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14 C‐Studies on Apple Trees. VII. The Early Seasonal Growth in Leaves, Flowers and Shoots as Dependent upon Current Photosynthates and Existing Reserves
Author(s) -
HANSEN POUL
Publication year - 1971
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.1399-3054.1971.tb01475.x
Subject(s) - shoot , photosynthesis , biology , botany , petal , annual growth % , horticulture
The young leaves' consumption proper of photosynthates and their contribution to the growth of flowers, fruits and shoots by exposing spurs and shoots to 14 CO 2 at the earliest stages of the growth period in apple trees ( Malus X domestica ) were studied. By a parallel determination of the growth intensity in various organs an attempt is made to evaluate their relative dependence on current photosynthates and on reserves from inside the tree. The proper fixation of 14 C by growth in the exposed leaves is high in the earliest phases of growth. The fixation of 14 C is considerable in the flowers, including the petals, immediately prior to flowering, in intensely growing fruits, and in the woody parts of the current year's shoots, when the main part of the terminal growth has been completed. Under conditions of high intensity of growth in an organ, the total fixation by growth in the parts studied may amount to as much as 80–90% of the 14 C absorbed. Only in the very earliest phases of development does the growth of flowers and shoots appear to be based to a greater extent on materials supplied from reserves than from current photosynthesis. Quantitatively the greater part by far of the total new growth in fruits and shoots appears to be based on materials from current photosynthesis.