Quantitative Study On The Effects Of Tillage And Fertilization On Organic Carbon And Assimilates Transformation In Soil-wheat System Using ¹³C Method

¹³C stable isotope tracer technology is an important tool and effective means to study the accumulation and distribution of photosynthetic carbon in soil-crop system.In order to promote the rational tillage and fertilization in wheat field,pot experiment and field experiment were carried out.Bainong 418 was used as the experimental material,and different tillage and fertilization treatments were set up by two-factor design.At the same time,based on ¹³CO₂ pulse labeling technology,the effects of tillage and fertilization on organic carbon content,photosynthetic characteristics,assimilate accumulation and distribution in soil-wheat system were quantitatively studied to clarify the regularity of assimilate transformation under different tillage and fertilization modes.It can provide a theoretical basis for rational selection of tillage and fertilization modes in Henan Province,so as to ensure high and stable yield of wheat.The main conclusions are as follows:1.Application of organic fertilizer increased the organic carbon content of wheat field soil and wheat spike.The organic carbon content in soil-wheat system was higher under the treatment of organic fertilizer+chemical fertilizer（OF）in pot experiment at different growth stages,and it was higher under the treatment of no-tillage mode in field experiment,while the organic carbon content in wheat plants was different under different treatments.Adding organic fertilizer in pot experiment was beneficial to increase the content of organic carbon in soil-wheat system,while it was only beneficial to increase the content of organic carbon in wheat spike in field experiment.Variance analysis showed that different tillage and fertilization patterns had significant effects to organic carbon content in Soil-Wheat system（P<0.05）,except at maturity.2.Adding organic fertilizer and deep tillage with organic fertilizer treatment could improve the photosynthetic characteristics of wheat.During the whole growth period,the SPAD,F_v/F_m and P_n values of wheat increased first and then decreased,reaching the peak at anthesis.The SPAD value,F_v/F_m value and P_n value under the treatment of OF were higher than those under the treatment of chemical fertilizer only（CF）in pot experiment in each period.In the field experiment,the SPAD value under the treatment of deep tillage organic fertilizer（DTF）was at a higher level,the F_v/F_m value and P_n value were the highest.The photosynthetic characteristics under different tillage modes were as follows:the treatment of increasing organic fertilizer was larger than that under the treatment of chemical fertilizer only（except SPAD value under no-tillage mode）.The effects of different tillage and fertilization patterns on photosynthetic characteristics of wheat were significant（P<0.05）.3.Application of organic fertilizer and deep tillage with organic fertilizer treatment were beneficial to increase above-ground dry matter accumulation of wheat.With the advance of growth period,the above-ground dry matter total accumulation of wheat increased first and then inclined to stable value The quality of spike increased gradually,and it was the largest at maturity.The quality of leaf decreased gradually,and it was the largest at jointing stage.The quality of stem sheath increased first and then decreased,reaching the maximum at anthesis.In pot experiment,the above-ground dry matter total accumulation and above-ground organ quality under the treatment of OF were larger than those under the treatment of chemical fertilizer（spike at maturity only）.The above-ground dry matter total accumulation and above-ground organ quality under the deep tillage with organic fertilizer treatment in the field experiment were larger than other treatments,and those under shallow tillage and no-tillage model with adding organic fertilizer were larger than chemical fertilizer only.4.The accumulation and distribution of net input photosynthesis ¹³C were affected by tillage mode,fertilization mode,marker period and sampling period.In the field experiment,the effects of the same tillage mode on ¹³C accumulation and distribution in different organs were different in different fertilization modes and sampling periods.In pot experiment and field experiment,the application of organic fertilizer was beneficial to the accumulation of photosynthetic carbon in stem sheath,and the transport of photosynthetic carbon to spike at filling stage.And it also increased the ¹³C distribution rate in stem sheath after marking at jointing stage and anthesis,and in spike after marking at filling stage.With the development of wheat growth period,the total fixed amount of photosynthetic carbon in above-ground of all treatments decreased gradually,and the photosynthetic carbon in leaves and stem sheaths gradually transported to spikes.The ¹³C content and ¹³C distribution rate in leaves and stem sheaths decreased and spikes increased.At different sampling stages,the ¹³C distribution rates of above ground organs of wheat treated with different treatments were significantly different,with larger spikes and stem sheaths and smaller leaves.5.Adding organic fertilizer and deep tillage with organic fertilizer treatment were beneficial to increase wheat yield.In pot experiment,the wheat yield under the treatment of OF was higher than CF,and the treatment of DTF in field experiment was higher than others.In pot experiment and field experiment,the number of grains per spike,1000-grain weight and yield showed that the application of organic fertilizer were greater than that of chemical fertilizer,which indicated that the application of organic fertilizer could increase the yield of wheat by increasing the number of grains per spike and 1000-grain weight of wheat.6.The correlation analysis showed that the net input photosynthetic ¹³C content and distribution rate could be increased by increasing the organic carbon content and dry matter accumulation of wheat plants;the net photosynthetic rate and yield could be increased by increasing the organic carbon content,SPAD,F_v/F_m and dry matter accumulation of wheat plants.In conclusion,adding organic fertilizer and deep tillage with organic fertilizer could increase the content of organic carbon in Soil-Wheat system,improve the photosynthetic capacity of wheat and the transport of photosynthates to spikes,which is conducive to the accumulation of assimilates in wheat spikes and ultimately to the increase of wheat yield.