makes this cultivar a good model for studying these mechanisms. Plant growth regulators have been implicated to play a major role in controlling flower initiation and biennial bearing in apple. Exogenous application of gibberellins (GAs) soon after full
Mokhles A. Elsysy and Peter M. Hirst
Fatih Ali Canli, Murat Sahin, Nurettin Temurtas, and Mustafa Pektas
at harvest time is largely affected by cell division and cell enlargement at the initial periods of fruit development ( Bohner and Bangerth, 1988 ; Zhang et al., 2005 ). Plant growth regulators [PGRs (auxins, gibberellins, and cytokinins)] are used
Jaser A. Aljaser and Neil O. Anderson
, such as gibberellins, particularly GA 3 and GA 4+7 ( Thomas and Hedden, 2006 ), has also been shown to increase cormel production. Gibberellins can increase the number of gladiolus cormels by means of exogenous applications ( Khan et al., 2011
Melvin R. Hall
Immersion of sweetpotato [Ipomoea batatas (L.)] storage roots in low concentration (5 and 50 mg·liter-1) of gibberellic acid (GA) in solutions of benzyl adenine plus GA4+7 increased early but not total plant production from bedded roots of `Georgia Jet' and `Jewel'. Immersion in 0.5 and 1 mg·liter-1 solutions of GA3 increased early plant production from `Georgia Jet'. Neither weight nor visual appearance of the harvested plants nor root yield from transplants were influenced by gibberellin treatments of the bedded roots.
Irfan Ali Sabir, Xunju Liu, Songtao Jiu, Matthew Whiting, and Caixi Zhang
studies on the effects of PGRs in tree fruit, and results vary with PGR application timing, concentration, and even with application technology. In previous studies, preharvest applications of gibberellins during the stage II–III transition in sweet cherry
Caixi Zhang, Kenji Tanabe, Hiroko Tani, Hiromitsu Nakajima, Minori Mori, and Emi Sakuno
Gibberellins form a group of more than 130 tetracyclic diterpenes, some of which are biologically active, such as gibberellic acid 1 (GA 1 ), GA 3 , GA 4 , and GA 7 , and act as endogenous regulators of plant growth and development ( Davies, 2004
Jun Ban and Frank G. Dennis Jr.
Some apple cultivars are biennial. Experiments with the facultatively parthenocarpic apple cultivar `Spencer Seedless' indicated that seeds are responsible for inhibiting flowering (Chan and Cain, Proc. ASHS 91:63-68, 1967). Because gibberellin inhibits flowering in apple, seed GAs may be responsible for biennial bearing, or seeds may affect metabolism of GAs in bourse shoots. To obtain additional information, 14C - G A12 was injected into seeds or bourse shoots of `Spencer Seedless' and the metabolites were extracted after 24 or 48 hr. Metabolites moved from seeds to bourse shoots and vice versa in 1992, only the most polar compound(s) being transported. However, transport was not observed in 1993. Five metabolites of 14C - G A12 were found in apices following injection, 5 to 7 in seeds. Two metabolites occurred in fruit flesh following seed treatment. The presence of seeds appeared to have no qualitative effect on metabolism in the bourse shoot, although the metabolites have not yet been identified.
Graham H. Barry and Smit le Roux
roots, beside other organs, are a major site for the biosynthesis of gibberellins and cytokinins, which are antagonistic to rind color development and are subsequently transported to the aerial portion of the tree through the xylem ( Saidha et al., 1983
Moritz Knoche, Bishnu P. Khanal, and Matej Stopar
., 1997 ). Under orchard conditions, russeting is avoided and peel appearance improved in sensitive cultivars by applying gibberellins such as gibberellic acid (GA 3 ) or GA 4+7 ( Elfving and Allen, 1987 ; Meador and Taylor, 1987 ; Steenkamp and
Lívia Lopes Coelho, Amalia Fkiara, Kathryn Kuligowska Mackenzie, Renate Müller, and Henrik Lütken
many plants, the flowering response is closely linked to endogenous hormonal levels, which is directly or indirectly associated with their developmental stage ( Bratzel and Turck, 2015 ). Gibberellins are a class of hormones that play multiple roles in