【作者】 牛俊义；

【导师】 胡恒觉； 黄高宝；

【作者基本信息】 甘肃农业大学 ， 作物栽培学与耕作学， 2002， 博士

【摘要】 通过3个生长季的大田试验和管栽模拟试验，研究了陇中半干旱地区地膜栽培春小麦根系生长的时空分布规律、干物质累积分配规律及根冠关系、叶片提前枯黄衰老的原因及施氮对叶片衰老的影响。所取得的主要研究结果有： (1)地膜覆盖有利于促进春小麦根系的早生快发，有利于增加根干重。拔节前是地膜春小麦根系伸长速率最快的时期，日增长量比露地春小麦高1.34cm/株·d～1.24cm/株·d。地膜春小麦的根干重始终高于露地，且根干重日增长高峰期比露地春小麦早出现15d左右。施氮对地膜春小麦根系生长的促进作用是速效、短期的。任何时期施氮都有利于地膜春小麦根干重的增加；中后期追施氮肥，可增加根系的总根长。根长和根干重的垂直层次分布结构，可用多项式y=a+bx+cx~2+dx~3 描述。 (2)覆膜对春小麦吸氮量、特殊吸氮率(SARN)、特殊吸磷率(SARP)的影响是显著的。地膜和露地春小麦比较，吸氮量增加33.20％，SARN平均值提高16.82％，SARP平均值提高6.47％。不同时期追施氮肥，对地膜春小麦氮效率的影响是不同的。分蘖期追施氮肥，氮肥利用效率和生理效率最高；拔节期追施氮肥，氮肥利用率和农学效率最高；孕穗期追施氮肥，氮效率最低。 (3)覆膜有利于协调春小麦根冠间的干物质分配关系，根冠总生物量显著高于露地小麦。地膜春小麦前期根系的早生快发，促进了地上茎叶的生长，使根冠比降低18.87％；中后期茎叶生物量的显著增加，促进了地下根系重量的增加，使根冠比增高1.42％～7.34％；相对发达的根系保证了作物吸收器官(根)和失水器官(叶)之间的平衡，协调了根冠间的干物质分配关系，提高了光合产物在繁殖器官中的分配比例，使春小麦的穗粒重比露地小麦增加27.61％。对地膜春小麦而言，早期施氮有利于促进茎叶生长，降低根冠比；中期施氮有利于促进根系增粗，增加根冠比。 （4）地膜春小麦前期叶面积的增长快，后期进入光合积累的时间早， 净同化率高，且快速生长持续期长。地膜和露地春小麦比较，单株最大叶面 积增加 17．16％，最大绿叶面积峰值早出现6d，开花前干物质积累量高8．97％。 前期叶面积的增长，为后期干物质积累奠定了良好的基础。拔节期追施氮肥 能有效地增加地膜小麦的单株叶面积和干物质生产量。追肥和不追肥处理比 较，单株叶面积增加 15．03％～31．11兄 地上干物重增加 3．7％～41．66兄 （5）地膜春小麦具有较高的相对生长速率，尤其开花后0～7d的相对生 长速率比露地小麦高8．20％～13．92％，因而开花后于物质积累量、日生产量 明显高于露地春小麦。在积累高峰期至开花后15～21d单茎、群体于物质 积累量、日生产量分别高出露地春小麦18．19％～22．01％和46．04％～48．27％。 （6）地膜春小麦茎、叶、颖壳和穗轴的输出率、分配率、转换率均高 于露地春小麦。尤其茎秆营养物质向籽粒的移动量大，转换率高。地膜春小 麦叶片、茎秆、颖壳穗轴的输出率分别比露地春小麦高3．23％～3石7％、 3．53％～4．55％和1．80％～3石3％：转换率分别比高0．12％～o．46％、0．92％～ l．90％和 0．35％～0．87％；各非经济器官输出的干物质对籽粒干物质的贡献率 比露地春小麦高1．9％～2厂％。地膜春小麦籽粒起始生长势、最大生长速率、 活跃生长期均高于露地春小麦。而达最大生长速率的天数短于露地小麦。说 明地膜春小麦籽粒灌浆期具有较强的生长势，灌浆速率快，灌浆时间长，最 终表现为粒重高、产量增加 36％。 门）地膜春小麦前期叶片叶绿素、可溶性蛋白质含量增速快，膜脂过氧 化水平低，叶绿素和蛋白质含量分别比露地春小麦高 17．26％～31．49％和 5．53％～7．96％；叶片丙二醛含量和电导率分别比露地春小麦低 15名2％～ 19刀2％和 9．79％～12刀9％。开花灌浆后地膜春小麦叶绿素、蛋白质降解速度 增加，膜脂过氧化程度增强，叶片叶绿素、蛋白质含量降低，丙二醛含量升 高，细胞膜透性增大，叶片衰老速度加快。但和露地春小麦比较，地膜春小 麦叶片的衰老并没有对其产量的增加造成多大影响，成熟期穗粒重仍比露地 2 春小麦增加 27石1％。说明地膜春小麦叶片的衰老并非早衰，而是作物生命 活动的正常终止。 中后期施氮能显著提高地膜春小麦叶片叶绿素和可溶性蛋白质含量，降 低MDA含量，抑制叶片电导率的升高。因而能延缓地膜春小麦后期叶片衰 老和光合功能的衰退，延长叶片功能期。 （8）各叶片衰老参数、光合速率及粒重之间有密切的相关关系。叶绿素 含量是调控叶片衰老极其重要的一个指标，其含量的高低抉定了叶片更多还原

【Abstract】 By the field experiment and simulated experiment of tube cultivation within three growth years, the temporal and spatial distribution of roots, dry matter accumulation and allocation, relation between roots and canopy of spring wheat mulched with plastic film in semi-arid area, middle of Gansu, and the reason of leaves turned yellow in advance, effect of nitrogen application on the leaves senescence are studied in this paper. The main results are as following:1. Film mulch is favorable to earlier growth and faster development, and increase dry matter weight of roots of spring wheat. Daily growth rate of roots of spring wheat mulched with plastic film was higher 1.34~1.24cm/plant.d than that of spring wheat no mulched with plastic film during pre-jointing period, which is the fast period of roots extension. Dry matter weight of roots of spring wheat with film mulched was higher than that of the contrast spring wheat from beginning to end. Furthermore, the peak period of daily growth of the former was earlier 15d than that of the later. Effect of nitrogenous application on roots growth of the former was quick-acting and short-term. Nitrogen application was favorable to increase of dry roots weight at any stage of spring wheat development. Supplement nitrogen application during the middle and posterior period of spring wheat can increase the whole roots length. Distribution of length and dry weight of roots along profile of soil could be expressed as multinomial y=a+bx+cx2+dx3.2. Effect of the film mulch on the amount of absorption nitrogen, special absorption rate of nitrogen (SARN) and special absorption rate of phosphorus (SARP) was significant. Compared with no mulched wheat, the film mulched wheat was higher 33.20%, 1 6.28% and 6.47% in amount of absorption nitrogen, average SARN and SARP, respectively. Supplement nitrogen application at different wheat development had a different effect on nitrogenous efficiency of spring wheat mulched with film. As supplement nitrogen application at tillering stage, nitrogen use efficiency and the physiological efficiency were the highest. As supplement at jointing stage, nitrogen use rate and agronomic efficiency were the highest. As supplement nitrogen application at booting stage, nitrogen efficiency was the lowest.3. Film mulch was favorable to regulating dry matter allocation between root and crown of spring wheat. The whole biomass of the root-crown of spring wheat mulched with film was obviously higher than that of the spring wheat no mulched with film. Early growth and quick development of the former roots at earlier stage improved the growth of shoot-leave aboveground, which caused the ratio of root to crown decrease 18.87%. An obvious increase of shoot-leave biomass at the middle and posterior stage improved the increase of roots underground, which caused ratio of root to crown increase 1.42~7.34%. Relatively developed roots guaranteed the equilibrium between absorption organ (root) and loss water organ (leave) of crop, coordinated dry matter allocation between root and crown, and improved allocation rate of photosynthetic production in propagation organ. Therefore, grain weight of per spike of spring wheat mulched with film was higher 27.61% than that of the contrast. Nitrogen application at earlier stage for the film-mulched wheat was favorable to improve the growth of shoot and leaves, and decrease the ratio of root to crown. At middle stage, nitrogen application for wheat mulched with film was favorable to roots becoming thick and the ratio of root to crown getting increase.4. Leaf area of the film mulched wheat at earlier stage grew faster, and photosynthetic accumulation was earlier at later stage, net assimilation rate was higher, the continued period of the fast growth was longer. Compared with wheat with no mulched, the largest leaf area of a single plant of film mulched wheat increase 17.16%, the peak value of the largest green leaf area appeared 6d earlier, dry matter accumulation rate was higher 8.97% before anthesis. Increase of更多还原