190 Weed Research, Japan Vol. 36 (1991)

Weed Research. Japan Vol. 36(2)190～193(1991) 雑 草 研 究 Short Report

Allelopathy of Japanese angelica-

Daiichiro Miyajima*

Key words: Japanese angelica-tree, Allelopathy vestigated. Materials and Methods キ ー ワ ー ド: タ ラ ノ キ, ア レ ロ パ シ ー The study was done on sand at the farm

Introduction of Fukui Prefectural College in 1989. Cab- bage, lettuce, Japanese hornwort, welsh onion, Japanese angelica- ( elata See- garland chrysanthemum, tomato, , man) are that belong to sweetcorn, buckwheat, soybean, kidney bean, . They grow wild and their buds edible burdock, carrot, and taro were used. are eaten as vegetables. While varieties They were cultured in a field subsequent to without thorns are cultured, Japanese angelica- Japanese angelica-tree culture. The trees over trees are obstacles in afforestation. a two year period were removed from the These trees multiply primarily by their field (hereinafter referred to as Experiment) widespreading roots. Weeds and poor growth together with their roots of more than=5 of surrounding crops are factors often obser- mm in diameter on 26 Apr. 1989. There had ved in fields where they exist, indicating been no other crop in this field and weeds probable allelopathy of Japanese angelica- had been removed by hand during the two trees. In this study, effects of these trees on year period. The field had been fertilized the growth of some kinds of crops were in- only in 1987. Five 5X0.9m and 0.1 m high 宮 島大 一 郎: タ ラ ノキ の ア レ ロパ シ ー raised beds were prepared and spaced center *Faculty of Agriculture, Shinshu university, Minami- minowa-mura, Japan to center 1.2m apart on the same day the (Received September 21, 1990) trees were removed. A 16N-13P-14K granular D. Miyajima: Allelopathy of Japanese angelica-tree 191

welsh onion garland chrysanthemum

tomato eggplant

sweetcorn buckwheat

soybean kidney bean

carrot taro

Fig. 1 Growth of crops subsequent to Japanese angelica-tree cultivation O: Control, O: Japanese angelica-tree field 192 Weed Research, Japan Vol. 36 (1991)

fertilizer (150gm-2) and 20MgO-70CaO crop had been cultured in the field and no magnesium lime (50gm-2) were preplant- fertilizer had been applied until the experi- broadcast and incorporated before bedding. ment reported here. The field had occasion- Three beds were divided into 4 plots of 1.25 ally been tilled to abolish weeds. X0.9m each. Crops except cabbage were Results and Discussion seeded in two furrows with 0.5m spacing in each plot on 16 May. After germination, Lettuce, Japanese hornwort, and edible bur- they were thinned as necessary. Cabbage seeds dock seeds did not germinate in the Experi- were sown in a greenhouse on 9 March and ment, while all three grew normally in Con- seedlings were grown by the usual method. trol (data not shown). A entire bed was used for the planting of height of welsh onion, garland chry- taro tubers and another bed was used for santhemum, tomato, eggplant, carrot, and cabbage seedlings. Both crops were planted taro were reduced in Experiment from the in staggered row; between-row plant spacing early growth stage and that of soybean and was 0.5m and within-row plant spacing was kidney bean was reduced from the middle 0.5m. Planting dates of planting of cabbage growth stage on. Plant height of sweetcorn and taro were 26 Apr. and 16 May, respec- and buckwheat were only slightly reduced tively. A 0.05N-0.025P-0.04K liquid fertil- in Experiment (Fig. 1). izer (2lm-2) was applied on 1 Aug.. Height Growth retardation of the Experiment crops of ten arbitrary per crop were mea- was observed at the time of harvest (Table 1), sured. Crops were harvested at suitable times, and indicated the allelopathy of the Japanese and top fresh weight, undergroundpart fresh angelica-tree. Though duration of the effect weight, weight, and head weight were of the allelopathic agent(s) is uncertain, measured. growthh retardation continued for a fairly The same methods were implemented in long period. another field in the farm of Fukui Prefectural Generally, the concentration of fertilizer, College where no Japanese angelica-tree had especially nitrogen, in soil affects plant ever grown (hereinafter referred to as Con- growth. However there was believed to be trol). After a culture of eggplant in 1987, no little difference in the concentration of these

Table 1. Growth of crops subsequent to Japanese angelica-tree cultivation (Figures indicate percentage of Experiment against Control) D. Miyajima: Allelopathy of Japanese angelica-tree 193

substances in the soil between Control and mechanisms of other plants' allelopathic agents Experiment at the beginning of this experi- (3). The mechanisms of the agent (s) of the ment as the soil was sand and no fertilizer Japanese angelica-tree are not yet clear; no had been applied to either plot for more effect of growth promotion was observed. On than a year. The amount of applied basal the other hand, soybeans grown in the field fertilizers was also minimal in order that from which the trees had been removed growth would not be retarded by salt injury. achieved almost equal fruit yield to those in It seems possible that the decreased nitrogen the field where no Japanese angelica-tree had in the soil caused by decomposition of the ever grown, in spite of retardation of the remaining roots of the Japanese angelica-tree former's plant height. This becomes rather influenced the growth of crops in Experiment. an advantage in respect to lodging resistance. But it is difficult to think that this phenom- Though care must be taken in culturing enon was the only reason for the inferior crops following Japanese angelica-tree culture, growth as Japanese angelica-trees do not have allelopathy of this tree is benificial for weed many thin roots and their decomposition is control by revealing sensitive weeds and the slow in dryable sand. Further study is needed duration of its allelopathic effect. on other possible influential factors by apply- ing more basal fertilizers or by increasing Acknowledgements: The author is gra- the number of side dressings. teful to Dr. Misako Ito and Mr. Shinya Many compounds are reported to be allelo- Umemoto for their helpful advice and to Ms. chemics (2). Arbors generally contain phe- Heather Ogawa for her correction of the nolic compounds in their roots. These may English manuscript. also be the cause of allelopathy in this case.

Saponin containd in Japanese angelica-trees is References one of the likely causes as it has much to 1) Namba, T. 1980. Coloured illustrations of wakan- do with sugar metabolism (1). More studies yaku Vol. 2. Hoikusha Publ. Co., Ltd., Osaka, pp. to identify the allelopathic agent (s) of Japan- 178-180. (in Japanese). ese angelica-tree are necessary. 2) Rice, E.L. 1984. Allelopathy. Academic Press Inc., New York, pp. 266-291. Inhibition of nitrification, of hormone-in- 3) Rice, E.L. 1984. Allelopathy. Academic Press Inc., duced growth, of mineral uptake, interrup- New York, pp. 320-344. tion of mitosis etc. are reportedly action