| The experiments for different nitrogen rate of slow release fertilizer at different periods were conducted to investigate the nitrogen management on the plant type,maturing phase and physiological basis for direct seeding cotton after wheat harvest(DSCWH)at the cotton growth seasons of 2016 to 2017 in experimental farm of Yangzhou University.The main results were as follows:1.The effects of nitrogen management of slow release fertilizers on yield and its compositionThe results of the two years experiment showed that the yield of the slow release fertilizer treatments was higher than that of non fertilizer treatment(AO).Except for the yield of the 2nd leaf-age nitrogen level on 45kg.hm-2 treatments(A1B1)was lower than that of the conventional fertilizer treatment(CK),the yield of other slow release fertilizer treatments was significantly higher or little difference than that of the conventional fertilizer treatment.In 2016,the yield of the 4nd leaf-age nitrogen level on 90kg · hm-2 treatments(A2B2)increased 24.2%than that of the conventional fertilizer treatment(CK).In 2017,the yield of the 2nd and 4nd leaf-age nitrogen level on 90kg · hm-2 treatments(A2B1,A2B2)increased 14%and 9.7%than that of the conventional fertilizer treatment(CK).Under the same amount of nitrogen application,the yield of low medium high nitrogen treatments in the 4nd leaf-age in 2016 was 22.6%,14.8%and 15.7%significantly higher than that of the the 2nd leaf-age treatments.The yield of low medium high nitrogen treatments in the 2nd leaf-age was 5.3%,4%and 3%higher than that of the 4nd leaf-age treatments,but the difference was not significant.Under the same application,period of slow release fertilizer,the yield of nitrogen level on 90kg · hm-2 treatments was the highest,reaching 3764.1?4198.7kg · hm-2.Yield components showed that the high yield was the result of the combined effect of boll number and boll weight.2.The effects of nitrogen management of slow release fertilizer on plant typeSlow release fertilizer promoted the increase of plant type index compared with non fertilization(AO);Compared with conventional fertilization(CK),nitrogen level on 90kg·hm-2 in the the 4nd leaf-age was more beneficial to the plant type of centralized boll forming.Regression analysis showed that there was a extremely significant parabolical regression relationship between plant height,the number of fruit branches,the ratio of fruit node/fruit branches,length of fruit branch,internode length of main stem,fruit intemode length,intemode diameter of main stem,fruit internode diameter and the intensity of retained boll.The equation showed that the plant height was 80.7?90.5cm,the number of fruit branches was 11.6?12.2,the ratio of fruit node/fruit branches was 2.4?2.6,length of fruit branch was 15.6?19.2cm,internode length of main stem was 5.4'7.7cm,fruit internode length was 6.5cm,intemode diameter of main stem was 6.8mm,and fruit internode diameter was 3.0mm,and the intensity of retained boll was the highest.There was a significant or extremely significant positive correlation between fruit node,the angel between the leaf and horizontal plane and the intensity of retained boll.There was a extremely significant negative correlation between bending degree of fruit branches and the intensity of retained boll.Increasing the fruit nodes and decreasing the bending degree of fruit branches is beneficial to increase the intensity of retained boll.The nitrogen level of slow release fertilizer at 90kg ·hm-2 is conducive to establishing good plant type and achieving ceitralized boll forming.It laid the foundation for mechanical harvesting.3.The effects of nitrogen management of slow release fertilizer on maturing phaseCompared with no fertilization,slow release fertilizer slowed down the process of maturing phase of cotton plants.Compared with conventional fertilization,nitrogen level on 90kg·hm-2 in the 4nd leaf-age was more conducive to the formation of normal maturing phase.The regression analysis showed that there was extremely significant positive correlation between the ratio of yellow leaves/total leaves,the ratio of bolls/total leaves,the ratio of red-stem/total-stem for main stem,the ratio of red-stem/total-stem for four upper fruit branches in start boll opening stage(9/23)and boll-opening percentage in flourish boll opening stage(10/8).There was extremely significant negative correlation between boll opening countdown node in final boll opening stage(10/28)and final boll-opening percentage.There was extremely significant positive correlation between the rate of shed leaves in final boll opening stage(11/2)and final boll-opening percentage.There was extremely significant parabolical correlation between the ratio of yellow leaves/total leaves,the ratio of bolls/total leaves,the ratio of red-stem/total-stem for main stem,the ratio of red-stem/total-stem for four upper fruit branches in start boll opening stage(9/23)and the intensity of boll-opening.Therefore,the ratio of yellow leaves/total leaves was 14%,the ratio of bolls/total leaves was 0.36,the ratio of red-stem/total-stem for main stem was 45%,the ratio of red-stem/total-stem for four upper fruit branches was 29%-58%,which is beneficial to the inprove of the rate of the boll opening.Application,of suitable slow release fertilizer in the 4nd leaf-age can regulate the maturing phase of direct seeding cotton planted after wheat harvested,and lay the foundation for centralized boll-opening and mechanical harvesting.4.The effects of nitrogen management of slow release fertilizers on leaf carbon and nitrogen metabolism physiologyCompared with non fertilization,the management of slow release fertilizer could improve the chlorophyll content and fluorescence efficiency(Fv/Fm).of the whole growth period The application of slow release fertilizer in the 2nd leaf-age was beneficial to improve the chlorophyll content and fluorescence efficiency of cotton leaves in the early growth period(before 7/30).Application of slow release fertilizer in the 4nd leaf-age improve the chlorophyll content and fluorescence efficiency of cotton leaves at late growth stage period(after 8/30).Nitrogen content increased was beneficial to increase chlorophyll content,but slow release nitrogen level on 90kg·hm-2 was more conducive to keep higher photosynthetic efficiency in late growth period.The application of slow release fertilizer in the 2nd leaf-age was beneficial to increase carbohydrate metabolism in early growth period,soluble sugar,sucrose synthetase,sucrose phosphate synthetase and sucrose invertase was significantly higher than that of other solw release fertilizers and no fertilizer treatments,and increased with the increase of nitrogen application rate.The application of slow release fertilizer in the 4nd leaf-age was beneficial to the increase of carbon metabolism in the late gro,wth period,soluble sugar,sucrose synthetase,sucrose phosphate synthetase and sucrose invertase were significantly higher than that of the 2nd leaf-age and no fertilizer treatment,especially the effect of nitrogen level on 90kg · hm-2 was much better.The effect of slow release fertilizer on nitrogen metabolism was similar to that of carbon metabolism.The application of the 2nd leaf-age slow release fertilizer could improve the content of amino acid,soluble protein and GPT,GOT activity in early growth period(7/30).The application of the 4nd leaf-age slow release fertilizer improve the nitrogen metabolism intensity after August 30th.Because of the difference in nitrogen metabolism intensity between medium and high nitrogen treatments was no significant,slow release nitrogen level on 90kg · hm-2 can achieve low input and high efficiency.The correlation analysis showed that there was significant or extremely significant positive correlation between SPAD value,soluble sugar,soluble protein,amino acid content,sucrose synthetase,sucrose invertase,GPT,GOT activity and plant height,the number of fruit branches,fruit node,the ratio of fruit node/fruit branches,length of fruit branch.There was significant or extremely significant positive correlation between SPAD value,soluble sugar,soluble protein,amino acid content,sucrose synthetase,sucrose invertase and intemode length of main stem.There was significant or extremely significant positive correlation between SPAD value,sucrose synthetase and the angel between the leaf and horizontal plane.There was significant or extremely significant negative correlation between SPAD value,sucrose synthetase and bending degree of fruit branches.There was significant or extremely significant positive correlation between SPAD value,soluble protein,amino acid content,sucrose synthetase,sucrose invertase,GPT,GOT activity and internode diameter of main stem,fruit intemode diameter.Therefore,maintaining the physiological activity of leaves in reasonable scope is suitable for the formation of high yield plant types.There was significant or extremely significant negative correlation between SPAD value,soluble sugar,soluble protein,amino acid content,sucrose synthetase,sucrose invertase,GOT activity and the ratio of red-stem/total-stem for main stem,the ratio of yellow leaves/total leaves,the ratio of bolls/total leaves.Therefore,keeping the physiological activity of leaves in suitable range can make cotton plants form normal maturing phase. |
PDF Full Text Request