Abstract
The present work is the result of research to measure the influence of food reserves, plant nutrients and temperature on the regrowth of Bahiagrass and orchardgrass in the dark. The term "food reserves" used throughout this paper will refer to the dry weight of the stubble and roots of the grasses. In Bahiagrass, light and plant nutrients had little effect on top regrowth for several days after defoliation. Light and plant nutrients influenced top regrowth after 4 and 8 days, respectively. The effect of light on top regrowth was greater than that of plant nutrients. The effect of light on the dry weight of stubble and roots was observed from the start of regrowth. The decrease of food reserves was markedly higher under dark conditions than under light conditions. This showed that the effects of photosynthesis took place earlier on the stubble and roots of Bahiagrass than on the tops. The regrowth of Bahiagrass was better with large than small seedlings in the 15℃ and 25℃ chambers in the phytotron. In Bahiagrass under the 15℃ and 25℃ chambers, the effect of temperature on the speed of regrowth was more pronounced than the effect of food reserves for the early stage of regrowth. The speed of regrowth was higher under the 25℃ chamber than under the 15℃ chamber regardless of the amount of food reserves. However, the dry weight of new tops was higher in the plants with higher food reserves than in the plants with lower food reserves. The same tendency was observed in the rate of regrowth in Bahiagrass. In the plants of orchardgrass with higher food reserves, the dry weight of new tops at the early stage of regrowth was higher under the 25℃ chamber than under the 15℃ chamber. In the case of plants with lower food reserves, the speed and dry weight of top regrowth were higher under the 15℃ chamber than under the 25℃ chamber. The same tendency was observed in the rate of regrowth in orchardgrass. In both grasses, the decreased weight of food reserves was more pronounced in the plants with higher food reserves and under the higher temperature conditions than in the plants with lower food reserves and under the lower temperature conditions.
