The paper demonstrates that air exometabolites of plant natural and cut leaves and flowers are proved to effect the bio tests – seed germination. The degree and character of this influence quantity and character differ for various donor and acceptor plants. The biological action of products of plants transpiration remains under its accumulation in the activated carbon and frozen water. It is shown that the interaction of some plants on the others is caused by the interrelation of both aboveground organs and root systems. So,under beetroot seed generation the size of the seedlings roots in the controlled variant was 5.5 ± 0.9 cm, the stem size was 4.6 ± 06 cm. When growing sorrel and beetroot seeds together,the beetroot size of the roots was 3.1 ± 1.0 cm; the stem size was 3.1 ± 1.0 cm. It seems feasible to take into consideration this influence under combined planting of several crops.