Premium
Comparison of growth and gibberellin concentrations in shoots from orchard‐grown standard and thermosensitive dwarf apple trees
Author(s) -
Steffens G. L.,
Hedden P.
Publication year - 1992
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1992.tb02168.x
Subject(s) - shoot , orchard , biology , dwarfing , gibberellin , horticulture , dwarfism , botany , malus , fruit tree , rosaceae , rootstock , hybrid , biochemistry , gene
Apple ( Malus domestica Borkh.) trees were propagated by budding from selected fully grown hybrids that ranged in height from 1.5 to 8 m. The growth and development of the selected budded trees after 7 years in the orchard was similar to that of the parent trees. Additional grafting studies showed that the dwarfism was not associated with the roots. Differences in photosynthetic activity and associated processes were not related to the size difference between tissue culture‐propagated orchard‐grown standard cv. Golden Delicious and dwarf hybrid trees. Applications of GA 3 did not stimulate elongation of shoots of dwarf trees. Shoots of both standard and dwarf trees started to develop in mid‐April when they contained nearly the same amounts of GA 1 , GA 3 and GA 8 , but standard shoots contained higher concentrations of GA 19 , GA 20 and GA 29 . On 2 June standard shoots were almost three times the length of dwarf shoots, but the number of leaves and area per leaf were nearly the same. The relative amounts of GAs on 12 May and 2 June for both plant types were similar to those on 20 April, except that GA 19 , GA 20 , GA 1 and GA 29 levels had declined. Gibberellin levels in standard shoots declined further between 2 and 22 June, after which there was no further shoot elongation or production of new leaves. Between 2 June and the end of the growing season, when summer temperatures were high, dwarf shoots continued to elongate slowly and to develop new leaves, which expanded little. During this time, the GA 19 content of dwarf shoots nearly doubled, whereas the amounts of GA 20 , GA 1 , GA 29 and GA 8 declined. By the end of the season, standard shoots were 40 cm in length with 20 leaves and dwarf shoots were 28 cm in length, but with 36 leaves. High summer temperatures appear to induce loss of GA‐responsiveness in orchard‐grown dwarf trees and to cause a reduced rate of conversion of GA 19 to GA 20 in these genotypes.