EFFECT OF HARVESTING AT DIFFERENT DATES O N THE GERMINATION OF WINTER-WHEAT

The authors carried out studies with winter wheat varieties produced f or seed by methods applied at ripening dynamics studies and it was sta ted how the different harvesting dates - ripening stages - affected th e germinability of seeds. The tests were carried out al four occasions , on 7-10-20-22 July, i.e. at repening dates Tl-T2, T2-T3. The finding s can be summed up as follows: the results are affected not only by ha rvesting dates, but also by the characteristics of the individual vari eties; the thousand-grain-mass parallel increased with the progress in ripening, i.e. it was the highest at the end of phase T1 and at the b eginning of T2, but at the end of phase T2 there was already a decreas e in yield except for variety Mv 21 where the thousand-rain-mass remai ned the same also in stages T2 and T3; that means that the interval of its harvesting time is longer, its harvesting should not be rushed; s eed vigour in all varieties is the best during the first two harvestin g periods - at the end of T1, at the beginning of T2 -, while in the l ater periods the germination power declines by 4-5% depending on varie ty; the germination percentage is the highest also during the first tw o harvesting periods - end of T1, beginning of T2; the germination res ults according to the number of generations do not show reliable devia tion, only the first generation seed of variety Mv 23 showed reliable difference.