Growth Responses to Air-and Soil-Temperatures of Orchardgrass and Perennial Ryegrass

[摘要] Eight plots of different temperature combinations of air and soil were established to compare the responses in growth and chemical constituent both in orchardgrass and perennial ryegrass plants, grown in 4 phytotrons with different air-temperatures from 90 to 28°all dry under natural day light. 1. In both grasses, the growth in terms of plant height, leaf-emergence rate, heading date, tiller number, leaf area and dry matter production was promoted by raising or lowering several degrees of soil-temperature when the air-temperature was lower or higher than the optimum, respectively. The production of dry matter was highest in air 17°-soil 23°plot, followed by 23-17°, 23-23°and 17-17°. 2. Generally, nitrogen concentration of each organ was higher under cooler air-temperatures, although a little higher under 28°. With the growth promotion by the soil-temperature alteration, both nitrogen concentration and Sol-N/Tot-N ratio declined. TAC concentration increased with the increase of air-temperature in orchardgrass, whereas decreased in perennial ryegrass. The concentration was generally higher under the soil-temperatures whereby the growth was promoted. Therefore, Tot-N/TAC ratio was greater under cooler air-temperatures in orchardgrass but smaller in perennial ryegrass, and in both grasses declined with the greater growth rate induced by the alteration of soil-temperature. 4. Both crude protein and TAC production were less under 9°and 28°, higher under 17°and 23°air-temperatures, respectively, being highest under 17-23°and 23-17°conditions. In the regime of this experiment, it is suggested that the production of protein and TAC increase in parallel with that of dry matter.

[学科分类] 农业科学（综合）