【作者】 周丽莉；

【导师】 李隆；

【作者基本信息】 中国农业大学 ， 植物营养学， 2005， 硕士

【摘要】 近年来,随着水土资源的不断减少和人口的日益增长,粮食产量和需求量之间的缺口正逐渐扩大,解决人类粮食安全问题越来越迫切。间作具有充分利用资源和大幅度提高产量的特点,对解决人口持续增长与耕地不断减少之间的矛盾具有重要的现实意义。磷作为不可再生资源,磷矿资源非常有限,如何充分挖掘土壤中的磷素来提高作物的磷利用效率越来越受到世界各国科学家的广泛关注。本研究在课题组前人研究的基础上,利用水培条件下去离子水收集根分泌物,土培条件下滤纸片原位收集根尖分泌物和滤纸培养条件下琼脂显色-质子定量化技术,从作物根系质子分泌和低分子量有机酸的分泌来研究蚕豆/玉米和大豆/玉米两种间作体系作物活化吸收利用土壤中的无机磷的种间促进作用机制,为间作套种的高产高效种植方式提供科学的理论依据,同时也为农业的可持续发展提供有力的保证。获得的主要结果如下: 1.水培条件下,蚕豆、大豆和玉米根系有机酸分泌种类和数量明显不同。蚕豆根系分泌大量的酒石酸和丁二酸。蚕豆有机酸分泌总量在磷处理9天和15天分别是大豆分泌总量的70.8倍和28.5倍,是玉米分泌总量的65.6倍和28.5倍。土培条件下没有发现三种作物根系有机酸分泌的差异。 2.无论是水培条件还是土培条件下,磷水平对三种作物根系有机酸分泌总量没有显著影响。对于水培间作系统,在缺磷9天时,蚕豆/玉米间作根系有机酸分泌总量显著高于大豆/玉米间作;在缺磷15天时,二者没有显著差异。 3.蚕豆有很强的根际酸化能力。在水培实验预处理的前四天,单作蚕豆营养液pH下降到4.4。在缺磷条件下,单作蚕豆营养液的pH在生长的22天内始终低于最初的营养液pH6.0,其中在第4天到第19天,pH基本维持在4.0-4.5之间。在根际显色实验中,蚕豆根系表现出明亮的黄色,根际质子释放量显著高于大豆和玉米。 4.大豆无论在供磷还是不供磷条件下都维持一个较高的营养液pH。根际显色实验中,大豆根系表现出微弱的黄色,且根尖处表现出紫色(碱化)。玉米的根际pH则表现出碱化,水培实验中玉米在缺磷处理的后期营养液pH显著下降。 5.在水培实验间作系统中,无论是供磷还是不供磷,在生长前期约13天以前,蚕豆/玉米间作系统营养液pH始终低于大豆/玉米间作系统。更多还原

【Abstract】 In recent years, gap between crop production and food demands were enlarging, and it became more and more important to raise crop productivity in order to meet the increasing food requirements of an increasing population, with decreasing water and land resources. Intercropping could use resources more effectively and had higher productivity, compared to sole crops. Phosphorus was a kind of unrenewable resources, and very limited in the world. Previous studies showed that P was utilized by intercropping more efficiently than sole cropping systems. However, the mechanism behind it was not clear. So hydroponic culture, technique of different root barriers and paper liter culture were carried out to study the organic acids and proton efflux of roots of faba bean, soybean and maize to illuminate the mechanism of interspecific facilitation on P uptake in fababean/maize and soybean/maize intercropping systems. The objective of the research work was to give scientific evidences for improving productivity and efficient P utilization in intercropping system and give the strong guarantee for agricultural sustainable development. The following results were obtained in experiments.1. In a pot experiment with hydroponic culture, the amount of organic acid exudates from roots was considerably different between faba bean, soybean and maize. Large amounts of tartaric and succinic were exuded from faba bean roots. Total amounts of organic acid exudation of faba bean was 70.8 and 28.5 times as much as that from soybean roots under 9 days and 15days, respectively, and 65.6 and 28.5 times as much as that from maize roots. There was no difference between three plants in soil condition.2. Organic acid exudation for all three species was not affected by P supply level in both pot experiments with hydroponic or soil culture. In hydroponic culture, the total amounts of organic acid in faba bean/maize intercropping was significantly higher than soybean/maize intercropping at 9 days of P deficiency; there was no significant difference between two intercropping patterns under 15 days of P deficiency.3. Faba bean had strong ability of rhizosphere acidification. At very early growth stage, plants were grown in half concentration of full nutrient solution, which supplied with 0.1mM L-1 P, the pH of nutrient solution grown faba bean only for four days was decreased to 4.4. Under P deficiency, the pH of the nutrient solution grown faba bean was lower than initial 6.0 during the whole cultivated growth states, and stabilized 4.0-4.5 from day 4 to day 19. In visualization of rhizosphere acidification, faba bean rhizosphere turned bright yellow, and the amount of proton efflux of the faba bean was significantly greater than soybean and maize.4. In hydroponic culture, the pH of the solution grown soybean was always higher than initial 6.0 of new nutrient solution, even under P deficiency condition. In visualization of rhizosphere acidification, soybean presented a rhizosphere acidification too, but was much less than faba bean. Furthermore, soybean seems to alkalize its rhizosphere in root tips whatever P was supplied or not. In contrast, the whole roots of maize alkalized the rhizosphere in both monoculture and intercropping, regardless supplying with P or not. In hydroponic culture, the pH in the solution grown maize was declined onlyafter P deficiency for 13 days.5. In hydroponic culture, the pH of nutrient solution grown faba bean and maize together in the same pot (intercropping of faba bean and maize) was lower than that of intercropping of soybean and maize during early (about 13 days) growth stage, regardless of P supply or not.更多还原