1977 Volume 45 Issue 4 Pages 342-348
1. The relationship between gall swelling and plant growth regulators after inoculation of an egg mass of root-knot nematode (Meloidogyne incognita var. acrita) on the second internode of the balsam plant (Impatiens balsamina) were studied. Changes in levels of auxin, cytokinin, gibberellin and ethylene, and the effect of application of exogenous plant growth regulators (GA3, GA4+7, IAA, KN, MH, CCC, B-9) on gall swelling were investigated.
2. Auxin and cytokinin activity sharply increased one week after inoculation, and no further increase was found thereafter. Ethylene evolution from the gall tissues significantly increased during gall swelling. Endogenous levels of auxin, cytokinin and ethylene in the gall tissues were considerably higher than those in the normal tissues at every stage.
3. GA3, IAA and especially IAA+KN promoted gall swelling, while plant growth retardants such as CCC, B-9 and MH remarkably inhibited gall swelling when applied one week after inoculation. When plant growth retardants applied 3 weeks after inoculation, KN and IAA+KN promoted gall swelling, and IAA+KN was as effective as its application at one week after inoculation, while CCC and B-9 inhibited gall swelling. Ethrel concentration was proportional to gall swelling in the range between 100 and 500ppm.
