Effects Of Different Irrigation Amount And Density On Growth Physiology And Yield Formation Of Membrane-free Cotton

In order to clarify the effects of irrigation amount and planting density on the growth index,photosynthetic characteristics and yield of cotton without mulch under drip irrigation,Taking"Zhong 619"as material,the field experiment of two factor split plot design was carried out,The main irrigation area is 3000 m³/hm²（W1）,4 500 m³/hm²（W2）and 6 000 m³/hm²（W3）;The density was 29.24×10⁴ plants/hm²（M1）,26.32×10⁴ plants/hm²（M2）,23.92×10⁴ plants/hm²（M3）and 21.93×10⁴ plants/hm²（M4）,The effects of different irrigation amount and density on the growth index,yield and yield of film free cotton were studied,Dry matter accumulation and photosynthetic physiological index,The spatial distribution of cotton bolls is closely related to the root distribution in the underground,The effects of antioxidant enzyme activity and yield components,etc,The conclusions are as follows:（1）The plant height of film free cotton increased rapidly from initial bud to full bloom,and finally decreased with the increase of density and increased with the increase of irrigation water.The plant height,stem diameter,leaf number,internode number and fruit branch number decreased with the increase of density,while the node position and height of the first fruit branch increased with the increase of density;There were significant differences in plant height,stem diameter,leaf number,internode number,fruit branch number,first node of fruit branch and height of first node among treatments,which were positively correlated with irrigation amount.The dynamic change of dry matter accumulation per plant of film free cotton showed a slow fast slow"s"curve.With the increase of density,the dry matter accumulation of each plant decreased gradually.From the distribution of dry matter in different organs,the difference of dry matter accumulation in vegetative organs of different density treatments was the largest.The dry matter accumulation of reproductive organs increased with the increase of density at bud stage,and M3 was the largest at flowering stage.The total biomass of W2M3 was the largest at boll opening stage,reaching 19297.53 kg/hm²,while that of w1m1 was the smallest at boll opening stage,reaching 12 873.20 kg/hm².（2）The highest LAI and photosynthetic function were observed in full flowering stage,With the increase of density and irrigation amount,LAI increased.The LAI of W2M3 treatment was stable,and higher in the later stage.The LAI of W3M1 treatment was the highest,but it decreased rapidly after full bloom.As the birth process goes on,The SPAD value of film free cotton increased first and then decreased,It reached the maximum in full bloom,And with the increase of density and irrigation amount,it first increases and then decreases.Suitable irrigation and reasonable density were beneficial to the improvement of photosynthetic function of leaves,The treatments W2M3,W2M4 and W3M3 had higher P_n,G_s and T_rand lower C_i at full flowering stage,The photosynthetic"nap"in diurnal variation was not obvious.The maximum values were 29.10～32.15μmol CO₂/（m²·s）,0.91～1.07 mol/（m²·s）,12.78～13.87 mmol H₂O/（m²·s）and 117.97～126.4μmol CO₂/（m²·s）,respectively.The yield also reached a high level of 4 948.25～5 721.67kg/hm².The LAI and photosynthetic index of W3M4 treatment were higher,But in the later stage,it decreased too fast,W1M1 was the lowest,The results showed that high or low irrigation and density were not conducive to the improvement of photosynthetic function of leaves;The effects of irrigation amount and density on leaf growth and photosynthetic index had interaction effect,The effect of density is higher than that of moisture.（3）With the development of cotton,the content of MDA in the leaves of film free cotton increased,and decreased first and then increased with the increase of density,The average value is M1>M2>M4>M3,The flocculent period was 45.09μmol/g FW～50.85μmol/g FW.The average value under different irrigation amount was W1>W2>W3,The opening period was 45.09μmol/g FW～48.75μmol/g FW The contents of POD,SOD and CAT in leaves of film free cotton increased at first and then decreased with the growth process,With the increase of density,M3 treatment was the highest,followed by M4 treatment,M2treatment was the second,and M1 treatment was the lowest,The results showed that W2>W3>W1 under different irrigation amount.（4）The root length density and surface area of non film cotton were 0～20 cm>20～40 cm>40～60 cm under W1 treatment,W2 treatment and W3 treatment showed 40～60 cm>20～40 cm>0～20 cm.With the increase of density,root length density and surface area were M3>M4>M2>M1.（5）With the increase of density or the decrease of irrigation amount,the bolls of lower fruit branch and inner ring increased,while the bolls of middle and upper fruit branch and outer ring decreased;Under the suitable irrigation amount（W2,W3）and planting density（M3,M4）,the yield of film free cotton was 4948.25～5 721.67 kg/hm²,At this time,the plant height was 67.3～76.4 cm,and the number of main stem internodes was 13.7～14.7,The distribution proportion of bolls was as follows:lower part:middle part:upper part=4.1～4.9:3.5～3.7:1.6～2.1,inner ring:outer ring=6.4～8.3:1.7～3.6.The results showed that the suitable irrigation amount and planting density were 4 500～6 000 m³/hm² and 21.93～24.62×10⁴plants/hm2,When irrigation amount was 4 735.93 m³/hm² and planting density was 24.59×10⁴ plants/hm²,the highest yield was 5471.48 kg/hm².