Growth of the onion in summer crop. II
Fresh weight and dry matter content of the leaves for indications of the growth and maturity
1967 Volume 36 Issue 3 Pages 299-305
Details
1967 Volume 36 Issue 3 Pages 299-305
In order to clarify the pattern of growth and maturing process in the onion plant, the fresh weight, dry weight, and dry matter contents of leaf blade and leaf sheath were measured in each of individual leaves through the maturing process in 1960, 64 and 65.
In the ordinary vegetative growth period the growth curve of each leaf was sigmoidal, during which the leaf blade had two stages characterized by low dry matter content. In the first stage the leaf was actively developing and the dry weight of leaf blade reached nearly a maximum, when the leaf would be rich in moisture and nitrogenous nutrients and little in carbohydrates yet. In the second stage, the leaf would be in senescent stage, and the carbohydrates and the other nutrients in the leaf blade would be translocated to more inner leaves through the leaf sheath.
After the beginning of bulb formation, the dry matter contents became low in the leaf blades and the upper part of leaf sheathes in all foliage leaves, and became high in the basal part of leaf sheathes. This would be concerned with the translocation of carbohydrates and other nutrients for the bulb formation. The high content of dry matter in the bulb was maintained untill the bulb attained to full maturity.
In the the transplant culture, after the transplanting, the seedlings increased in dry matter content and swelled in the basal part of the plant. But the dry matter content was low in the living part of the outermost foliage leaf in senescent condition. Thereafter the dry matter content became low in all parts of the plant. This seems to reflect the rejuvanation of the plant resulting from recovering of root systems accompanied by excellent uptake of nutrients and moisture. This physiologically young condition of the plant retarded the initiation of the bulb formation. And this process would compensate for insufficiency of vegetative growth due to a checked effect of the transplanting.
