La première feuille des plantules d'orge. II. Croissance en longueur

The growth in length, of the first leaf was studied after an improvement by line breeding and seed grading. Similar to leaf initiation which occurs in two distinct periods for the blade and for the sheath, the growth curve of the whole leaf equals the sum of the growth curves for the blade and for the sheath, respectively. The relative growth rate for the whole leaf reaches a maximum, then decreases with a shoulder. The maximum corresponds to the greatest relative growth rate for the blade. The change in the rate of decrease corresponds to the beginning of the sheath growth at the moment when the blade is emerging.