喀斯特石漠化地区四种牧草光合日变化特征研究

Research on diurnal photosynthetic characteristics of four forage grasses in karst rock desertification areas

利用英国Lcpro+光合仪研究了喀斯特石漠化地区白三叶、高羊茅、菊苣、饲用玉米等4种牧草晴天的光合日变化特征。结果表明:在石漠化地区白三叶、高羊茅、菊苣、饲用玉米的净光合速率日均值分别为10.01,6.23,6.16,7.64μmol CO2·m-2·s-1;蒸腾速率日均值分别为5.11,5.44,4.35,3.36 mmol H2O·m-2·s-1;日均水分利用效率分别为1.94,0.98,1.40,2.09μmol CO2·mmol-1H2O。白三叶表现出高光合、高蒸腾的特点,其Pn值在4种牧草中最高,蒸腾速率仅次于高羊茅,水分效率稍低于饲用玉米;高羊茅表现出低光合、高蒸腾的特点,水分利用效率最低;菊苣的净光合速率在4种牧草中最低,蒸腾速率和水分利用效率介于其他3种牧草之间;饲用玉米的净光合速率仅次于白三叶,蒸腾速率最低,水分利用效率最高。从牧草应充分利用石漠化地区稀缺的光能和土壤水分的角度考虑,建议饲用玉米同菊苣、白三叶、高羊茅间作套作,以充分利用光能和土壤水分,增加土壤N素,提高地表覆盖度,减少水土流失。

The diurnal photosynthetic characteristics of Trifolium repens, Festuca data, Cichorium intybus and Zea mays in karst rock desertification areas were determined by British Lcpro ＋ photosynthetic instrument on sunny days. Daily mean value of net photosynthetic rate of Trifolium repens, Festuca data, Cichorium intybus and Zea mays was 10. 01, 6.23, 6.16 and 7.64 μmol CO2·m^-2·s^-1 respectively, the average daily transpiration rate was 5.11 5.44, 4.35 and 3.36 mmol H2O·m^-2·s^-1 daily, respectively, and the water-use efficiency was 1.94, 0. 98, 1.40 and 2. 09 μmol CO2·m^-2·s^-1. The characteristics of Trifolium repens were high in both photosynthetic and transpiration rate, wilose Pn value was the highest in these tour forage grasses. Festuca elata exhibited low photosynthetic rate and high transpiration rate, of which the water-use efficiency was the lowest. Net photosynthetic rate of Cichorium intybus was the lowest. Zea mays exhibited the lowest transpiration rate and the highest water-use efficiency, along with a relatively high Pn value. In order to make full use of scarce light energy and soil moisture content in karst rock desertification areas, it was suggested that Zea mays should be intercropped with Cichorium intybus, Trifolium repens and Festuca clara, and soil nitrogen and ground surface coverage could be increased while the water loss and soil erosion would be reduced consequently.