【作者】 徐强；

【导师】 程智慧；

【作者基本信息】 西北农林科技大学 ， 蔬菜学， 2007， 博士

【摘要】 套作是我国农民在长期生产实践中,逐步认识和掌握的一项耕作措施,选择合适作物种类进行套作,可提高作物的水、肥、光资源的利用效率,大幅度增加产量。线辣椒是我国农产品出口创汇的名优特产,主要以套作模式进行栽培,获得了明显的套作产量优势,因此越来越受到农学家和生态学家的关注。本论文通过盆栽和大田的单作和套作种植、种间根系分隔技术,系统研究了线辣椒/玉米套作复合群体内作物的生长发育、光合特性、作物群体的光截获和利用效率、作物干物质积累规律、作物养分吸收与利用效率、根际土壤微生物多样性、根际、非根际土壤酶活性及有效养分含量等生理生态机制,为提高套作体系生产力和资源利用效率提供科学依据。本论文研究主要获得以下结果。线辣椒/玉米套作不仅改变了复合群体内光的分布,也使线辣椒和玉米功能叶片的Chla、Chlb和Chla + Chlb含量明显提高。与单作种植的玉米、线辣椒相比,套作明显降低了它们功能叶的叶绿素含量随生育期的递减速率。线辣椒/玉米套作提高了玉米晴天和阴天的单叶最大净光合速率,提高幅度分别为20.6%、47.13%;但套作降低了线辣椒单叶最大净光合速率,尤其在阴天更明显,达55.65%。线辣椒/玉米套作有利于提高线辣椒的日平均光能利用率。PAR对线辣椒不同时期的光合作用的影响不一样,不同的生育期内两者具有不同的线性关系。套作种植的玉米、线辣椒的平均株高均分别大于单作种植玉米、线辣椒。与单作玉米相比,套作玉米的根体积、根表面积、根的平均直径、根尖数和根交叉数都有一定程度的提高。套作玉米的根冠比大于单作玉米,增加了37.77%。与单作线辣椒相比,套作线辣椒的根系形态指标有弱化趋势。套作提高了线辣椒的根冠比。套作使玉米和线辣椒的根系活力均有增加,线辣椒增加的幅度大于玉米。全生育期内线辣椒/玉米套作群体平均叶面积指数比单作线辣椒提高22.47%,比单作玉米减少2.46%。线辣椒/玉米套作使群体LAI≥3的日数分别比单作线辣椒、单作玉米提高1.13倍和19.32%。线辣椒/玉米套作具有明显的套作产量优势,生物学LER为1.29,经济产品产量LER为1.33,均大于1,但以经济产品产量的套作优势更明显。线辣椒/玉米套作模式中经济产品产量和生物学产量的套作优势来自于地上部种间相互作用和地下部种间相互作用两个方面,但主要来自地上部贡献,其相对贡献以地上部占75%、地下部占25%。线辣椒/玉米套作种植时,其粒(果)数/叶比、粒(果)重/叶比均高于单作种植。线辣椒/玉米套作群体PRA捕获效率高于单作种植的线辣椒、玉米。套作群体PRA截获效率比按套作比例对单作作物PRA截获效率加权平均值高46.5%。套作群体光能利用效率比按套作比例对单作作物的光能利用效率加权平均值下降了11.7%。线辣椒/玉米套作群体的产量优势是由于套作后光截获效率提高而非光能利用效率的提高所致。套作线辣椒地上部干物质积累速率与单作线辣椒相比,前者的速率绝对值大于后者;但其相对速率较低;套作玉米的干物质积累速率远大于单作玉米。套作群体中的线辣椒植株干物质向茎、枝的分配比例明显低于单作,而向果实、根的分配比例高于单作,向根的分配比例比单作高2.6%。套作玉米植株的干物质向各器官的最终分配比例与单作差异不显著,套作对玉米植株干物质在器官间的分配影响较小。套作使玉米植株干物质向茎的分配比例下降,根的分配比例增加。套作玉米植株的氮、磷吸收量在整个生育期均明显的高于单作。与玉米共生期间,线辣椒植株的氮、磷吸收受到限制,但玉米收获后,线辣椒植株有显著的氮、磷吸收恢复现象,最后套作线辣椒植株的氮、磷吸收量达到或超过单作种植。施氮肥降低了玉米相对线辣椒的氮、磷营养的竞争比率。套作对玉米、线辣椒植株的钾吸收量的影响不明显。套作群体中线辣椒对氮、磷营养竞争表现出一定的边行劣势,而对钾营养的竞争没有表现出明显的边行劣势。盆栽和大田试验结果都显示,与单作相比,套作能明显促进作物对氮、磷、钾的吸收量;施氮肥后,套作相对单作的养分吸收量增加的幅度减小。套作群体的氮、磷、钾的利用效率低于单作。整个生育期内,套作种植的线辣椒、玉米根际土壤中细菌、真菌、放线菌的数量均比单作多,套作体系中具有显著的套作根际效应。套作使作物根际土壤微生物生物量碳、氮含量也高于单作。套作体系中作物根际土壤微生物群落的AWCD值、Simpson多样性指数、Shannon多样性指数、种间相遇几率(Pie)、Alatalo均匀度均高于单作,作物的生物学产量与这些土壤微生物的多样性指数之间存在明显的正相关,且在一些生育期显著相关,说明土壤微生物的多样性对植物生长的存在显著的影响。套作种植的线辣椒、玉米根际与非根际土壤微生物数量、酶活性、有效养分含量均高于单作种植,体现了套作优势的土壤微生态机制。作物根际土壤的有效养分含量均低于非根际。土壤微生物主要类群数量是影响土壤酶活性主要因子,与土壤酶活性显著相关。有机质、碱解氮含量与土壤酶活性、微生物数量呈极显著相关,有效磷含量与土壤酶活性、微生物数量呈正相关。土壤真菌数量、脲酶活性与有效钾含量呈负相关。通径分析表明,促进有机质积存的主要生物因素是脲酶、过氧化氢酶、细菌、蛋白酶,蔗糖酶是影响碱解氮的最主要因子,脲酶是影响有效磷的最主要因子,细菌是影响有效钾的最主要因子,碱性磷酸酶、真菌只是选择性地对有机质的积存和氮、磷、钾有效养分的形成起作用。放线菌对土壤养分的直接作用系数为负,对土壤养分形成的作用较小。更多还原

【Abstract】 Relay intercropping is a commonly used agronomic practice in China for many years. Suitable crop relay intercropping pattern can use nutrient, water and solar radiation resources efficiently and enhance crop yield enormously. Capsicum (Capsicum.annuum L.) is a unique export-oriented agriculture product in China, which is mostly planted by relay intercropping pattern and has achieved significant relay intercropping yield advantage. Therefore, capsicum relay intercropping pattern is attracting more and more agronomists′and ecologists′attention. In this paper, physiology and ecology mechanisms of capsicum/maize (Zea mays L.) relay intercropping system were studied by the way of pot culture experiments, field growth experiments and different interspecific root barriers technique. The objective of the work is to give scientific evidence for improving productivity and higher efficient resource utilization in relay intercropping system. The following main results were obtained in the experiments.Capsicum/maize relay intercropping not only altered solar radiation distribution in crop population, but also enhanced chlorophyll a and chlorophyll b content of capsicum and maize function leaves markedly. Compared to monoculture maize and capsicum, Capsicum/maize relay intercropping depressed the descending rate of function leaves chlorophyll content in the process of leaves senescence. Capsicum/maize relay intercropping improved the maximum net phointercropping reduced the maximum net photosynthesis rate of sloe growth capsicum leaf, especially in cloudy, reduced by 55.65%. In this relay intercropping system, diurnal average photo use efficiency of capsicum was enhanced. There was a different linear relationship between photosynthetic active radiation and photosynthesis in the different capsicum growth stage.The average height of relay-intercropped maize and capsicum plant respectively exceeded that of monoculture maize and monoculture capsicum. Compared to monoculture maize, the volume, surface area, average diameter, tip number and chiasma number of relay-intercropped maize were improved. Root top ratio of relay-intercropped maize was increased by 37.77% as compare with monoculture. Morphological configuration characteristic of relay-intercropped capsicum took on weak current and root top ratio increasing as compare with monoculture capsicum. The root activity of relay intercropping components was enhanced in capsicum/maize relay intercropping system, and the increase extent of capsicum root activity exceeded that of maize root activity.In the whole grow stage, average LAI (leaf area index) of capsicum/maize relay intercropping system increased by 22.47% as compared with monoculture capsicum; reduced by 2.46% as compared with monoculture maize. The number of day, which LAI of capsicum/maize relay intercropping system exceeded 3, increased by 1.33 times as compared with monoculture capsicum; increased by 19.32% as compared with monoculture maize. There was a marked relay intercropping yield advantage in the capsicum/maize relay intercropping system, LER (Land equivalent ratio) of biological yield was equal to 1.29, and LER of economy production yield was equal to 1.33, economy production yield advantage more significant than biological yield advantage. Economy production yield and biomass yield advantage of capsicum/maize relay intercropping system not only resulted from crop interspecific interaction of above-ground but also below-ground interspecific root interaction, and furthermore, relative contribution of above-ground accounted for 75% and relative contribution of below-ground accounted for 25%.Grain (fruit) number to leaves number ratio and grain (fruit) weight to leaves number ratio of capsicum and maize crop in relay intercropping system exceeded those of monoculture capsicum and maize completely. Compared to monoculture capsicum and maize, there was a bigger PRA interception efficient in capsicum/maize relay intercropping system. PRA interception efficient of capsicum/maize relay intercropping system raised by 46.5% as compared with the weight average of PRA interception efficient of monoculture crop according to relay intercropping growth proportion. Photo-energy utilization efficiency of capsicum/maize relay intercropping system reduced by 11.7% as compared with the weight average of Photo-energy utilization efficiency of monoculture crop according to relay intercropping growth proportion. The yield advantage of capsicum/maize relay intercropping system resulted from the increase of PRA interception efficient, not from the increase of Photo-energy utilization efficiency. Shoot dry matter accumulation rate of relay-intercropped capsicum had bigger absolute value of rate, and smaller relation rate as compared with that of monoculture capsicum. The shoot dry matter accumulation rate of relay-intercropped maize exceeded far it or monoculture maize.The proportion, which relay-intercropped capsicum plant dry matter was allocated to stem and branch, was smaller, and which relay-intercropped capsicum plant dry matter was allocated to fruit and root, was bigger, as compared with those of monoculture capsicum. The proportion of relay-intercropped capsicum plant dry matter was allocated to root increase by 2.6% as compared with it of monoculture capsicum. Dry matter allocation proportion of different organ of maize plant had no distinct difference between relay-intercropped maize and monoculture. Compared to that of monoculture maize, the dry matter allocation proportion of stem of intercropped maize was reduced; however it increased in root of intercropped maize.In the whole grow stage, nitrogen (N), phosphorus (P) absorption quantity of relay-intercropped maize were always more than those of monoculture maize. During the symbiosis of maize and capsicum, N, P absorption of capsicum were inhibited, however, N, P absorption quantity of relay-intercropped capsicum plant showed marked recovery phenomena after maize harvest, finally N, P absorption quantity of relay-intercropped capsicum were attained or exceeded N, P absorption quantity of monoculture capsicum. N, P nutrition competition ratio of relay-intercropped maize relative to relay-intercropped capsicum decreased after application of N fertilizer. Relay intercropping growth pattern almost did not influence potassium (K) absorption of relay-intercropped capsicum and maize, compared to monoculture capsicum and maize. N, P nutrition absorption of capsicum showed side row disadvantage in capsicum/maize relay intercropping system. However, these phenomena did not happen in the K nutrition absorption of relay-intercropped capsicum. The result of pot culture and field culture experiments showed, relay intercropping growth pattern improved N, P, K nutrition absorption quantity of relay intercropping crop as compared with monoculture, the increase extent of relay intercropping crop nutrition relative to monoculture decreased after application of N fertilizer. Use efficient of N, P and K nutrition in the capsicum/maize relay intercropping system was less than monoculture.Bacteria, fungi and actinomycete number of rhizosphere and non- rhizosphere soil in the capsicum/maize relay intercropping system were generally more than monoculture capsicum and maize in the whole grow stage, there was a relay intercropping rhizosphere effect in the capsicum/maize relay intercropping system. Microbial biomass carbon and nitrogen content of rhizosphere soil of relay-intercropped crop was more than monoculture crop. Average well color development (AWCD) value, simpson diversity index, shannon diversity index, probability of interspecific encounter (Pie) and alatalo evenness of relay-intercropped crop were all more than these diversity indexes of monoculture. There was a positive correlation or significantly positive correlation between crop biological yield and these diversity indexes, this suggested that soil microbial diversity might play an important role in the process of crop growth.Microbial number, enzyme activity and effective nutrition content of rhizosphere and non-rhizosphere of relay-intercropped maize and capsicum were all more than monoculture, this indicated soil micro ecology mechanism of relay intercropping advantage. Rhizosphere soil effective nutrition content of crop was less than non-rhizosphere soil effective nutrition content of crop. Soil important microbe group number was main factor influencing soil enzyme activity; as well, there was a significant correlation between them (p<0.01). The content of organic matter and alkali-hydrolyzable nitrogen were also significantly correlated with soil microbe number and enzyme activity (p<0.01), available phosphor content was positively correlated with soil microbe number and enzyme activity. Soil fungi number and urease activity were negatively correlated with soil available potassium content. After the pathway analysis was done between soil nutrients content and biological factors, a conclusion was drawn, the urease, catalase, bacteria, protease were the main biological factors of deposit of organic matter; the surcease was the most important factor affecting alkali-hydrolyzable N; the urease was the most important factor affecting available P; the bacteria was the most important factor affecting available K; the alkaline phosphatase and fungi only selectively affected the deposit of organic matter and the forming of available nutrients of N, P and K. The direct path coefficients were negative between actinomycete and soil nutrient, which showed that actinomycete affected soil nutrient slightly.更多还原