Effects Of Different Chemical Topping Agents And Topping Time On Yield And Quality Of Main Cotton Varieties In Alar Reclamation Area

In order to clarify the effects of chemical topping agent and topping time on the growth index,dry matter accumulation,yield and quality of popularized cotton varieties in Alar Reclamation Area,"Tahe No.2,Xinluzhong No.82 and Xinluzhong No.85" were selected as the test materials to carry out the field test of three factor split plot design.The varieties were the main area(f),which were Tahe No.2(represented by TF),Xinluzhong No.82(represented by XF)and Xinluzhong No.85(represented by NF);Different chemical topping agents are split zone(b),25% fluoroacetamide(represented by B1),98% ketamine +additives(represented by B2),meperidonium(represented by B3)and manual topping(represented by B4);Different topping time(s)are the factors of re cracking area,which are topping on July 5(expressed by S1)and July 14(expressed by S2).The effects of different chemical topping agents and topping time on agronomic traits,dry matter accumulation and Leaf SPAD,reproductive organ distribution,changes of ABA and CTK contents,yield and fiber quality components of cotton were studied.The conclusions are as follows:(1)The growth rate of plant height of the tested varieties decreased significantly after topping,and the final plant height was greatly affected by the topping time.The later the topping time,the greater the plant height.The varieties treated with S2 showed XF > TF > NF.Variety XF increased by 16.72 cm and 18.09%;TF increased by 10.01 cm and 12.57%;Variety NF increased by 3.74 cm and 4.07%;There was a negative correlation between the diameter of varieties and plant height.The higher the plant height,the lower the diameter;The growth rate of diameter from bud stage to boll opening stage under S1 treatment was significantly higher than that under S2 treatment.The diameter of varieties TF and XF S2 increased by0.45 mm and 0.84 mm compared with S1,and the diameter of variety TF decreased by 0.31 mm compared with S1 at S2 stage.(2)Variety TF was greatly affected by topping agent.There were significant differences in plant height,stem diameter,number of fruit branches,number of leaves,number of main stem internodes,height of the first fruit branch and topping agent.Topping time had significant differences in plant height and height of the first fruit branch,but had no significant differences in other characters;Under different topping treatments,there were no significant differences in plant height,stem diameter,number of leaves and main stem internodes,but there were significant differences in the height of the first fruit branch and the beginning of the fruit branch.Under different topping times,there was no significant difference in the height of the first fruit branch,and the differences in other measured characters were very significant;Under different topping agent treatments,the plant height,stem diameter and leaf number of variety NF reached significant differences,and the number of main stem internodes,the height of the first fruit branch and the number of fruit branches reached extremely significant differences.Under different topping time treatments,there was no significant difference in plant height,and the other measured characters reached extremely significant differences.(3)The dynamic change of dry matter accumulation from bud stage to boll opening stage of the tested varieties showed a fast slow fast "s" curve.The tested varieties were greatly affected by the topping time.The period with the highest weight of dry matter accumulation of all varieties in S1 period was boll opening stage,the period with the highest weight of TF and XF in S2 period was boll opening stage,and the period with the highest weight of NF was boll opening stage.Under S2 treatment,the weight of S2 treatment was 15.76 g higher than that under S1 treatment,with an increase of 15.68%;The total amount of dry matter accumulation per plant in boll opening stage was NF > XF > TF.Compared with TF and XF,NF increased by 23.46 g and 20.59 g,with an increase of 23.51% and 20.16%;The total dry matter of a single plant treated with different topping agents was B4 > B2 > B1 > B3.B4 increased by 2.43 g,2.09 g and2.81 g compared with B1,B2 and B3,with an increase of 2.25%,1.93% and 2.62%.In the combined treatment,the accumulation of dry matter per plant of nfb4s2 was the largest,138.1g.(4)The content of the tested varieties under the treatment of "S1" was generally higher than that under the treatment of "S2".Different chemical topping agents had no significant difference in the changes of ABA and CTK contents in the top four leaves of cotton,and the overall change trend of hormone dynamics was the same under the same topping time;Different topping time played a decisive role in the dynamic changes of ABA and CTK contents;However,chemical topping can significantly change the growth or decline rate of ABA and CTK content in cotton.(5)The yield of tested varieties was significantly different under different topping agents,and different topping time had little effect on cotton yield;Tahe No.2 had the effect of increasing yield when topping in S2 period,and B1 and B3 had the best effect of increasing yield,up to 7.57%;Xinluzhong 82 had the best effect of selecting B1 and B2 in S2 period,with an increase of 12.85%;Xinluzhong 82 had the best effect of selecting B1 and B2 in S2 period,with an increase of 7.28% and 8.83%.(6)The fiber quality of the tested varieties had no significant difference under different chemical topping agents and topping time;There were significant differences among the varieties themselves,and there were significant differences in marcolon value,short fiber and elongation of the tested varieties,but there were no significant differences in other measured characters.