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    Determination of the effects of growth regulators on pollen viability and germination level of tulip
    (Int Soc Horticultural Science, 2019) Akcal, A.; Gokbayrak, Z.; Engin, H.
    The present study was focused on determining the effects of brassinosteroid, naphthalene acetic acid and gibberellic acid on in vitro pollen germination and pollen viability of tulip. Knowledge on different sources of pollen is an important issue for ornamental plant growers or breeders especially in crossing procedures for tulip. Flower bud formation and inflorescence is affected by bulb size, environment, irrigation, nutrition and many other factors. In some ornamental plants pollen quality as well as cultivar affect viability and germination characteristics. Tulipa greigii `Pinocchio' was used as a pollen source which was tested for its ability to germinate in vitro on a medium (1% agar and 20% sucrose) containing three different group of hormones, gibberellic acid (GA3), naphthalene acetic acid (NAA) and epibrassinolide (EBR). After 24 h of incubation, pollen were evaluated and germination ratios were determined. The results indicate that pollen germination was significantly affected by growth regulators while pollen viability and germination rates were altered according to the concentrations and the type of the growth regulators. The highest average value of the pollen germination rate (42.95%) was determined in the concentration of 0.1 mg L-1 EBR treatment in Tulipa greigii `Pinocchio', while the highest value (92.47%) for the pollen viability was obtained from epibrassinolide (EBR) in comparison to the other hormones.
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    Gibberellic Acid Inhibits Floral Formation and Delays Flower Differentiation in '0900 Ziraat' Sweet Cherry Cultivar
    (Int Soc Horticultural Science-Ishs, 2014) Engin, H.; Gokbayrak, Z.; Akcal, A.; Gur, E.
    This paper reports on the effects of gibberellic acid (GA(3)) on floral formation and the potential for GA(3) to reduce flower primordia formation in sweet cherry (Prunus avium L.). GA(3) was applied to 4-year-old '0900 Ziraat'/'Gisela 5' trees at two growth stages (early flowering and beginning of fruit development) at the doses of 0, 25, 50, 100, and 250 mg L-1, for a 2-year period. Bud samples were taken from the beginning of July to the end of September in both years in six sequential dates. During the dormant seasons, buds were collected to determine number of flowers per bud. Samples were fixed and stored in a solution of formalin, 70% ethanol and glacial acetic acid (10:50:5, v/v). Flower formation in the buds was examined using a stereo zoom microscope and the morphological changes in each sample were recorded using a camera mounted on the microscope. Number of flowers per bud was negatively and linearly related to GA(3) concentration. Floral formation in '0900 Ziraat' sweet cherry (untreated control) started in early-July and continued until mid-September. The progress during which the sepal, petal, stamen and pistil primordia were differentiated was considerably slower at GA(3) applications. Imperfection of the floral buds was observed as the floral organs being replaced by leaf-like appendages or as none of the flower buds having one normally-developed flower primordia or as floral organs or flower primordia being much smaller than the other.
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    Öğe
    Influence of shoot topping on yield and quality of Vitis vinifera L.
    (Academic Journals, 2008) Dardeniz, A.; Yildirim, I.; Gokbayrak, Z.; Akcal, A.
    This study was carried out in a 20 year old spur pruned Karasakiz (Kuntra) vineyard during the 2003 and 2004 growth season. Vines were topped at 1, 3 and 5 nodes beyond the last cluster on the main shoot. Yield and quality parameters were analyzed to determine the effects of shoot topping. The results showed that weather conditions had more statistically important effects compared to the topping level. One (1) node topping resulted in more loss of yield due to increased vegetative growth.