DIFFERENT GROWTH OF 2 BIOTYPES OF COMMON GROUNDSEL (SENECIO-VULGARIS L) GROWN IN NATURAL CLIMATIC CONDITIONS

When growing the susceptible and the resistant common groundsel (Senec io vulgaris L.) in natural climatic conditions, a marked reduction of fresh matter of above-ground parts (with the exception of the third we ek) and of dry matter of above-ground parts, as well as of fresh and d ry matter of rods (with the exception of the third week) was observed in the resistant biotype in the intervals of three to seven weeks afte r sowing. The number of leaves was lower in the resistant biotype with out considerable differences also the length of rods was reduced in an insignificant way (except for the seventh week after sowing). The pho tochemical activity of chloroplasts was reduced in the resistant bioty pe in all the intervals after sowing in comparison with the susceptibl e biotype. The results confirm a transformation chloroplasts of the re sistant plants which affects their physiological function and induces a lower productivity of the whole plant also under natural climatic co nditions