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Relation between the diameter of the growing shoot and the mature size of leaves and flower head of sunflower
Author(s) -
Pieters George A.
Publication year - 1986
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.1399-3054.1986.tb06604.x
Subject(s) - shoot , sunflower , helianthus annuus , anthesis , biology , botany , horticulture , bud , main stem , cultivar
Helianthus annuus L. cv. INRA 6501 plants were cultivated at irradiances of 15, 30 and 60 W m −2 (400–700 nm) at 20°C and a relative humidity of 60% on a gravel culture subirrigated with Hoagland's nutrient solution. From 10 days after the opening of the cotyledons the diameter of the growing shoot increased linearly with time at a rate dependent on the irradiance. These measurements were continued until the flower bud became visible. By extrapolation of this linear growth to the day of anthesis the diameter of the stem below the flower head was predicted. This stem diameter had a constant ratio (9.7) to the measured diameter of the flower head. In the early stages of development of the plant it is proposed that the diameter of the growing shoot, supported by its vascular system, is a determinant of the size of the mature leaves. Later in the development the diameter of the growing shoot is a determinant of the diameter of the flower head. This change of function is caused by localised activity of the cambial cells which results in tangential growth in the vascular cylinder and ultimately in a hollow stem.