Root Contribution in Controlling Vegetative and Reproductive Growth in Citrus Growing

通过3年的试验，研究了根系对柑桔营养生长和生殖生长的调控作用。Inoue和Kataoka阐明，在塑料绿色温室生长条件下，低于25℃的低温是启动花芽分化所必需的。Yamashita指出激动素对根的生长有重要作用。长谷川注意到，在整个10月至2月期间，碳水化合物的积累是活跃的'Tosabuntan'柚根。石井和角谷从低投入可持续农业的角度在柑橘种植中进行了实验。结果表明：（1）禾本科和豆科杂草中VAM真菌的侵染率较高。(2)生草栽培能有效提高VAM真菌在柑橘根部的侵染率。(3)长期施用磷肥导致土壤中残留的PO 43-超过50 ppm，导致根系VAM感染率较低。(4)柑橘渣提取物的25%MeOH洗脱液含有对VAM真菌的刺激物质。此外，将25%MeOH洗脱液施用于土壤对刺激VAM真菌活性非常有效。(5)从洗脱液中分离出三种化合物。其中两种被鉴定为橙皮苷和橙皮苷。这些化合物对珍珠巨孢霉菌丝生长有促进作用。(6)可以强调的是，VAM真菌在土壤中的增殖将是促进低投入可持续农业的首要问题。

For 3 years, our experiments were carried out to evaluate the root contribution in controlling vegetative and reproductive growth of citrus trees. Inoue and Kataoka clarified that low temperatures below 25℃ are necessary to initiate flower bud initiation under plastic green house growing conditions. Yamashita pointed out kinetin has a significant role for root growth. Hasegawa noticed that throughout the period from October to February carbohydrate accumulation was active in the roots of 'Tosabuntan' pomelo. Ishii and Kadoya carried out experiments from the view pint of Low Input Sustainable Agriculture in citrus growing. The results are as follows ; (1) Infection of VAM fungi was high in gramineous and leguminous weeds. (2) Sod culture system with those plants was effective to increase infection percentage of VAM fungi in citrus roots. (3) Prolonged use of phosphorous fertilizer resulting in over 50ppm of residual PO43- in the soil caused low VAM infection in the roots. (4) 25% MeOH eluates of citrus juice pomace extracts contain stimulatory substances for VAM fungi. Further the application of the 25%MeOH eluates to the soil is very effective in stimulating VAM fungi activity. (5) Three kinds of compounds were isolated from the eluates. Two of them are identified as hesperidin and narirutin. Those cocompounds stimulated the hyphal growth of Gigaspora margarita. (6) It can be stressed that VAM fungi proliferation in the soil will be the primary importance for the promotion of Low Input Sustainable Agriculutre.