THE GERMINATION OF LIGHT-SENSITIVE SEEDS OF TYPHA LATIFOLIA L.

Publisher Website
Google Scholar
Abstract
Germination in Typha lalifolia L. is strongly favored by white light and by low oxygen concentration. Microscopic study shows that the effect is on the aleurone grains, whose colloids are so affected that they attract and hold water more strongly, and the resultant swelling ruptures the seed coat. The swelling of the grains was observed under various sets of conditions. Its progress is described and has a bearing on current theories with respect to these structures. The process of vacuolation in the cells was also studied. On it light has no apparent effect, but it is notably stimulated under conditions of vigorous, aerobic respiration. In some samples of seed, where the tendency to vacuolate is especially strong, atmospheric pressure of oxygen strengthens vacuolation to an extent that will compensate for its depressing effect on swelling of the grains, and satisfactory germination follows. In other samples this is not so. Under very low light intensity, rather wide alternations of temperature promote germination. This was found to be due to promotion of vacuolation. Respiration studies show slow respiration and a low respiratory quotient at the low temperature. It is suggested that this allows a clearing away, during the time at low temperature, of the products of respiration, thus allowing, when the higher temperature is resumed, the vigorous respiratory activity that makes for vigorous vacuolation.