Responses of Subterranean Clover Communities to Temperature. II. Effects of Temperature on Dark Respiration Rate

Abstract

The rates of dark respiration of subterranean clover communities, grown at 12, 16, 20 and 24°C in naturally lit temperature-controlled glasshouses, were measured several times during growth. The dark respiration rate, measured at growth temperature, increased linearly with increase in plant dry matter for each temperature and it increased approximately linearly with increase in temperature at a given dry matter. A low crop growth rate shown by communities with dry matter greater than 300 g m^-2 at a temperature of 24°C was largely accounted for by a high respiration rate. The temperature coefficient of dark respiration (Q₁₀) was inversely related to growth temperature. Dark respiration rate at 28°C was lower for communities grown at 24°C than for communities grown at 12 or 16°C when the comparison was made at the same dry matter. Calculated dark respiration rate from shoot dry matter, growth temperature and current measured temperature was close to the measured rate, indicating the dark respiration rate of subterranean clover communities to be largely accounted for by these factors. Use of an integrated form of a growth equation and allowing for dark efflux shows, on a 12 hour day, the rate of dry matter accumulation at 24°C to be the same as that at 12°C.