Volodymyr P. Allelopathic action of cereals exome-tabolites in phytocenoses

4. The object is allelopathic properties of crop species; allelopathic activity of root excretion of grain phytocenosis edificators; the connection of wheat productivity on allelopathically active substances. The methods of researches are the following: field methods; laboratory methods (biochemical, chemi-cal, microbiological and cytological analysis); sta-tistical methods. It is determined, that allelopathic activity of root excretion of grain phytocenosis edificators is stipulated by nucleic acids, group B and inosite vitamines, and other compounds. Excretion of allelopathically active substances by the room system depends on the species, sort, stage of ontogenesis and environmental conditions. Allelopathic activity and tolerance of cultivated grains depend on their species and sort. Root excretions of rye posess the highest activity. Then grain species are arranged as to their allelopathic activity in the following order: triticale > hard wheat > soft wheat. Allelopathic tolerance of soft wheat isbetter than the hard one. The use of a separate plant of one species in agrophytocenosis of the other one as a parent form increases crossing of different species of wheat, wheat and rye, viability of the first generation of hybrids and changes phenotype variability in the population of the second generation of hybrids. Such approach as well as the elaborated idea about the allelopathic mechanism of agrophytocenosis allowed to explain the reasons of arriving spontaneous hybrids of different grain species. On the basis of studying allelopathic properties of grain crops, it was scientifically grounded the use of mixed sowing of different grain species to increase crossing under distant hybridization. The possibility of using exometabolites of a germinating seed (extraction) for increasing winter and spring wheat productivity is proved. The increase of the winter wheat yield is 3,6-6,2 c/ha, while the spring wheat yield is 3,5-3,7 c/ha.