【作者】 陶先萍；

【导师】 张旺锋；

【作者基本信息】 石河子大学 ， 作物栽培学与耕作学， 2013， 博士

【摘要】 根土界面是土壤水分和养分进入植物体内的主要通道，根系是根土界面的核心内容与物质基础，其分布与功能直接或间接地影响着地上部生长以及整个植株的生存和发展。在作物赖以生存的农田土壤环境中，水肥是对作物根系影响最经常、也是最易被人工调控的因素。棉花是我国干旱区绿洲农业最重要的经济作物，研究通过改进灌溉技术和施肥方式，变动根土界面水肥状况及其在剖面的分布，以优化棉花根系形态与结构，调节生理特性，增强棉株对水肥的吸收能力，提高利用效率，对干旱区棉花大面积节水高产高效栽培具有重要意义。本研究在管栽条件下，从根域容积与滴灌深度两方面入手，设置不同的水氮用量，采用膜下滴灌随水施肥技术模式，研究了棉花根系生长空间受限条件下植株形态与生理的适应性变化及与产量形成的关系；同时进行大田试验，研究了不同产量水平下棉花根系形态生理及叶片生理特性的变化趋势；在综合研究的基础上，探讨了改变根系生长环境对根系形态生理的影响及与地上部生长发育的关系。主要研究内容与结果如下：1、研究了根域限制条件下不同水氮供应量对棉花根系形态特征的影响。根域限制条件下，棉花各土层根系根表面积指数（RAI）、根长密度（RLD）、根体积密度（RVD）、根质量密度（RMD）、根系生物量与根冠比均低于对照。不同水氮处理间上述各参数均表现为W₀N₀（水氮亏缺）＞W₁N₀（氮素亏缺）＞W₀N₁（水分亏缺）＞W₁N₁（水氮适量），根域限制与水氮供应均使各土层根量减少。2、研究了根域限制条件下不同水氮供应量对棉花根系生理活性的影响。根域限制条件下，根系抗氧化保护酶系（SOD、POD、CAT）活性均显著低于对照。水氮供应能有效调节根系生理特性，不同水氮处理间棉花根系抗氧化保护酶系活性表现为W₁N₁＞W₀N₁＞W₁N₀＞W₀N₀。在棉花根系生长受限条件下，优化生育期间水氮供应，可以增强根系抗氧化保护酶系活性，延缓根系衰老。3、研究了根域限制条件下不同水氮供应量对棉花叶片生理特性及产量的影响。与对照相比，相同水氮供应条件下，根域限制处理棉花从开花期至盛絮期叶片抗氧化保护酶系（SOD、POD、CAT）活性、叶片净光合速率（Pn）、气孔导度（Gs）和光化学猝灭系数（qp）均显著降低，但潜在最大光化学效率（Fv/Fm）、实际光化学效率（ΦPSII）未受到影响；盛花期和盛絮期根系生物量均显著降低，但地上部生物量、蕾铃生物量及籽棉产量均显著高于对照。根域限制条件下适量水氮供应处理的地上部生物量和蕾铃生物量均显著增加，最终单株铃数、单铃重和籽棉产量均显著高于其它处理。棉花根域容积受限条件下，通过优化生育期水氮供应，可以改善叶片光合性能、增加地上部干物质积累量及其向生殖器官分配比例。4、研究了不同灌溉深度条件下不同水氮供应量对棉花根系形态特征的影响。0-40cm土层根系RVD、RMD、RAI与RLD均表现为CK（地表滴灌）＞H₀（滴灌深为地下20cm）＞H₁（滴灌深为地下40cm），而在40-80cm与80-120cm土层，上述各参数均表现为CK＜H₀＜H₁。水氮供应显著（P<0.05）减小根量，不同水氮处理间根系各形态参数、根系生物量与根冠比均表现为W₀N₀＞W₁N₀＞W₀N₁＞W₁N₁。在土壤上层（0-40cm土层），随滴灌深度的增加及水氮供应均使根量减小，其中滴灌深度是主效因子。在灌溉深度下的各土层，水氮供应是根量减小的主效因子。5、研究了不同灌溉深度条件下不同水氮供应量对棉花根系生理特性的影响。不同灌溉深度间各土层根系抗氧化保护酶系（SOD、POD与CAT）活性均表现为H₀＞CK＞H₁，不同水氮供应间均表现为W₁N₁＞W₀N₁＞W₁N₀＞W₀N₀。表明地下浅层滴灌与水氮供应均有助于提高根系抗氧化保护酶系活性，从整体上能延缓根系衰老。水氮供应是决定根系保护酶系活性的主效因子，适度水氮供应（W₁N₁）配合灌溉深度20cm（H₀）处理下根系保护酶系活性最高。6、研究了不同灌溉深度条件下不同水氮供应量对棉花叶片生理特性及产量的影响。灌溉深度、水氮处理对棉花叶片抗氧化保护酶系（SOD、POD与CAT）活性、叶片气体交换参数（Pn、Gs）、叶绿素荧光参数（Fv/Fm、ΦPSⅡ、qP）的影响与根系保护酶系活性的影响结果一致，灌溉深度与水氮供应的具有互作效应。植株地上部生物量与产量在各处理间表现均与Pn相同；而根系生物量、根冠比的表现与之相反。表明浅层滴灌配合适宜的水氮运筹有利于协调棉花植株地上部与地下部生长、缓解营养生长与生殖生长之间的矛盾，使资源达到最优化。7、研究了不同产量水平条件下大田棉花根系生长发育特性。在规模化种植的膜下滴灌棉田，随产量水平的提高，全土层RLD、RAI、RVD与RMD降低；根系与叶片抗氧化保护酶系（SOD、POD与CAT）及硝酸还原酶（NR）活性均随产量水平提高而增加；根冠比和根系生物量随产量水平的提高而降低，而地上部生物量、产量各构成因子均随产量水平提高而增加。在产量水平较高的棉田，根冠比降低与根系生理活性增强均能促进地上部的生长发育，优化产量结构与形成，最终提高产量。结合管栽试验与大田试验结果，综合分析棉花根系形态生理特征与地上部生物量及产量的关系，认为在干旱区膜下滴灌条件下，棉花产量水平提高，需要较高的地上部生物产量，但不一定需要较大的根系生长，根系适度缩小，可以降低根系冗余。从本文结果来看，大田棉花的根冠比以0.21-0.32为宜。通过膜下滴灌水肥调控，控制根系大小，提高根系生理（SOD、POD、CAT与NR）活性可作为棉花高产栽培的主攻方向，也是棉花品种遗传改良的根系形态与生理选择指标。更多还原

【Abstract】 Root-soil interface is the main channels for soil water and nutrients into plants. Root isthe core content of the root-soil interface and the material basis, whose distribution andfunction directly or indirectly influence the growth of the aboveground and the survival anddevelopment of the whole plant. Cotton is the most important economic crop in oasisagriculture in arid areas in China. In the research, through improving irrigation andfertilization ways, changing root soil water status and its distribution in the section tooptimize the cotton root morphology, structure, and physiological characteristics. In turn, toenhance cotton plants water and fertilizer absorption and utilization efficiency, furthermore, torealize the high-efficient and high-yield and water-saving cultivation of cotton in arid areas isvery important. This research was conducted in pipe cultivation condtion and focused on twoaspects of the root domain volume and the irrigation depth, different water and nitrogenamount were set and the model of drip irrigation under membrane with fertilization wasadopted to study the relationship of morphological and physiological adaptations and yieldformation on cotton under the condition that root growth space is confined. At the same timethe field test experiment was carried out and the change trend of root morphological andphysiological and leaf physiological characteristics under different yield levels were observed.On the basis of comprehensive study, the influence of changing root growth environment onroot morphological and physiological traits and its relationship with the aboveground growth.The main research contents and results were as follows:1. Influence of water and nitrogen supply amount on root morphological characteristicsof cotton in root restriction was studied. Root surface area index （RAI）, the root lengthdensity （RLD） and root volume density （RVD） and root mass density （RMD）, root systembiomass and root shoot ratio were lower than controls in the root restriction. The aboveparameters among different water and nitrogen treatments were rank in the orde of W₀N₀（water and nitrogen deficit）>W₁N₀（nitrogen deficit）>W₀N₁（water deficit）>W₁N₁（water andnitrogen in moderation）. The root restriction and water and nitrogen supply all reduce the rootquality.2. Influence of water and nitrogen supply amount on root physiological activity of cottonin root restriction was studied. Root antioxidant protective enzymes （SOD, POD, CAT）activity were significantly lower than control. Water and nitrogen supply effectively adjustedthe root growth. The activity of root protective enzyme system among different water andnitrogen treatments were rank in the orde of W₁N₁>W₀N₁>W₁N₀>W₀N₀. Under the conditionof root restriction, optimization of water and nitrogen supply during growth stages, enhancethe activity of root antioxidant protective enzyme system, postpone root senescence.3. Influence of water and nitrogen supply amount on leaf physiological characteristics and yield of cotton in root restriction was studied. Compared to the control, at the same waterand nitrogen supply, from flowering to full boll openning stage, leaf antioxidant protectiveenzymes （SOD, POD, CAT） activity, leaf net photosynthetic rate （Pn）, stomatal conductance（Gs） and light chemical quenching coefficient （qP） were significantly lower, but the potentialmaximal photochemical efficiency （Fv/Fm）, actual photochemical efficiency （ΦPSII） werenot affected. At both full flowering stage and full boll openning stage, root biomass weresignificantly lower, but the aboveground biomass, bud and boll biomass and seed yield wereall significantly higher than the control. At the treatment of root restriction cooperatingmoderate water and nitrogen supply, the aboveground biomass, bud and boll biomass weresignificantly increased. Consequently, the boll number per plant, single boll weight and seedyield were all significantly higher than other treatments. Under the condition of root domainvolume limited, optimizing the water and nitrogen supply at growth stages, can improve leafphotosynthetic performance, increase dry matter accumulation aboveground and allocationproportion to the reproductive organs.4. Influence of different water and nitrogen supply on root morphological characteristicsof cotton under different irrigating depth was studied. In the0-40cm soil layer, RVD, RMD,RAI and RLD were in the order of CK（drip irrigation on the soil surface）> H₀（irrigationdepth was20cm underground）> H₁（irrigation depth was40cm underground）. While in the40-80cm and80-120cm soil layers, the above parameters were shown as CK <H₀<H₁. Waterand nitrogen supply significantly （P <0.05） decreased root quality. Among different waterand nitrogen treatments, all the root morphological parameters, root biomass and Root-shootratio all performed W₀N₀> W₁N₀> W₀N₁> W₁N₁. In upper soil layer （0-40cm soil layer）,root quality was reduced with the increase of the irrigation depth and the supply of water andnitrogen, and the depth of the irrigation was the main effect factor. In the soil layers underirrigation depth, the water and nitrogen supply became the main factor to reduce root amount.5. Influence of different water and nitrogen supply on root physiological characteristicsof cotton under different irrigating depth was studied. At different irrigating depths, rootantioxidant protective enzymes （SOD, POD and CAT） activity in each soil layer were shownas H₀> CK> H₁. At the different supply of water and nitrogen, root protective enzymesactivity performed W₁N₁> W₀N₁> W₁N₀> W₀N₀. This showed that shallow undergrounddrip irrigation and the supply of water and nitrogen were beneficial to improve the rootantioxidant activity of protective enzyme system, postpone root senescence on the whole.Water and nitrogen supply was the main effect factor to determine the root protective enzymesactivity. At the treatment of moderate water and nitrogen supply （W₁N₁） cooperating withirrigation depth20cm underground （H₀）, root protective enzymes activity was the highest.6. Influence of different water and nitrogen supply on leaf physiological characteristics and yield of cotton under different irrigating depth was studied. The response of leafantioxidant protective enzymes （SOD, POD and CAT） activity, leaf gas exchangeparameters（Pn, Gs）, and chlorophyll fluorescence parameters （Fv/Fm, Φ PS Ⅱ, qP） toirrigation depth, interaction among irrigation depth and water and nitrogen supply were allconsistent with root protective enzymes activity. Among all treatments, aboveground biomassof plant and yield were consistent with Pn, but the performance of root biomass androot-shoot ratio is on the contrary. This showed that shallow irrigation undergroun withappropriate water and nitrogen management is advantageous to the coordination of the growthaboveground and underground of cotton plant, alleviate the contradiction between vegetativegrowth and reproductive growth, to achieve optimization in resource.7. Using the cotton under-mulch-drip irrigation in the field in large scale as experimentalmaterial, the change of root system growth and development in the fields with different yieldlevels was studied. With the increase of yield levels, the total soil RLD, RAI, RVD and RMDdecreased; root and leaf antioxidant protective enzymes （SOD, POD and CAT） and nitratereductase （NR） activity increased. While the root-shoot ratio and root biomass reduced,aboveground biomass, yield and its components increased with the increase of yield levels. Incotton production with higher levels of yield, both the decrease of root-shoot ratio and theincrease of root physiological activity promoted the growth aboveground, optimized the yieldstructure and components, increased production eventually.Through the comprehensive analysis of the root morphological and physiologicalcharacteristics and the relationship with aboveground biomass and yield of cotton, theconclusion was drawn that in the condition of under-mulch-drip irrigation in arid areas, highaboveground biomass was necessary to improve the cotton yield level, but great root growthwas not necessary, root moderately shrinking reduced root redundancy. According to theresults from this paper, the root-shoot ratio of0.21-0.32of cotton in the field is optimum.Through the regulation of water and fertilizer under-mulch-drip irrigation to control the sizeof root system, increase root physiological activity （SOD, POD, CAT and NR） can be used asthe main direction of high yield cultivation and the selection indicators of root morphologyand physiology in genetic improvement of cotton varieties.更多还原