Free and conjugated gibberellins in dormancy and germination of apple seeds

Abstract

Halińska, A. and Lewak, St. 1987. Free and conjugated gibberellins in dormancy and germination of apple seeds. The presence of gibberellin A 4 (GA 4 ) was confirmed in partly stratified seeds of apple ( Malus domestica Borb., cv. Antonówka) by mass spectrometry of the methyl ester. Levels of free and conjugated gibberellins A 4+7 and A 9 changed during drying of mature seeds, during cold and warm stratification, as well as during germination of dormant and non‐dormant embryos. The temporary rise in GA 4+7 during cold stratification and during the culture of dormant embryos as well as the lack of it under conditions of warm stratification, allowed us to postulate a role for GA 4+7 in the removal of dormancy. In addition, GA 9 was absent in dormant embryos and increased during cold stratification and during the culture of non‐dormant embryos. This suggests the involvement of GA 9 , in induction of normal development of the seedling. The equivalence between changes in free and conjugated GAs suggests that formation and hydrolysis of conjugates are involved in the control of the physiologically active levels of free GA 4+7 and GA 9 .