Effect Of Fertilizer Reduction On Cotton Yield Physiology And Nutrient Utilization Efficiency In Southern Xinjiang

In order to explore the effects of chemical fertilizer reduction on cotton yield and nutrient use efficiency,xinluzhong 67 was used as the test material to carry out field experiments of base fertilizer reduction and topdressing reduction.Four treatments of base fertilizer reduction were set up:C1=900kg·hm^-2,C2=600 kg·hm^-2,C3=300 kg·hm^-2,C4=0 kg·hm^-2.Topdressing fertilizer reduction:D1=1560kg·hm^-2,D2=1140kg·hm^-2,D3=900 kg·hm^-2,D4=660 kg·hm^-2,D5=420 kg·hm^-2and D6=0 kg·hm^-2,the experimental results are as follows:（1）With the increase of basal fertilizer reduction,the plant height,leaf number and functional leaf SPAD value of cotton decreased gradually.Stem diameter,fruit branch number,leaf area index（LAI）,net photosynthetic rate（P_n）,stomatal conductance（G_s）,transpiration rate（T_r）,peroxidase（POD）,superoxide dismutase（SOD）and catalase（CAT）showed a trend of increasing at first and then decreasing,while intercellular CO₂concentration（C_i）decreased at first and then increased.Malondialdehyde（MDA）is increasing.C1 had the largest plant height,leaf number and SPAD value,while C2 had the largest stem diameter,internode number of main stem,fruit branch number and leaf area index（LAI）.Among the average photosynthetic indexes of leaves,the net photosynthetic rate（P_n）,stomatal conductance（G_s）,transpiration rate（T_r）,peroxidase（POD）,superoxide dismutase（SOD）and hydrooxidase（CAT）of C2 were the highest,while the intercellular CO2 concentration（Ci）and malondialdehyde（MDA）of C4 were the highest.With the increase of topdressing reduction amount,plant height,LAI,SPAD,Pn,Gs,Tr of functional leaves increased first and then decreased,stem diameter decreased first and then increased and then decreased,internode number,fruit branch number,POD,SOD,CAT of main stem decreased gradually,Ci decreased first and then increased,MDA increased gradually,among which,plant height and stem diameter of D5 were the largest.The number of leaves,LAI and SPAD in D3 was the largest,and the number of internodes and fruit branches in D1 was the largest.Among the average photosynthetic indexes of leaves,POD,SOD and CAT of D1 were the largest,Pn,Gs and Tr of D2 were the largest,Ci and MDA of D6 were the largest.（2）Dry matter of stem,dry matter of reproductive organs,allocation coefficient of reproductive organs,theoretical maximum dry matter accumulation（C）,theoretical rapid dry matter accumulation（G_t）,boll number per plant and seed cotton yield decreased with the increase of basal fertilizer reduction.Leaves,leaf distribution coefficient,maximum accumulation rate of dry matter in time（tm）,rapid accumulation of termination time（t2）,rapid accumulation duration（△_t）,the maximum accumulation rate（V_m）,rapid accumulation of time（t1）,reduced number increased after the first harvest,the distribution coefficient of cotton stalks,boll weight reduced increase first.C1 had the largest stem,dry weight and distribution coefficient of reproductive organs,theoretical maximum dry matter accumulation（C）and theoretical rapid accumulation（G_t）in aboveground.C2 had the longest appearance time of maximum accumulation rate（t_m）,the longest termination time of rapid accumulation（t₂）,and the longest duration of rapid accumulation（△t）.The dry matter and distribution coefficient,maximum accumulation rate（V_m）and emergence time of rapid accumulation（t₁）of C3 leaves were the largest,while the distribution coefficient of C4 stems was the largest.Among the yield components,C2 had the highest plant number(18.36×104 plants·hm^-2),C1 had the highest boll number,boll weight and seed cotton yield(7.92 plants·hm^-1,5.18 g and 7 360.36 kg·hm-²),respectively.Stem dry matter,leaf dry matter and reproductive organ dry matter decreased gradually with the increase of topdressing reduction.Cotton theory of distribution coefficient,aboveground dry matter in reproductive organ biggest accumulation（C）,the maximum accumulation rate（V_m）,rapid accumulation theory（G_t）,the maximum accumulation rate in time（t_m）,rapid accumulation of termination time（t₂）,rapid accumulation duration（△_t）,boll number per,single boll weight,seed cotton yield were reduced after increase first,The distribution coefficient of stem and leaf decreased first and then increased,the emergence time of cotton rapid accumulation（T₁）decreased first and then increased,and the number of harvested plants changed irregularly.Among them,D1 had the largest stem,leaf and reproductive organ dry matter,D2 had the largest stem allocation coefficient,D3 had the largest leaf allocation coefficient,and D3 had the longest occurrence time of maximum accumulation rate（T_m）,the longest termination time of rapid accumulation（T₂）,and the longest duration of rapid accumulation（△t）.D6 had the highest reproductive organ allocation coefficient and the occurrence time of rapid accumulation（t₁）,while D5 had the highest theoretical maximum dry matter accumulation（C）,maximum accumulation rate（V_m）and theoretical rapid accumulation（G_t）.Among the yield components,D4 had the highest plant number(18.35×104 plants·hm^-2),D3 had the highest boll number per plant(8.06 plants·hm^-1),boll weight（5.13 g）and seed cotton yield(7328.45 kg·hm^-2),respectively.（3）Total nitrogen,total phosphorus,total potassium,alkali-hydrolyzed nitrogen,available phosphorus,0-60 cm soil layer,0-20 cm soil layer and 40-60 cm soil layer all decreased with the reduction of base fertilizer application,while the content of available potassium in 20-40 cm soil layer increased first and then decreased,among which,total nitrogen,total phosphorus,total potassium,alkali-hydrolyzed nitrogen and available phosphorus in each layer of C1 was the largest.The content of available potassium in 0-20 cm and 40-60 cm soil layer of C1 was the largest,while that in 20-40 cm soil layer of C2 was the largest.Total nitrogen,total phosphorus,total potassium,alkali-hydrolyzable nitrogen,available phosphorus,0-20 cm soil layer and 40-60 cm soil layer all decreased with topdressing reduction,while the available potassium content in 20-40 cm soil layer increased first and then decreased,and the contents of total nitrogen,total phosphorus,total potassium,alkali-hydrolyzable nitrogen and available phosphorus in D1 soil layer were the largest.The content of available potassium in 0-20 cm and 40-60 cm soil layer of D1 was the largest,while the content of available potassium in 20-40 cm soil layer of D3 was the largest.（4）N accumulation in stem,leaf and reproductive organs,P accumulation in stem and leaf of cotton,K accumulation in stem and reproductive organs,n use efficiency,P use efficiency,P partial productivity,K use efficiency and k partial productivity all decreased with the increase of basal fertilizer reduction.Reproductive organ phosphorus accumulation quantity,leaf potassium accumulation amount,nitrogen partial productivity,nitrogen agronomic efficiency,phosphorus agronomic efficiency,potassium agronomy efficiency enhancement,after the first one of C1 stem,leaf nitrogen accumulation amount,reproductive organs,stem,leaf phosphorus cumulants,stem,reproductive organs potassium accumulation amount is the largest,the reproductive organs of the C3 phosphorus accumulation quantity,C2 cotton leaf potassium cumulant is the largest,35.00 kg·hm^-2.In terms of nutrient use efficiency,C1 had the largest n use efficiency,P use efficiency,P partial productivity,K use efficiency and K partial productivity,reaching21.00%,16.43%,18.33 kg·kg^-1,7.75%,55.26 kg·kg^-1.The maximum nitrogen partial productivity,nitrogen agronomic efficiency,phosphorus agronomic efficiency and potassium agronomic efficiency of C2 were11.71 kg·kg^-1,2.43 kg·kg^-1,3.02 kg·kg^-1and 9.68 kg·kg^-1.With the increase of amount of fertilizer applied reduction,cotton stalks,leaf nitrogen accumulation amount,cotton stalks,reproductive organ phosphorus cumulants,cotton stalks,reproductive organs potassium accumulation amount,phosphorus fertilizer use efficiency were reduced gradually,reproductive organs nitrogen accumulation amount,leaf phosphorus cumulants,leaf potassium accumulation amount,nitrogen agronomic efficiency,k phosphorus efficiency of agriculture,agriculture efficiency,k use efficiency enhancement,after the first Partial productivity partial productivity of nitrogenous fertilizer,phosphate fertilizer,potash fertilizer partial productivity increases gradually,the stem and leaf nitrogen accumulation amount,D1 cumulants,leaf stalks and reproductive organ phosphorus potassium cumulants,stalks and reproductive organs cumulant,the biggest deal with D2reproductive organs nitrogen accumulation quantity of cotton,cotton leaf potassium accumulation of D3quantity biggest;In terms of nutrient utilization efficiency,the phosphorus utilization efficiency of D1 was the highest,reaching 2.55%.The agricultural efficiency of NITROGEN,phosphorus and potassium in D3was the highest,reaching 1.03 kg·kg^-1,4.32 kg·kg^-1and 7.96 kg·kg^-1,respectively.The n use efficiency of D2 was the highest,reaching 12.52%.The utilization efficiency of potassium fertilizer under D4 reached6.03%.D5 had the highest nitrogen,phosphorus and potassium partial productivity,reaching 13.10 kg·hm^-2,43.89 kg·hm^-2and 61.96 kg·hm^-2,respectively.