[Inhibitory effects of natural plant extracts on Verticillium albo-atrum].

This paper studied the inhibitory effects of 54 kinds of ethanol-extracted plant solutions on Verticillium albo-atrum. The results showed that 15 kinds of these extracts could inhibit the growth of verticillium albo-atrum mycelium, with an inhibitory rate more than 50%, among which, the inhibitory rate of Asarum sieboldii, Coptis chinensis, Magnolia officinalis, Acacia catechu, Sophora flavescens, Glycyrrhiza uralensis, Cnidium monnieri, Platycodon grandiflorum and Allium. cepa. extracts was higher than 65%, and that of Cnidium monnieri extract reached 86.84%. A total of 16 kinds of plant extracts decreased the spore germination of V. albo-atrum, with the inhibitory rate higher than 70%, and there were 7 kinds of plant extracts whose inhibitory rate reached 95%. Almost no spore bourgeon was found after treated with Asarum sieboldii, Coptis chinensis, and Magnolia officinalis extracts. The extract of Acacia catechu did not inhibit the growth of mycelium, but restrained the spore germination by 100%. Cnidium monnieri extract could strongly inhibit the growth of mycelium, but had a less effect on spore germination rate (only by 11.3%). The active substances found in natural plant extracts which had the inhibitory effects on pathogen brought us a new and promising method to deal with V. albo-atrum and other vegetable diseases.

[Allelopathic effects of grafted eggplant root exudates].

By the methods of bioassay, this paper studied the allelopathic effects of different concentrations root exudates from the eggplants grafted with different stocks and at different growth stages. The results showed that compared with that of own-rooted eggplant, the root exudates from grafted eggplants promoted the seed germination and seedling growth of eggplants, and, in comparing with the control (water), they increased the germination rate and plant height by 29.1% and 37.1%, respectively. The seed germination and root length of eggplants was increased at lower concentrations root exudates, but decreased at higher concentrations. The germination rate was increased up to 50% above control at 0.04 g x ml(-1), and the inhibition of root length was up to 30.3% at 0.24 g x ml(-1). The promotion effect of the root exudates from late growth stage grafted eggplants on seed germination was less than that from other growth stage grafted eggplants. Own-rooted eggplant had an intensified inhibitory effect at its late growth stage. Grafting was one of the effective methods for relieving the continuous cropping obstacles caused by autotoxicity.