Maintenance of high epidermal cell density and reduced calyx-end cracking in developing 鈥楶ink Lady鈥?apples treated with a combination of cytokinin 6-benzyladenine and gibberellins A₄+A₇

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• 作者：Idit Ginzberg ; Edna Fogelman ; Lior Rosenthal ; Raphael A. Stern
• 关键词：Fruit cracking ; Malus  ; &times ;   ; domestica ; Peel anatomy ; Plant growth regulators
• 刊名：Scientia Horticulturae
• 出版年：22 January, 2014
• 年：2014
• 卷：165
• 期：Complete
• 页码：324-330
• 全文大小：861 K

文摘

Calyx-end cracking in 鈥楶ink Lady鈥?apple develops as concentric cracks located around the stylar-end. The factors that induce the cracking are unknown, however we previously demonstrated that the intensity of the disorder can be controlled by application of a mixture of synthetic gibberellins (GA₄ plus GA₇) and cytokinin (6-benzyladenine; BA) at different phenological stages of fruit development, and suggested that the plant growth regulators (PGRs) affect the elasticity of the epidermal layer at the calyx-end by increasing cell density. The present study focused on histological analyses of the peel at the calyx-end following the application of BA + GA₄₊₇. The experiments were conducted in Northern Israel during 2011 and 2012. In 2011 the PGRs were applied as 0.2% (v/v) Superlon鈩?(i.e., 40 mg l^鈭? BA plus 40 mg l^鈭? GA₄₊₇) once, twice or three times every 14 days since 60 days after full bloom (DAFB). In 2012, to test the efficacy of a lower concentration of the PGRs, 0.025% (v/v) Superlon鈩?was used. Spraying was applied at 60 to 90 DAFB (cell expansion phase) as before, in addition to earlier spraying at 7 to 35 DAFB (cell division phase). In all treatments given at cell expansion phase the BA + GA₄₊₇ mixture increased the epidermal cell density at the calyx-end, compared to control. Multiple spraying maintained the high cell density during fruit expansion compared to one-time application, and the higher concentration of the PGRs was more potent than the lower. Assessment of calyx-end cracking suggested that low concentration of the PGRs (i.e., 5 mg l^鈭? BA plus 5 mg l^鈭? GA₄₊₇) is most efficient when applied three times at cell division phase.

Interestingly, in 2011 the incidence of calyx-end cracking was significantly lower relative to 2012 and 2010 that were characterized by extended daily hours of high temperatures (>34 掳C). This association can be used by growers as a criterion in applying the PGR treatment early in the season when temperatures are higher than the average and high incidence of calyx-end cracking might be expected.