Effects of long-term no-tillage with straw mulch on photosynthetic characteristics of flag leaues and dry matter accumulation and translocation of winter wheat in dryland
Effects of long-term no-tillage with straw mulch on photosynthetic characteristics of flag leaues and dry matter accumulation and translocation of winter wheat in dryland
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发表时间：
2015
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通讯作者：
Wang Jian-b
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作者：
Wang Jian-b
【目的】冬小麦开花后的光合特性对干物质的积累和运输起着重要作用，而土壤水分是影响作物光合作用的最重要的环境因子。免耕的应用可以改善土壤环境，提高作物产量.为研究长期定位试验条件下秸秆覆盖免耕的蓄水保墒作用和冠层光合有效辐射的传输特性及其对小麦光合特性和干物质运转的影响，进行了长期定位试验。[方法] 1992年在黄土高原粉壤土上设置了免耕覆盖和常规耕作3个重复的试验小区，试验区土壤为低有机质、微碱性、干湿循环频繁的铬质雏形土。在不同耕作措施下，对休闲期和生育期的土壤水分、光合有效辐射、小麦旗叶光合特性、干物质积累和产量构成因素进行了测定。[结果]在休闲期和小麦生长期，0-160 cm土层中免耕土壤的蓄水量较常规耕作显著增加，平均增加12%。在土壤水分最低点（灌浆前期），免耕土壤含水量比免耕高21%（P < 0. 05）。01）。在抽穗期和灌浆期，免耕处理截获的冠层光合有效辐射比常规处理高163 μmol /（m2. s），差异最大（19. 5%）。3%）（P 0. 05）。NT措施下小麦冠层上部和下部都有利用光能的机会。与常规施肥相比，不施肥使灌浆前期气孔导度平均提高39%，CO2利用能力提高11%，WUE提高22%。从抽穗期到成熟期，免耕处理的净光合速率比常规处理高39%，收获期的粒重和全株重分别比常规处理高57%和46%（P 0. 05）。开花后干物质积累对籽粒的贡献率达64%。从产量构成因素来看，免耕对小麦穗数和千粒重的影响显著，分别比常规耕作提高31%和10%。结果表明，免耕栽培的产量比常规栽培高41%（P < 0. 05）。01）。研究表明，免耕秸秆覆盖的保水保墒能力可以缓解水分胁迫作用下小麦午间净光合速率的下降，使小麦光合作用维持在较高水平，同时，免耕还增强了花后干物质积累能力，花后干物质积累是免耕条件下籽粒干物质积累的主要来源，而常规施肥条件下，花前营养器官中积累的干物质是籽粒干物质积累的主要来源。[结论]长期免耕秸秆覆盖可显著改善晋南旱地土壤水分和光能截获能力，提高小麦光合特性、水分利用效率和干物质积累与运转，协调产量构成因素之间的关系，提高小麦产量。
【Objectives】Photosynthetic characteristics of winter wheat after flowering play an important role in dry matter accumulation and transportation,and soil moisture is the most important environmental factor which affects the crop photosynthesis. Application of no- tillage could improve the soil environment and increase the crop production. To study role of water reserving and soil moisture keeping under no- tillage with straw mulch practicein a long- term experiment,and transfer characteristics of canopy photosynthetically active radiation and their effects on photosynthetic characteristics and dry matter transportation of wheat,we conducted this experiment in the long- term plots. 【Methods】These plots were established in a silt loam soil in the Loess Plateau of China in1992,and consisted of no- tillage with straw mulch( NT) and conventional tillage( CT) with three replications.The soil of this semi- arid area is a Chromic Cambisol,which is low in organic matter and slightly alkaline and which is subject to frequent drying and wetting cycles. The soil moisture,and photosynthetically active radiation,flag leaf photosynthetic characteristics,dry matter accumulation and yield components of wheat were measured during the fallow period and wheat- growing period under different tillage practices. 【Results】During the fallow period and wheat- growing period,a significant increase of water- storage capacity under the NT practice is found in 0-160 cm soil depth compared with CT,with an average increase of 12%. At its lowest point( at the pre-filling stage),soil moisture under the NT practice is 21% higher than that of the CT practice( P 0. 01). The canopy photosynthetically active radiation intercepted under the NT practice is 163 μmol /( m2·s) higher than that of the CT practice at the heading and filling stages,which reaches the maximum difference( 19. 3%) at the pre-filling stage( P 0. 05),and both upper and bottom wheat canopies under the NT practice have opportunity to use light energy. Compared with the CT practice,the NT practice increases the stomatal conductance with an average of39% at the pre- filling stage,enhances the ability of carbon dioxide utilization by 11%,and improves WUE by22%. From the heading to mature stages,the net photosynthesis rate under the NT practice is 39% higher than that of CT,the grain weight and total plant weight at the harvest stage are 57% and 46% higher than those of CT respectively( P 0. 01),and the contribution of dry matter accumulation into grain after the flowering reaches64%. From the point of view of yield components,the NT practice had the significant effect on wheat spike number and thousand grain weights,31% and 10% higher than the CT practice respectively. The yield under the NT practice was 41% higher than the CT practice( P 0. 01). The study indicates that the ability of water reserving and soil moisture keeping under no- tillage with straw mulch practice could alleviate the decline of net photosynthesis rate in midday due to the action of water stress,and keep wheat photosynthesis at a high level.Meanwhile,the NT practice enhances the ability of dry matter accumulation after the anthesis,and the dry matter accumulation after the anthesis is the main source of dry matter accumulation into grain under the NT practice,while under the CT practice the dry matter accumulated in vegetative organs before the anthesis is the main source of dry matter accumulation into grain. 【Conclusions】The results indicate that the long- term no- tillage with straw mulch practice could significantly improve soil moisture and light interception ability, enhance wheat photosynthesis characteristics, WUE and dry matter accumulation and transportation, coordinate relationship between the yield components and increase wheat production in the dryland of the south of Shanxi Province.