Am Fungal Characteristics And Growth Of Research On Citrus

Arbuscular mycorrhiza is a symbiotic association between plant roots and arbuscular mycorrhizal fungi ( AM fungi ) in soil. Plants involved in this association are most of the terricolous plants. The fungi related are classified in six genera of order Glomales, they are Glomus, Sclerocystis, Acaulospora, Entrophospora, Gigaspora and Scutellospora. The typical character of AM fungi is that they are able to develop branch structures like a tree in cortex cells of host roots, called them arbuscules. The importance of AM fungi is their role as a link between plant and soil. They are mediators of nutrient transport from soil to plant and from plant to soil which are crucial components of both plant and soil development and health. So, it is very important to study AM fungi for improving the crop production, crop quality and for reservation of ecologic balance. Because of few root hiars on citrus root surface, citrus growth highly depends on Mycorrhiza. The research and application in mycorrhizal technology will promote the sustainable development of citrus industry. For the purpose of application of mycorrhiza in citrus production, we used in common use stock seedlings of trifoliate orange (Poncirus trjfoliate Ralf.), bearing pomelo trees ( Citrus grandis (L.) Osbeck), Bahia grass ( Paspalum not atum FlUgge.) and a few familiar weeds in citrus orchard as experimental materials, mainly studied in effects of fermented plant organic matters on citrus growth and citrus mycorrhizal formation, in effects of inoculation to fields with AM fungi inocula on the fruit quality of bearing pomelo trees, in heat-resistant and draught-resistant ecophysiologic mechanism of mycorrhizal plants, in AM fungi in vitro culture, in biological characters of AM fungi and in introductions of some good grasses for sod culture in citrus orchard as follows. Experiment 1 Effect of matters from fermented Bahia grass (Paspalum notatum FlUgge) shoots and leaves on the growth and mycorrhizal formation in roots of trifoliate orange (Poncirus trjfoliata Ralf. ) seedlings This experiment was conducted in Prof. Ishii's lab of Ehimei University, Japan during the period from May to September in 1999. After Bahia grass shoots and leaves were fermented perfectly, the 1% (w/w) fermentation liquid and fermented shoots and leaves of Bahia grass were amended respectively into pots in which pot soil contained very high density AM fungi propagula (2600 spores per 50g soil). Non-mycorrhiza trifoliate orange seedlings were planted in these pots. The control pots were amended water only. 70 days later, the measurement results showed that: The heights of trifoliate orange seedlings treated by control, fermentation liquid and fermented shoots and leaves from Bahia grass fermentation respectively were 15.5 - 1.2cm, 20.9 -1.1cm and 28.3 -3.2cm; Root fresh weights were 1.50 -0.2g, 1.90 + 0.2g and 2.20 + 0.3g; Total fresh weight of seedlings were 2.90 + 0.3g. 3.20 + 0.3g and 4.60 f 0.8g. Compared with the control, the seedling heights, fresh root weights and total fresh weights in treatments of fermentation liquid and fermented shoots and leaves of Bahia grass were higher and heavier than in that of controls. That means fermentation maters especially fermented Bahia grass shoots and leaves could stimulate citrus growth significantly. The mycorrhizal infection rate of trifoliate orange seedlings in treatments of control, fermentation liquid and fermented shoots and leaves were 84.08...