| The experiment was implemented in Agricultural Experiment Station of Shandong Agricultural University in 2014-2016,based on 12 years of long-term located conversation tillage and straw returning farmland(started in 2002).Photosynthetic characteristics,chlorophyll fluorescence characterastics,dry matter accumulation and translocation,and yields of winter wheat and summer maize were measured during 2014-2016 cropping year.Split plot design was used: the main plot set two methods,which were straw returning(S)and straw removal(0),the deputy plot include conventional tillage(CT),no tillage(NT)and subsoiling(ST).Through the analysis of winter wheat and summer maize photosynthetic physiological characteristics,chlorophyll fluorescence characteristics,the dry matter accumulation and distribution into grain,analyzed the effects of tillage methods and straw returning on annual yield and its components from the perspective of photosynthetic physiology and dry matter accumulation and translocation.The main results were as follows:1.Effects of tillage methods and straw returning on leaf area index of winter wheat and summer maizeAlong with the advancement of growth period,winter wheat and summer maize population leaf area index,presents a trend of increased firstly and then reduced,winter wheat and summer maize reached the maximum respectively in flag stage and anthesis.Subsoiling can significantly improve the winter wheat leaf area index at all growth stages,no tillage can significantly increase it at the filling stage and mature stage,and crop residue returning also can significantly increase it.No tillage and subsoiling in summer maize growth period can improve leaf area index in two years.In 2015,summer maize jointing stage,big bell stage,anthesis and filling stage subsoiling respectively increased by 34.9%,30.8%,9.4% and 16.3%,in 2016 that was respectively increased 22.5%,22.0%,12.5%? 20.8%.In summer maize growth period,compared with CT0,NT0 and ST0,the leaf area index of CTS,NTS and STSincreased by 15.1%,16.8% and 5.7%,respectively,on average,in 2016 that was 13.1%,9.8% and 7.2%.No tillage,subsoiling and straw returning can effectively increase the photosynthetic area,raise the radiation use efficiency of winter wheat and summer maize.2.Effects of tillage methods and straw returning on photosynthetic characteristics of winter wheat and summer maizePhotosynthetic rate,stomatal conductance and transpiration rate of winter wheat flag leaves and summer maize ear leaves showed the same trend in two years,all reached the maximum at the anthesis,and then reduced with the reproductive growth and grain filling.In the growth stage of winter wheat and summer maize,intercellular CO2 concentration showed opposite trend with the photosynthetic rate and stomatal conductance,which illustrated the non-stomatal factors limited photosynthesis,one of the reason that subsoiling,no tillage and straw returning improved the photosynthetic rate was that they improved use ability of intercellular CO2 and reduced the non-stomatal limitation.Subsoiling and no tillage can significantly improve the photosynthetic performance of winter wheat and summer maize in later growth stage.In 2014-2015 winter wheat later filling stage,photosynthetic rate of subsoiling and no tillage increased by 63.2% and 47.7% on average,stomotal conductance increased 55.4% and 39.8% on average,and transpiration rate increased 30.7% and 23.4%;the same as the year of 2015-2016,the increasement of photosynthetic rate was 38.8% and 26.3%,that of stomotal conductance was 70.7% and37.1%,that of transpiration rate was 23.8% and 11.1%.Subsoiling and no tillage can also significantly improve the photosynthetic performance of in filling stage in two years,and the stomotal conductance increased 49.1% and 36.0% respectively,transpiration rate increased40.1% and 19.0% in 2015;and in 2016,the stomotal conductance increased 46.1% and 31.3%respectively,transpiration rate increased 40.4% and 18.4%.The photosynthetic performance of winter wheat and summer maize under subsoiling were better than no tillage.Straw returning also can significantly improve the photosynthetic performance of winter wheat and summer maize in later growth stage.In 2014-2015 winter wheat growth stage,the photosynthetic rate,stomotal conductance and transpiration rate of treatment with straw returning increased respectively 13.6%,18.0% and 12.2% on average;in 2015-2016 winter wheat growth stage,respectively increased 11.3%,25.7% and 12.1% on average;in 2015 summer maize growth stage increased 9.1%,7.1% and 13.9%;in 2016 summer maize growth stage increased 9.6%,6.9% and 10.5%.Both subsoiling and straw returning can significantly improve the apparent quantum efficiency,improve photosynthetic capacity under the weak light,to extend photosynthesis time,and also can achieve higher light saturation point and photosynthetic rate of winter wheat and summer maize in filling stage.3.Effects of tillage methods and straw returning on chlorophyll fluorescence characteristics of winter wheat and summer maizeSubsoiling,no tillage and straw returning can significantly increased chlorophyll content of the winter wheat flag leaves and summer maize ear leaves,maintained function leaves photosynthetic capacity at a higher level.In 2014-2015 winter wheat later filling stage,subsoiling and no tillage significantly increased 101.5% and 72.0% respectively;in2015-2016 increased 120.6% and 67.1%.In 2015 summer maize filling stage the treatment of subsoiling,no tillage and straw returning increased 30.8%,16.3% and 13.7%;in 2016 that increased 26.2%,13.7% and 15.0%,respectively.Higher chlorophyll content in later growth stage can maintain leaves green,contribute to the late dry matter accumulation,and provide sufficient raw materials for grain-filling.There were no significant difference between all treatments of Fv/Fm,illustrated that tillage methods and straw returning did not lead to stress environment.In 2015 and 2016 winter wheat later filling stage,?PSII of subsoiling increased 48.2% and 43.1% than conventional tillage,straw returning increased 19.7% and 17.0%;in summer maize filling stage,that of subsoiling increased 90.0% and 90.9%,straw returning increased 27.3% and26.8%.In 2014-2015 winter wheat later filling stage,ETR of subsoiling and no tillage were63.1% and 20.9% higher than conventional tillage,in 2015-2016,that were 63.2% and 20.7%.Subsoiling was more beneficial to improve chlorophyll fluorescence activity than no tillage.4.Effects of tillage methods and straw returning on dry matter accumulation and allocation of winter wheat and summer maizeDry matter accumulation of subsoiling and no tillage in the growth period of winter wheat and summer maize were significantly higher than that of conventional tillage,and that of subsoiling were higher than no tillage.Straw returning can also improve dry matteraccumulation in the growth period.Subsoiling,no tillage and straw returning can significantly increase the allocation of dry matter into grain,which provided physiological basis to high yield,and they also increased dry matter accumulation after anthesis contribution ratio into grain.Subsoiling,no tillage and straw returning all can improve the dry matter accumulation after flowering and redistribution ability,were advantageous to the photosynthate after flowering to the grain distribution,provided a physiological basis for high yield.5.Effects of tillage methods and straw returning on yield and its components of winter wheat and summer maizeFor the yield components,in 2014-2015 and 2015-2016,subsoiling and no tillage significantly improved the winter wheat spike,grain numbers per spike and gained ultimately yield enhancement.In two years,the grain numbers per spike under subsoiling and no tillage increased by 14.9% and 9.9% on average,the 1000-grain weight increased by 15.5% and7.2%,and yield increased by 12.0% and 5.6% on average.Straw returning can improve the number of ears,grain numbers per spike and 1000-grain weight,respectively,7.5%,7.6% and9.2%,thus improve the yield,increased by 6.5% on average.For two years summer maize yield,the grain numbers per ear and 1000-grain weight under subsoiling increased by 7.9%and 7.9% respectively,the average yield increased by 18.9%;the grain numbers per ear and1000-grain weight of no tillage increased by 4.5% and 4.5% respectively,the yield increased by 9.9% on average.In two years,straw returning can improve the number of ears,grain number per spike of summer maize,increased 3.0% and 3.5%,respectively,and the yield increased by 10.9% on average.Subsoiling,no tillage and straw returning can improve winter wheat and summer maize functional leaf area index,and photosynthetic performance,such as photosynthetic rate,stomatal conductance and transpiration rate,and improve chlorophyll fluorescence activity,such as chlorophyll content,? PSII and ETR in all growth stage,especially in the later growth stage.And that three methods also can improve use ability of intercellular CO2 and reduce the non-stomatal limitation,improve the ability of dry matter accumulation,enhance dry matter accumulation after the anthesis and contribution ratio to grain,coordinate the relationship between the yield components,finally improve the annual yield.Among all treatments,subsoiling with straw returning performed the best,followed the no tillage with straw returning. |
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