EFFECT OF SOME PLANT GROWTH REGULATORS WITH RETARDING ACTIVITY ON SPRING PEA FOR GRAIN

A field experiment was conducted at Trakia University - Stara Zagora to establish the effect of some growth retardants on morphological and productive parameters in spring pea for grain variety Bogatir. Three combined preparations: Trisalvit (phenylphthalamic acid + chlorocholine chloride + chlorophenoxyacetic acid +salicylic acid) at doses of 300 and 400 сmз*ha-1; SM-21 (phenylphthalamic acid + chlorocholine chloride) at doses of 300 and 400 сmз*ha-1 and PNSA-44 (phenylphthalamic acid + naphthaleneacetic acid + chlorophenoxyacetic acid) at doses of 200 and 300 сmз*ha-1 were applied in the early growth phase of the plant up to a height of 15-20 cm. The study showed that the greatest reduction in the stem height (by 12.8% compared to untreated plants) was achieved by applying SM-21 (400 сmз*ha-1). The application of growth regulators Trisalvit and SM-21 had no appreciable effect on the production of spring pea grain. Maximum values of yield structure components (number of pods and grain per plant, grain mass per plant and mass of 1000 grain) and the yield were obtained after application of PNSA-44 (300 сmз*ha-1) - up to 5.6% (117.2 kg*ha-1) more grain than the control. The investigation of the influence of tested factors (retardant, dose and year) demonstrated that the conditions of the year as a factor had the strongest effect on plant height and grain yield.