Articles
EFFECTS OF LOW SEEDBED TEMPERATURES ON SEEDLING WEIGHT
The data suggested that the weight of the seedlings at emergence was less in early-sown crops than in late-sown ones.
Experiments were done in controlled environments to investigate this effect.
Temperatures of 12.5° and 20° were used.
The mean weight of seedlings of P. vulgaris at emergence was 73.6% of the initial seed weight.
The value was hardly affected by temperature regime.
Similar values were found for all varieties tested.
The weight of the seedling axis at emergence varied more than twofold with temperature.
For plants held at 20° the mean axis weight at emergence was 26.3% of the initial seed weight; for plants raised at 12.5° it was 12.4%.
Reductions in axis weight at emergence due to low temperatures during germination were also observed in P. coccineus, Glycine max, Zea mais, Cucurbita pepo, Vicia faba and Pisum sativum.
The effects were most marked in certain cultivars of P. vulgaris, and least marked in Vicia faba and Pisum sativum.
The phenomenon occurs because the mobilisation of seedling reserves is more affected by temperature than is the elongation of the seedling axis.