CROISSANCE DES PLANTULES DE CAROTTE DE LA GERMINATION JUSQU'A L'APPARITION DES PREMIERES FEUILLES

V. Tamet, C. Durr, J. Boiffin
This study of the growth of carrot seedlings was carried out under controlled conditions, at 20°C and 10°C. The study focused on two different seed weight categories of the NANDOR variety (a Clause F1 hybrid, size 1.60–1.80 mm). Both seeds and plants were subjected to non-limiting conditions of water and mineral supply. In the dark, the growth of the young seedling following germination involves three successive phases:
  1. Transfer of seed reserves to the seedling via the cotyledon: upon completion of this phase, the seedling separates from the seed, which no longer contributes to its growth.
  2. Redistribution of reserves within the seed, essentially from the cotyledons toward the hypocotyl ; the latter then continues to grow alone, in both weight and length.
  3. End of redistribution. The weight of the cotyledons stabilizes at its lowest level; the weight and length of the hypocotyl cease to increase.

This pattern was repeated in all of the experimental varieties tested. The duration of germination and of each phase is greater at 10°C than at 20°C. However, using the thermal time calculated with a base temperature of 3.5°C, the organs studied at 10°C and 20°C evolve according toan identical pattern.

The weight of the seedlings, as well as the weight and final length of the organs, depend on the initial weight of the seeds from which they are grown.

Autotrophic growth of seedlings was studied by exposing them to light subsequent to dark periods of varying duration. The parameters of the growth curves(of the exponential type) depend on seed characteristics and on the duration of the period of heterotrophic growth. The ordinate at the origin of the curve is strongly linked to the initial weight of the seed from which the seedling is grown. Although the growth rate declines when the period of heterotrophic growth is extended, it is the same for both categories of seed weight. It depends on the condition of the cotyledons when they are exposed to light, as the behavior of the cotyledon changes when it is kept in darkness for an extended period.

Tamet, V., Durr, C. and Boiffin, J. (1994). CROISSANCE DES PLANTULES DE CAROTTE DE LA GERMINATION JUSQU'A L'APPARITION DES PREMIERES FEUILLES. Acta Hortic. 354, 17-26
DOI: 10.17660/ActaHortic.1994.354.2
https://doi.org/10.17660/ActaHortic.1994.354.2

Acta Horticulturae