اثر پاكلوبوترازول و طول روز بر رشد رويشي و زايشي دو رقم توت فرنگي

چكيده انگليسي :

Effect of Paclobutrazol and Short Day Condition on Vegetative and Reproductive Growth of Two Cultivars of Strawberry Fatemeh Shakeri f shakeri@ag iut ac ir February 15 2009 Department of Horticultural Sciences Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language farsiBahram Baninasab bbanin@cc iut ac irCyrus Ghobadi cyrus@cc iut ac irAbstractExcessive growth of some strawberry cultivars grown under control conditions for a one year cycle or inhigh density planting systems may often cause irregular pollination reduced fruit set a greater incidenceof misshapen fruits and fungal disease and a delay in ripening To avoid these problems partialdefoliation before flower emergence or during bloom is a common practice A different approach tocontrol vegetative growth operations currently done by hand or mechanical means is represented by theuse of growth retardants which to be suitable should reduce the vegetative growth without adverselyaffecting yield fruit quality and reduce hand labor Out of season production is another problem incultivation of strawberry In June bearing strawberries short days is necessary for flower initiation andflowering to produce one crop per growing season On the other hand growth regulators with similareffects of short days on flower initiation may promote out of season production and increase yield instrawberries Paclobutrazol is one of the most applicable triazole compounds and is widely used ininhibiting extension growth and promoting plant flowering in different methods Therefore this researchwas conducted in two separate experiments In the first experiment the effects of applying different rate ofPaclobutrazol on vegetative and reproductive growth of strawberry cv Selva were studied with differentapplication methods drench and foliar spray A factorial experiment in a completely randomized designwith three replications was used Paclobutrazol was applied at 0 0 5 1 1 5 and 2 mg active ingredient perplant at 3 to 4 leaves stage Results of first experiment indicated that appling of Paclobutrazol reducedleaf area petiole length shoot fresh and dray weight while petiole diameter leaf chlorophyll content andharvest index increased Using paclobutrazol at rate of 1 mg active ingredient per plant lead to maximumincrease in yield 17 27 High rate of Paclobutrazol reduced root growth and diameter Applications ofPBZ as foliar spray was more effective than soil drench in reducing leaf area shoot fresh weight andincreasing harvest index Also foliar spray of PBZ decreased shoot dry weight more than wet weightwhich makes this method more effective in increasing assimilate and dry material compared to soildrench Interaction of Paclobutrazol and its method of application on characteristics including leaf area petiole diameter were significant The second experiment studies the possibility of applying Paclobutrazolin long day conditions as a substitute for short day conditions which leads to flower induction and out of season production June bearing strawberry cv Comerosa In this experiment the effects of short days SD various rates of paclobutrazol 0 2 0 4 and 0 6 mg active ingredient per plant PBZ at non inductive day lengths and their combinations were investigated The experiment was a completelyrandomized design with fore replications Results of second experiment indicated that applying of PBZ inlong days increased leaf chlorophyll contents plant dry weight number of leaves diameter of petiole androot dry weight compared to SD treatment Also decreasing content of applied PBZ in the secondexperiment had positive effect on root growth and consequently root increment Application of PBZ at therate of 0 6 mg per plant led to 216 67 and 206 increase in flower numbers and yield respectively whencompared to SD treatment But this treatment reduced leaf area and petiole length Also SD PBZtreatments had no significant effect on number of flower per plant when compared to SD treatment Therefore in this stud

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اثر پاكلوبوترازول و طول روز بر رشد رويشي و زايشي دو رقم توت فرنگي

روز كوتاه , توت فرنگي رقم سيلوا , توت فرنگي رقم كامروسا