Effects Of Bio Organic Fertilizer Partially Replacing Chemical Fertilizer On Growth Characteristics And Fertilizer Utilization Efficiency Of Film-free Cotton

In order to clarify the impact of partial substitution of bio organic fertilizer for chemical fertilizer on the growth index,nutrient utilization efficiency and yield composition of film-free cotton,the field experiment of two single factor random block groups of partial substitution of bio organic fertilizer for base fertilizer and partial substitution of bio organic fertilizer for topdressing fertilizer was carried out with’Zhong 619’as the test material,in which the substitution proportion of base fertilizer was 0%(expressed by A_CK),25%（expressed by A₁）,50%（expressed by A₂）,respectively 75%（represented by A₃）and 100%（represented by A₄）,and the top dressing substitution ratios are 0%(represented by B_CK),25%（represented by B₁）,50%（represented by B₂）,75%（represented by B₃）and 100%（represented by B₄）respectively.The effects of each treatment on the aboveground growth index,dry matter accumulation,soil nutrient content,plant nutrient utilization efficiency,fiber quality and yield components of film-free cotton are studied.The conclusions are as follows:（1）The plant height,stem diameter,total leaf number,internode number,fruit branch number,dry matter accumulation,Leaf SPAD value and population Lai of film-free cotton treated with base fertilizer substitution and topdressing substitution were significantly higher than those treated with chemical fertilizer alone.In the substitution of base fertilizer,the plant height of A2,the stem diameter and leaf number of A1,the dry matter accumulation per plant of A4,the Leaf SPAD value of A3 and the Lai of A4are the largest;In top dressing substitution,B4 plant height,B2 stem diameter and leaf,B2 dry matter accumulation per plant,B4 Lai and B3 Leaf SPAD value were the highest.It can be seen that organic fertilizer instead of chemical fertilizer can significantly promote the growth of film-free cotton,and the substitution rate of base fertilizer and topdressing is 50%～100%.（2）The nutrient content of each soil layer of film-free cotton was relatively high in bud stage and flowering and boll stage,and decreased in boll opening stage.The substitution of organic fertilizer and base fertilizer had a great impact on the nutrients in the middle and lower soil layers.Among them,the contents of total nitrogen,total phosphorus and available nutrients in A2 treatment 0～20cm soil layer were the highest;The content of total nitrogen in 20～40cm soil layer treated with A4,alkali hydrolyzable nitrogen in A3,total phosphorus in A1 and available phosphorus and potassium in ack were the highest;The contents of alkali hydrolyzable nitrogen,total nitrogen and total phosphorus in A4 treatment and available phosphorus and available potassium in ack treatment were the highest in 40～60cm soil layer;The results showed that the substitution of organic fertilizer for 75%～100%chemical fertilizer was beneficial to the accumulation of alkali hydrolyzable nitrogen and total nitrogen nutrients in each soil layer,and the substitution of available phosphorus and potassium was higher;The top dressing substitution of organic fertilizer had a great impact on the nutrients in the upper and middle soil layers.Among them,the contents of alkali hydrolyzable nitrogen and total phosphorus in 0～20cm soil layer of B4 treatment,available phosphorus in B1 treatment and available phosphorus and total nitrogen in BCK treatment were the highest;The content of alkali hydrolyzable nitrogen in 20～40cm soil layer of B2 treatment,the content of total phosphorus and available phosphorus and potassium in B1 treatment and the content of total nitrogen in BCK treatment were the highest;The contents of alkali hydrolyzable nitrogen,total nitrogen,available phosphorus and potassium in B1 treatment and total nitrogen in BCK treatment were the highest in 40～60cm soil layer of B2 treatment.It can be seen that the top dressing of organic fertilizer instead of chemical fertilizer not only reduces the total nitrogen of soil,but also increases other nutrients in varying degrees,and the increasing effect of B1 and B2 treatment is greater.（3）The accumulation of nitrogen,phosphorus and potassium in film-free cotton plants was the highest at boll opening stage.In the substitution of base fertilizer,the accumulation of nitrogen in A1 was the highest,and the accumulation of phosphorus and potassium in A3 was the highest;In top dressing substitution,the accumulation of nitrogen,phosphorus and potassium in B2 was the highest.In terms of nutrient use efficiency,the nitrogen use efficiency of plants in the substitution of base fertilizer was higher than that of phosphorus and potassium,and the phosphorus use efficiency of plants in the substitution of top dressing was higher than that of nitrogen and potassium;In terms of nutrient distribution rate,in the replacement of base fertilizer,the nitrogen distribution rate of leaves,stems and reproductive organs of ACK treatment,A1 treatment and A4 treatment was the largest,the phosphorus distribution rate of leaves,stems and reproductive organs of ACK treatment,A3 treatment was the largest,and the potassium distribution rate of leaves,stems and reproductive organs of A2 treatment,A4 treatment and A1 treatment was the largest;In topdressing substitution,the nitrogen distribution rate of leaves,stems and reproductive organs treated with B3,B4 and B1 was the largest,the phosphorus distribution rate of leaves,stems and reproductive organs treated with B4,B3 and B2 was the largest,and the potassium distribution rate of leaves,stems and reproductive organs treated with B3 and B2 was the largest.It can be seen that higher base fertilizer substitution and suitable topdressing substitution are conducive to the accumulation of phosphorus and potassium in phosphorus plants.Except for the nitrogen and phosphorus in leaves,the nutrient utilization rates of other organs were higher in organic fertilizer substitution treatment than in non substitution treatment.Among them,the distribution rates of nitrogen and potassium in reproductive organs replaced by 100%base fertilizer and phosphorus and potassium in stems and leaves replaced by 100%topdressing were the largest,indicating that increasing the proportion of base fertilizer substitution is conducive to the growth of buds and bolls,and increasing the proportion of topdressing substitution is conducive to the development of stems and leaves.（4）In the substitution of base fertilizer,the seed cotton yield,lint yield,number of harvested plants,number of bolls per plant and quality of bolls per plant of A3 treatment were higher than those of other treatments,reaching 6070.31kg/hm2,2474.04 kg/hm2,189400 plants/hm2 and 6.14 plants/plant respectively.The lint percentage of A4 treatment was the highest,which was 42.22%.In topdressing substitution,the seed cotton yield,lint yield,number of harvested plants,number of bolls per plant and quality of bolls per plant of B2 treatment were higher than those of other treatments,up to 6108.77 kg/hm2,2559.38 kg/hm2,183800 plants/hm2 and 6.03 plants/plant respectively.The lint percentage of B3treatment was the highest,which was 42.16%.（5）The quality analysis showed that the average length of the upper part of the fiber was the largest when the base fertilizer was replaced by 25%～75%,the fiber uniformity was the highest when the base fertilizer was replaced by 50%～100%,the fiber breaking strength was the best when the lower cotton boll was replaced by 25%,the middle and upper cotton boll was replaced by 100%,the elongation of the upper,middle and lower cotton boll was the best when A1,A2 and A4 were treated,and the micronaire value was the largest when ack was treated.In the top dressing substitution,the average length of the upper half of the fiber treated with B3 is the largest,the uniformity of the upper,middle and lower bolls is the highest in B3,B1 and BCK,the breaking specific strength is the largest in B4,B2 and B1,and the elongation is the largest in B1,BCK and B4,respectively;Makrolon value was the largest in B3 treatment.