） could significantly increase thewinter wheat leaf chlorophyll SPAD, chlorophyll fluorescence parameters qP andETR, significantly reduced the chlorophyll fluorescence parameters F0and qN, butdue to the shading conditions have a negative effect on the chlorophyll fluorescenceparameters, resulting in filling stage shading condition potassium fertilizer treatmentsof winter wheat yield increased, but still significantly lower than those of shading. Inlater filling stage shading condition, high potassium fertilizer （K₃, K₄） cansignificantly improve wheat leaf chlorophyll SPAD, chlorophyll fluorescenceparameters qP and ETR, significantly reduced the chlorophyll fluorescenceparameters F0and qN, but because the winter wheat grouting process is finished, thechlorophyll fluorescence parameters change effects on yield is not obviously, and tend to be the same with no shading condition.2. The shading environment could significantly decrease the stem and sheath offructan and soluble sugar content, but the degree at shading early stage effect on stemand sheath of fructan and the content of soluble sugar is more serious than in lateshading condition. Different seed developmental stages of shading, total sugar contentin grain soluble but was significantly higher than that of in shading condition, theshading treatment is not shading reduced the soluble sugar content of seed treatment,but may improve relevant dilution and yield of soluble sugar. The suitable applicationamount of potassium fertilizer no shading condition （K₂） is conducive to theaccumulation of grain-filling stage of winter wheat stem, sheath content of fructan andcontent of soluble sugar, and later stage of decomposition and output. The relativelyhigh potassium fertilizer （K₃, K₄） was needed to reduce the ease of stem sheathsoluble carbohydrate in shading conditions. High potassium has an importantsignificance in improving grain weight and yield, because it can improve thetransformation of stem and sheath of winter wheat fructan and soluble sugar to grainstarch shading condition, the grain filling rate of Winter Wheat. But due to thegrouting process is near the end in the late grain filling stage shading conditions, thechanges in stem and sheath of winter wheat fructan, soluble sugar content effect onyield is not obvious, and the yield in late filling stage shading condition have a sameperformance with no shading condition.3. The suitable of potassium fertilizer （K₂） was in favor of vegetative organs ofwinter wheat dry matter accumulation and transfer no shading condition, higher orlower potassium fertilizer is not conducive to dry matter accumulation and transfer inwinter wheat. Different shading stage can reduce the leaf, stem, sheath and panicledry matter accumulation of winter wheat, led to the proportion of dry matterdistribution in different organs changed, assigned to the stem, leaf and sheathincreased in proportion, and assigned to the ear to reduce the proportion of dry matter;the proportion of organs nutrition Institute increase, but reduced the proportion ofgrain dry matter. High potassium fertilizer （K₄） not conducive to improved thenutritive organ dry matter accumulation, but conducive to improve vegetative organsdry matter transfer. At the late shading stage, the effects on dry matter accumulationand translocation tends to not shading treatment consistent on winter wheat.4. Shading at different grain filling stage induced the increase of nitrogen contentin vegetative organs of winter wheat, but because a significant decrease of dry matter in shading condition, the nitrogen accumulation decrease. Compared with no shadingcondition, the vegetative organs transfer of nitrogen had significant improved shadingat early stage, but it was contrary at later shading stage. High potassium fertilizer （K₄）condition was not conducive to vegetative organs nitrogen accumulation on winterwheat at early shading stage, but in favor of nutrition organ nitrogen transferring tokernel, the nitrogen accumulation and transfer in K₂treatment was highest shading atlater filling stage. High potassium fertilizer is beneficial to improve the yield of winterwheat at shading in filling stage, while the lower amount of potash fertilizer isbeneficial to improve the yield of winter wheat.5. The high or lower potassium fertilize can decreased the thousand seed weightand grain yield of winter wheat in no shading condition, the suitable applicationamount of potassium fertilizer （K₂） can significantly improve the thousand seedweight and grain yield of winter wheat. The grain was rapid growth in the early stageof grain filling, so shading at this stage can signally effect the grain yield, therelatively high amount of potash fertilizer （K₃, K₄） can improve the yield andthousand seed weight of wheat grain. The grain filling is basically completed duringlate filling period, so shading at this stage had a less affected on yield of winter wheat,and the rules of performance tends to the same as shading condition.