Environmental influences on juvenile shoot growth in Picea abies
1991
Wuehlisch, G. von | Muhs, H.J. (Federal Research Centre of Forestry and Forest Products, Grosshansdorf (Germany). Inst. of Forest Genetics and Forest Tree Breeding)
Under certain environmental conditions juvenile shoot growth characters might give early indications of adaptability and growth potential. Therefore, the reaction patterns of predetermined and free shoot growth were studied on Picea abies (L.) Karst. plants, which at different times during the growth period were treated by (1) application of nutrients, (2) defoliation and (3) short days. Fertilization caused an increase in both predetermined and free growth, while defoliation and short day treatment caused a decrease in both forms of shoot growth and short days did not allow any free growth to occur. In the growth period following the treatments, fertilization caused more predetermined and less free growth to occur, while defoliation caused less predetermined and more free growth. Predetermined growth is explainable by the finite number of predetermined needle primordia. Free growth is initiated thereafter. It is influenced strongly by the environmental conditions and seems not to be influenced by the amount of preceeding predetermined growth. Free growth enables young plants to utilize favourable growth conditions in summer height growth precociously, which might increase their adaptability and competitive value. However, predetermined growth is the preferable mode of shoot growth because favourable conditions in successive growth periods induce more predetermined than free growth. Predetermined and free growth are well integrated forms of shoot growth giving no supporting evidence to the hypothesis that free and predetermined growth are inherited independently of each other. Rank changes in provenance development are probably not explainable by a loss in height growth when free growth occurs no more due to age, but by other causes.
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