地毯草的光合特性研究

地毯草是一种典型的暖季型草坪草。用Li 6400便携式光合分析仪测定地毯草的光合特性。地毯草的光合日进程呈单峰型,无"午休"现象且受非气孔限制,最大净光合速率出现在14∶00,变化趋势与光合有效辐射(PAR)、气温(Ta)、蒸腾速率(Tr)等因子相同,与空气相对湿度(RH)、胞间CO2浓度(Ci)等相反;其光饱合点超过2000μmol.m 2s 1,最大净光合速率达22μmol.m 2s 1,暗呼吸速率为1.34μmol.m 2s 1,CO2补偿点为0.97μmol.mol 1,光补偿点为22.2μmol.m 2s 1,羧化效率为0.2539μmol.m 2s 1,表观光量子效率高达0.0592μmol.mol 1;表明地毯草是一种具有较强耐荫性的C4型阳性的暖季型草坪草,除了在园林中可以广泛用作草坪地被外还可以在一些较荫湿的特殊地带作为绿化和防护之用。

The photosynthetic characteristics in leaves of carpet grass-Axonopus compressus

Carpet grass Axonopus compressus is a typical warm season turf. A field study on the photosynthetic characteristics in the leaves of carpet grass was made using a Li 6400 portable photosynthetic system. With a one peak diurnal pattern the photosynthesis has no middle day depression and belongs to the non stomatal limitation type. Its pattern reaches peak value at about 14∶00, and changes positively with the variations of photosynthetic active radiation, air temperature, transpiration rate, but negatively with those of relative humidity of air, internal CO2 concentration. The light saturation point is above 2 000 μmol.m 2s 1, with the maximum net photosynthetic rate higher than 22 μmol.m 2s 1, dark respiration rate at 1.34 μmol.m 2s 1, CO2 compensation point at 0.97 μmol. mol 1, light compensation point at about 22.2 μmol.m 2s 1, carboxylation efficiency at 0.253 9 μmol.m 2s 1,and apparent quantum yield at 0.059 2 μmol. mol 1. These results indicate that carpet grass is a C4 type, shade tolerant and heliophylic warm season turf species and it can be widely used in gardening and some shady and humid places for virescence and protection.