Study On The Effects Of Allelopathy In Sod-culture System Of Citrus Orchard

The production of citrus in our country develops very rapidly. Its yield occupies the third place in the world, but the problems of low production per plant, low quality and low efficiency have not been solved for a long time. The reasons for it are various. It is closely related to the barren of soil, the eficiency of fertilizer and the ignorance of effective management in orchard. The basic reason is that the low soil fertility limits the effects of various cultivating techniques and measures. Sod-culture is the effective way to solve this problem.It is already known that the AM (Arbuscular Mycorrhiza, AM) plays a key role in promoting the growth of plants, the absorption of nutrients, nutrient cycling in the ecosystem and protecting host plants against environmental stress. It is proved that the growth of citrus heavily relies on AMF (Arbuscular Mycorrhizal Fungi, AMF). The utilization of AMF in the production of citrus in our country can efficiently decrease the cost of production, increase the quality of fruits, improve the chemical quality of soil and increase the utilization of fertilizer to optimize citrus industry of our country.In order to protect entironment, cultivate with saved-labor and produce fruits without social effects of pollution, the countries in the world widely use sod-culture cultivation in the orchard cultivation system and do a series of researches. However, these researches focus on the environmental control of orchard ecosystem. Allelopathy universally exists in the nature. It is rarely reported on the application of allelopathy to the selection of the proper intercrop and plant pattern to fully utilize beneficial allelopathy to combine the environmental control and biological control in orchard ecosystem. It must be considered the problem of how to utilize the beneficial allelopathy between plants and between plants and microorganism to remove harmful allelopathy. Aimed at the problems above, these experiments were carried out from allelopathy.Experiment 1 Study on the intercrop effects of different grass speciesBy potted plant experiments, the effects of intercrops (Trifolium repen L., Lotus corniculatus L. and Lolium perenne L. )on the growth of Poncirus trifoliata Raf. seedling and the formation of its AM were studied to screen the best grass species proper to citrus orchard cultivation.It was discovered that inoculate AMF could greatly enhance Poncirus trifoliata Raf. seedling nutrient absorption of minerals, such as P, K,ect., and promote the activity of phosphatase of root system of Poncirus trifoliata Raf. seedling, the absorption and accumulation of the products of photosynthesis as protein and sugar, the enzymatic activities of membrane protection system (SOD, POD, CAT), which remarkably promoted the growth of Poncirus trifoliata Raf. seedling. Sod-culture could increase the reproduce density of AMF and the formation of AM, which promoted the growth of Poncirus trifoliata Raf. seedling indirectly.The cultivation of Trifolium repen L. and Lotus corniculatus L. could notably increase Poncirus trifoliata Raf. seedling nutrient absorption of minerals, as N, P, K, promote the activity of the root system of Poncirus trifoliata Raf.seedling, the absorption and accumulation of the products of photosynthesis, the activity of membrane protective system and promote the growth of Poncirus trifoliata Rafseedling. However, the cultivation of Lolium perenne L.had no noticeable promoting effects and even showed certain restraining effects. The cultivation of Trifolium repen L. .. Lolium perenne L. and Lotus corniculatus L. could greatly increase the number of AMF spores and the length of hyphae in soil and promote the formation of Poncirus trifoliata Rafseedling AM to increase the growth ofPoncirus trifoliata Rafseedling.By comparison of Poncirus trifoliata Raf. seedling's mineral nutrition, activity of root system, the products of photosynthesis, the activity of membrane protective system and the way of growth and the comparison of the promoting effects of the formation of Poncirus trifoliata Rafseedling AM of Trifolium repen L., Lotus corniculatus L. and Lolium perenne L., it was concluded that Trifolium repen Lwas the best orchard grass species proper to citrus orchard.Experiment 2 Study on effects of extracts of the proper intercrop on the growth of Poncirus trifoliata Rail seedling in vitroApplying the aqueous extracts and the 80% methanol extracts of Trifolium repen L. into MS culture medium, research on the the effects of extracts of Trifolium repen L. on the growth of Poncirus trifoliata Raf.seedling in vitro was conducted. The results showed the aqueous extracts of Trifolium repen L. at the volume of 0.5ml, 1 ml and 1.5ml could notably promote the growth of...