GROWTH HABITS OF THE VEGETATIVE APPLE ROOTSTOCK MM 106 AFTER TREATMENT WITH SOME SOIL HERBICIDES UNDER IN VITRO CONDITIONS

Abstract

The strong susceptibility of the fruit species used as rootstocks to herbicide application necessitated the studies on the vegetative habits and physiological status of the plants with the aim of optimizing the weed control in the production of certified fruit planting material. The aim of the present study was to develop an in vitro test system for preliminary screening of the effect of some soil herbicides on the growth habits of vegetative apple rootstocks. Micropropagated and rooted plants of apple rootstock ММ 106 (root length about 10 mm) were treated with the soil herbicides pendimethalin and napropamid. The following variants were set for the experiment: 1. Control (untreated); 2. Pendimethalin – Stomp 33 EC – 4.0 L/ha; 3. Pendimethalin – Stomp 33 EC – 6.0 L/ha; 4. Napropamid – Devrinol 4F – 4.0 L/ha; 5. Napropamid – Devrinol 4F – 4.0 L/ha. The rates of the respective herbicides were recalculated according to the area of the cultural vessel. In both variants with napropamid applied appearance of necrosis in the root tips was observed on the 7 th day. On the 14 th and 21 st days those symptoms were much more expressed and stem growth suppression was also reported. It was established that pendimethalin and napropamid depressed the stem and root growth of the treated plants. The inhibiting effect of napropamid on those characteristics was expressed even more strongly. Both soil herbicides did not exert any significant effect on the mean number of roots per plant. The application of those herbicides was the reason for the lower content of leaf pigments (chlorophyll а, β, а+β and carotenoids), the strongest depressing effect being reported after treatment with napropamid.