EFFECT OF SOME GROWTH RETARDANTS ON GROWTH AND FLOWERING OF HELIANTHUS ANNUUS L. CV. SUNRICH ORANGE SUMMER 981V PLANTS A- EFFECT OF FOLIAR SPRAY TREATMENTS WITH ANCYMIDOL, DAMINOZIDE AND ETHEPHON

Pot experiments were carried out at the nursery of Hort. Res. Inst, Giza, Egypt throughout the two successive seasons of 2014 and 2015. The work embodied in this paper was to study the influence of some growth regulators (daminozide, ancymidol and ethephon) on sunflower (Helianthus annuus L. cv. Sunrich Orange Summer 981V) plant for achieving the hope of producing dwarf plant of good quality, suitable for using as a pot plant.
Results indicated that most treatments reduced stem length of the treated plants with the superiority of 2450 ppm daminozide treatment which induced 50% reduction in such trait, compared to the control plants in the two seasons. However, stem diameter and number of internodes/stem were improved in response to all the used treatments. Internode length, stem fresh and dry weights were decreased with few exceptions, but the greatest decrease in these criteria was attained by daminozide treatment at any rate and ethephon one at 250 ppm. Number of leaves/plant were increased by the various treatments. Root length increased over control with few exceptions in both seasons. However, the highest averages in most measurements were achieved by ancymidol, especially at 20 ppm level. A significant flowering earliness in the two seasons was noticed in plants sprayed with ethephon at 250 ppm. The least number of days from flower bud appearance to opening was obtained by the 20 ppm ancymidol treatment, but the plants treated with the other treatments took longer time to anthesis. Ethephon treatments elevated the mean number of lateral buds/stem to the maximum, while ancymidol ones gave the largest flower heads. Number of ray flowers/head, disc diameter and flower head fresh and dry weights were improved due to most treatments. Content of photosynthetic pigments were slightly improved with few exceptions. Total phenols content reached the maximum by ancymidol treatments, followed by the ethephon ones. However, total indoles content was not affected by most of the used treatments. In addition, the percent of total soluble sugars was increased by ancymidol at 5 ppm, daminozide at 2450 ppm and ethephon at 500 ppm treatments, while other treatments declined it. On the other hand, the percent of N, P and K was generally decreased in response to the various treatments, with few exceptions as compared to control.