INVESTIGATION ON THE EFFECT OF SOME PLANT GROWTH REGULATORS ON SUNFLOWER ( HELIANTHUS ANNUUS L.)

With a view to establish the effect of some plant growth regulators on sunfl ower (Helianthus annuus L.) production and oil content was made an experiment. The investigation was made on Bulgarian sunfl ower hybrid Super Start, treated during pinhead and fl owering stages. The effect of the tested plant growth regulators on the quantity of yield and some structural elements (sunfl ower heads number, seeds number, seeds mass, mass/ 1000 seeds, oil content % and oil yield kg/da) was reported in the process of investigation. The effect grade of growth regulators is fi xed due to non-treated control. By the dispersal analysis method it is made mathematics processing of the values of received data. The investigation showed that there is not mathematically proved difference between the seed yield kg/da and oil content l/da in pinhead period by the use of plant growth regulators - ‘‘31’’ (1cm3/l water) and ‘’Agat 25 EK’’ (2.5 g/ da). In the fl owering period when treated with the same plant growth regulators seed yield is 15.3 % increased and the oil content -18.6 % (with “31’’) and 16.4 % (with’’Agat 25 EK’’)