【作者】 薛兰兰；

【导师】 王龙昌；

【作者基本信息】 西南大学 ， 生态学， 2011， 博士

【摘要】 秸秆覆盖是一种高效节水的作物栽培技术,在改变农田下垫面性质和能量平衡、调节土壤温度及改善土壤水分状况等方面具有显著作用,具有达到提高经济产量、减少水分无效消耗、提高水分利用效率的目的。秸秆覆盖是保护性耕作的重要方面,对农业生产和农业可持续发展具有重要意义。秸秆覆盖可以蓄水保墒；改善土壤微环境；减少水土流失；调节土壤水、肥、气、热；促进作物生长发育和光合作用。本文研究了秸秆覆盖保护性种植油菜的农田土壤养分动态变化及干旱胁迫下大豆生理生化响应机制。主要结果如下1.秸秆覆盖保护性种植油菜农田土壤养分效应和油菜生长发育和产量的研究本文旨在研究秸秆覆盖保护性种植下油菜的生长发育、整个生育期内土壤养分动态变化以及产量效应。试验在西南大学试验农场进行,设置8个处理：①无秸秆覆盖,②水稻秸秆3750kg/hm2覆盖,③水稻秸秆7500kg/hm2覆盖,④玉米秸秆3750kg/hm2覆盖,⑤玉米秸秆7500kg/hm2覆盖,⑥水稻秸秆7500kg/hm2覆盖无农作物,⑦水稻秸秆7500kg/hm2覆盖+速腐剂无农作物,⑧水稻秸秆7500kg/hm2覆盖+速腐剂。于油菜生长的不同时期,分层取样。通过土壤养分动态变化分析和油菜生长和产量效应的研究得出以下结论：(1)不同类型秸秆覆盖处理下土壤有机质,0—10cm和10—20cm土层的土壤有机质含量变化相近,各个水平梯度间的差异不明显,有速腐剂处理的有机质含量要相对较高,变化差异也相对较大；秸秆覆盖处理下,土壤全氮0—10cm土层与10—20cm土层呈“增加——降低——增加”的趋势；不同类型秸秆覆盖处理下土壤碱解氮0—10cm和10—20cm士层变化相似,呈“下降——增长——下降”的变化趋势；秸秆覆盖不同处理土壤全磷在0—10cm和10—20cm土层变化相似,均出现波动增高的趋势;土壤有效磷0—10cm和10—20cm土层变化—致,前期微小增长,接着下降,结实成熟期增高；土壤全钾在0—10cm出现先增后降的趋势,10—20cm土层,先增长后下降然后增长；土壤速效钾的变化与全钾各土层变化一致；土壤的pH值在0—10cm和10—20cm土层变化一致,随着作物生长季节的推移,出现波动增长。收获后期秸秆覆盖农田十壤养分的研究揭示出：在有作物生长的情况下,秸秆覆盖对耕层土壤有机质的积累没有明显作用；秸秆覆盖对耕层土壤氮素的供应有明显的影响,总体上全氮随着秸秆覆盖量的增加而增加：同水平玉米秸秆覆盖处理较水稻秸秆覆盖处理对碱解氮的积累作用较明显；秸秆覆盖处理大部分可以提高耕层土壤全钾；不同秸秆对耕层土壤钾素的影响不同,水稻秸秆覆盖处理对土壤有效磷、全钾和速效钾的效果优于玉米秸秆覆盖。无农作物的条件下,全量覆盖耕层士壤的有机质含量出现积累。速腐剂的使用对有机质积累没有影响;速腐剂的使用可以增加土壤全氮的累积,而碱解氮的积累与速腐剂的使用关系不大;速腐剂的使用对补充土壤全磷有重要作用；无农作物的情况下速腐剂可以增加耕层土壤全钾的积累。(2)秸秆覆盖对油菜的营养生长和生殖生长有显著促进作用。秸秆覆盖可以显著提高油菜的株高,增加分枝数和花序数,速腐剂的加施对营养生长的效果明显,但对生殖生长的效果未显现出来。(3)秸秆覆盖保护性种植可以提高油菜的产量,速腐剂对油菜产量的增加尤为明显。同种秸秆不同水平覆盖处理下,油菜的产量随覆盖量的增加有增长趋势。2.秸秆覆盖大豆生理生化响应机制的研究为了研究秸秆覆盖下大豆生长、光合作用、叶绿素、可溶性蛋白、游离脯氨酸、丙二醛(MDA)以及抗氧化物酶系统对干旱的响应机制,小麦秸秆不同量覆盖大豆的生理生化响应机制研究中,设置无覆盖,3750 kg/hm2,7500 kg/hm2,11000 kg/hm2和14750 kg/hm2五个处理。秸秆不同类型不同量覆盖大豆的生理生化响应机制研究中设置无覆盖,小麦秸秆11000kg/hm2覆盖,小麦秸秆14750 kg/hm2覆盖,玉米秸秆11000 kg/hm2和14750 kg/hm2覆盖五个处理。通过对大豆生长发育指标和生理生化响应机制的探讨得出：(1)秸秆覆盖可以促进细胞伸长,显著提高大豆的株高,且“晋豆21号”株高总体上高于“西豆7号“,但二者在秸秆覆盖不同处理下增长程度和增长量不同。小麦秸秆覆盖和玉米秸秆覆盖均可以促进大豆叶片数的增加,且随着秸秆覆盖量的增加而增加,但其增加量因秸秆类型的差异而不同,就大豆叶片数而言,小麦秸秆覆盖的效果优于玉米秸秆覆盖。小麦秸秆覆盖处理下大豆的叶面积在一定程度随秸秆覆盖量的增加呈增加趋势,但并不是无限增加。秸秆覆盖利于大豆茎的横向生长,秸秆覆盖提高了大豆的茎粗,且随着秸秆覆盖量的增加而增加。(2)秸秆覆盖在水分匮乏的情况下能促进大豆的光合作用,且与秸秆覆盖量有很大关系。小麦秸秆覆盖保护性种植条件下,大豆的蒸腾速率在一定程度上随着秸秆覆盖量持续增加,但当秸秆覆盖量继续增加,则出现下滑,这与同条件下净光合速率的研究一致。秸秆覆盖可提高大豆叶片的气孔导度,且总体上气孔导度随着秸秆覆盖量的增加而加大。胞间CO2浓度减少到一定程度随着秸秆覆盖量的增长而增加,这与净光合速率和蒸腾速率的研究结果正好相反。空气和叶片的温差,随着秸秆覆盖量的增加而加大。(3)秸秆覆盖处理下大豆叶片叶绿素含量的变化同时受干旱进程、秸秆覆盖量和覆盖物类型的影响；总体上玉米秸秆覆盖对叶绿素a的调节作用明显。秸秆覆盖对叶绿素的变化具有调节作用,其调节作用和限度与秸秆覆盖量、干旱时间的长短以及作物本身的耐受性相关。(4)小麦秸秆不同量覆盖下,大豆可溶性蛋白含量随着干旱的加强持续下降,但秸秆覆盖可溶性蛋白含量的下降得到明显缓解。秸秆不同类型不同量覆盖大豆叶片可溶性蛋白含量随着干旱胁迫的增强而增加。在干旱胁迫下可溶性蛋白含量变化不一致,秸秆覆盖可溶性蛋白含量的变化因秸秆覆盖量、秸秆类型、作物品种和胁迫时间而存在差异。(5)大豆在干旱胁迫过程中,叶片游离脯氨酸含量随着胁迫程度的增强持续增长。秸秆覆盖在大豆防御干旱方面起重要作用,可以降低脯氨酸含量的积累,降低量与秸秆覆盖类型和覆盖量有关。(6)小麦秸秆不同量覆盖处理下,MDA含量随干旱程度的加强呈现增长趋势,随着秸秆覆盖量的增加,MDA含量在总体上降低。干旱胁迫丙二醛含量的变化与水分胁迫历时有关,小麦秸秆覆盖对大豆丙二醛具有补偿效应,可以在一定程度上缓解细胞膜脂氧化反应对细胞膜以及作物的伤害。干旱胁迫下不同秸秆不同量覆盖处理,干旱初期大豆叶片丙二醛含量随玉米秸秆覆盖量的增大而增加,小麦秸秆覆盖处理大豆叶片丙二醛随秸秆覆盖量的增加而下降；中期丙二醛含量随着干旱时间的延长不断积累,即干旱时间越长植物受到的膜脂过氧化伤害越大,而秸秆覆盖可以在一定程度上降低丙二醛含量的积累,而且降低的程度与秸秆覆盖量和覆盖类型相关。(7)秸秆覆盖在保护膜系统免受自由基伤害上具有重要调节作用,轻度干旱下调节作用明显。超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)三种保护酶在大豆干旱胁迫下起协调作用,哪一种酶调节起主导作用因大豆品种、胁迫程度、胁迫时间和秸秆覆盖的差异而改变。(8)通过模糊综合评价得出：小麦秸秆不同量覆盖处理小麦秸秆11000 kg/hm2覆盖处理“西豆7号”抗旱能力最强,对照无覆盖处理大豆抗旱能力最差；秸秆不同类型不同量覆盖中玉米秸秆14750 kg/hm2“晋豆21号”抗旱能力最强,玉米秸秆11000 kg/hm2覆盖处理次之。更多还原

【Abstract】 Straw mulch is a highly effective water-saving technology, which plays significant role in changing underlying surface properties and balance, regulating soil temperature and improving soil moisture status. The main objective of using straw mulch is to increase economic output, reduce water loss and improve the water use efficiency. It is widely used for successful crop production under water-limiting condition, leads to sustainable development, and is an important aspect of conservation tillage. Straw mulch could hold soil water, improve soil micro-climate, reduce soil erosion, adjust soil water fertilizer gas heat, which is conducive for crop growth, and increased photosynthesis. In the present study we evaluated the performance of straw mulch cultivation on soil nutrients dynamic changes in rapeseed and its possible role in physiological and biochemical responses in soybean under drought stress. Main results are as follows: 1. The effect of straw mulch conservative cultivation on soil nutrients, growth and yield components in rapeseedThe study aimed to investigate the growth, soil nutrient dynamic change and yield of rapeseed under straw mulch conservative cultivation. The research work was carried out at the experimental farm of Southwest University, which comprised of a set of 8 treatments viz.:①no straw mulch,②3750kg/hm2 rice straw mulch.③7500kg/hm2 rice straw mulch,④3750kg/hm2 maize straw mulch,⑤7500kg/hm2 maize straw,⑥7500kg/hm2 rice straw mulch no crop treat,⑦7500 kg/hm2 rice straw mulch+rottening agent and no crop treat.⑧7500 kg/hm2 Rice straw mulch+rottening agent. Soil sampling was carried out at various developmental stages of rapeseed from varying soil depths. The analysis of the soil nutrient dynamic change, growth and yield of rapeseed indicated that:(1) Under different straw mulch treatments the change of soil organic matter on 0-10cm and 10-20cm layer was similar, and the differences between the various levels of straw mulch were not significant. The treatment where rottening agent was used had significantly higher organic matter contents. The soil total N under straw mulch followed the "increased-decreased-increased" trend. whereas the alkali-hydro nitrogen contents followed the "down-up-down" trend. The soil total P in 0-10cm and 10-20cm soil layer were volatility elevated and soil available P layer were first increased then declined. The trend of total K in 0-10cm was" increase-decrease" and in 10-20cm soil layer was opposite. The readily-available potassium in 0-10cm and 10-20cm soil layer followed the same trends as of total potassium. The soil pH value in 0-10cm and 10-20cm soil layer was consistent, which followed the increasing trend as the crop grew.(2) When we investigating the soil nutrients after harvest under straw mulch, the experimental results revealed that application of straw mulch had non-significant effect on the soil organic matter accumulation; the total nitrogen with the straw mulch increased;the same level of maize straw mulch treatments have more pronounced effect on the accumulations of nitrogen than rice straw mulch treatments; the straw mulch treatments improved the soil total potassium; the impact of different straw mulch treatments on soil potassium was variable, the various rice straw mulch treatments resulted in better soil available phosphorus, total potassium and readily-available potassium than the effects of maize straw mulch treatments; the use of rottening agent had no effect on accumulation of soil organic matter and alkali-hydrolysable nitrogen, but it resulted in increased accumulation of total soil nitrogen and total phosphorus, in the case of non-crop the rottening agent increased the accumulation of soil potassium.(3) Straw mulching had a significant effect on promoting the vegetative and reproductive growth of rapeseed. In our study, straw mulching significantly improved the rapeseed plant height, number of branches per plant and inflorescence, whereas rottening agent significantly improved the vegetative growth. The effect rottening agent on reproductive growth was not considerable. Rottening agent produced significantly higher yield than the same level of straw mulch treatments. Within one type of straw the yield of rapeseed was continuously enhanced follow the quantity of straw mulch.2. Physio-biochemical response of soybean to straw mulch To investigate the influence of straw mulch on growth, gas exchange, chlorophyll contents, soluble protein, free proline, lipid peroxidation and the activities of antioxidative enzymes in soybean under drought stress, a pot experiment was carried out in rain-protected wire-house of Southwest University. Chongqing. China. Soybean plants were supplied with varying wheat straw mulch treatments at true leaf stage viz:control (no straw mulch).3750 kg/hm2,7500 kg/hm2,11000 kg/hm2 and 14750 kg/hm2 and subjected to drought stress at blooming stage. An other pot experiment was carried out to investigate the response of soybean to varying type and different quantity of wheat and maize straw mulch treatments under water-deficit conditions, with following treatments: 11000kg/hm2 wheat straw mulch,14750 kg/hm2 wheat straw mulch,11000 kg/hm2 maize straw mulch and 14750kg/hm2 wheat straw mulch. The observations indicated that: Straw mulch promoted the cell elongation significantly which ultimately resulted in increased soybean plant height. The height of "Jin dou 21" was higher than the "xi dou 7". but between two varieties the increment of plant height under different mulch treatments was non-significant. Wheat straw and corn straw mulch both increased the number of soybean leaves per plant depending upon the type and quantity of straw mulch, but the effect of wheat straw mulch was more pronounced than maize straw mulch. Wheat straw mulch treatments enhanced the leaf area of soybean, the leaf area increased follow the quantity of straw mulch. The stem diameter of soybean plants grew following the amount of straw mulch applied.(2) Straw mulch significantly enhanced the photosynthesis (Pn), intercellular CO2 concentration (Ci), transpiration rate (E), stomatal conductance (Gs) and D-value (Ta-T1) (difference between air temperature and leaf temperature) over control treatment. All these gas exchange parameters were improved depending upon the quantity of wheat straw mulch; significantly highest Pn and E was observed in the treatment where wheat straw was applied at the rate of 11000kg/hm(3) The chlorophyll contents in soybean leaves altered noticeably during drought stress depending upon the type and the quantity of straw mulch. The observations indicated that chlorophyll contents proportionally decreased with the progression of drought stress but linearly increased with increase in straw mulch quantity.(4)Under varying levels of wheat straw, the contents of soluble protein in soybean continued to decline along with the prolongation of drought stress, but the straw mulch significantly alleviated the decrease of soluble protein content. The soluble protein increased with the drought stress under different type and amounts of straw mulch. The change of soluble protein content under drought stress was inconsistent and it was different because of types of straw mulch, crop varieties and stress time.(5) During drought stress in soybean, free proline content increased with the drought stress level. Straw mulch played an important role in drought-resistance of soybean by reducing the accumulation of proline content, but the amount of reducing was relevant to type and quantity of straw mulch.(6) The activities of Malondialdehyde (MDA) in leaves gradually increased as the water stress prolonged and decreased following the straw quantity in the treatments of different amount of wheat straw mulch. The contents of MDA changed with the progression of water stress. Wheat straw mulch led to drought ameliorating effect in drought-stressed soybean plants by decreasing the MDA contents which ultimately played a significant role in mitigation of lipid peroxidation on cell and crop.Under drought stress depending upon different type and quantity of straw mulch, the contents of MDA were increased at beginning of stress by following the amount of maize straw mulch and declined with the quantity of wheat straw mulch. In the middle of water deficit MDA content increased with the prolongation of drought, that the longer the plant suffered drought the greater lipid peroxidation damage. Straw mulch up to certain extent reduced the accumulation of MDA and the reduction was related to the quantity and type of straw mulch.(7) Straw mulch was able to enhance the activities of antioxidative system to mitigate the drought-induced oxidative damage in soybean plants. The effect of straw mulch on protective antioxidative system under slight drought conditions was significant. Superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were coordinated to play a positive role in soybean under drought stress depending upon soybean varieties, stress level, timing of stress and the different quantity of straw mulch.(8) Through the comprehensive evaluation it is clear that different amounts of wheat straw mulch contributed to drought resistance of "xi dou 7",11000 kg/hm2 got highest and control in worst. Among the different types and quantity of straw mulch the treatment of 14750 kg/hm2 maize straw mulch played a significant role in drought resistance, followed by 11000 kg/hm2 maize straw mulch in "jin dou 21"更多还原