The Effect of Chilling Temperature on the Growth Responses of Tropical and Subtropical Grass Species

Abstract

To determine the growth responses to chilling temperature at early stage of development for three species of dallisgrass, setaria and green panic, growth analysis was carried out under the constant air temperature treatment of 15, 20 and 30℃ in the natural light condition at the Biotron Institute, Kyushu University. At the temperatures of 15 and 20℃, differences were found among the species in the values of relative growth rate (RGR) and other attributes. The growth depression or low value of RGR under the chilling temperature was closely correlated with the decrease in relative leaf (area) growth rate (RLGR) for three grass species and also in net assimilation rate (NAR) especially for green panic. Comparison of temperature coefficient Q_10 of RGR, RLGR and NAR indicated that dallisgrass was very responsive to chilling temperature only in RLGR, but for green panic there was high in all three attributes, while setaria had intermediate response between other two grasses. It was suggested that the specific growth response to chilling temperature was closely related to the winter hardiness and hardening process of each grass.