Differences in Photosynthesis and Plant Growth of 26 Woody Species at the Oil Shale Waste Dump

Abstract:

Photosynthesis-light response and growth feature were compared among 26 woody plants of over 4 years grown at the oil shale waste dump in Maonan district of Maoming city, Gnangdong Province. A remarkable difference was found in maximum net photosynthetic rate （Pmax）, apparent quantum yield （AQY）, instantaneous light utilization efficiency （ILUE）, plant height and diameter at breast height （DBH） among the tested species. According to growth and photosynthesis features, the trees were divided into 1） the fast-growing plants with the average DBH value of 9.44±2.23 cm, the average Pmax of 18.44± 1.38 μmol m^-2s^-1, ILUE of 1.11±0.68% and AQY of 0.0474±0.007 μmol CO₂ μmol^-1 quantum; 2） the moderate-growing plants with the above values of 5.09±0.90 cm, 11.54±1.01 μmol m^-2s^-1, 0.75±0.12% and 0.0406±0.004 μmol CO₂ μmol quantum, respectively; and 3） the slow-growing plants with above values dropping to 2.03 ±0.65 cm, 6.71 ±2.82 μmol m^-2s^-1 0.47±0.12 % and 0.0318±0.006 μmol CO₂ μmol^-1 quantum, respectively. The statistic analysis showed a very significantly positive relationship between ILUE and Pmax or DBH, and plant height also positively correlated with DBH and the total leaf area per plant. The results indicated that photosynthesis-light response curve and ILUE are useful to estimate the adaptation of plants to their habitat. Owning to higher ILUE, growth rates and water use efficiency, the woody species suitable for the restoration of the oil shade waste dump are as follows, Acacia auriculiformis, Bombax malabaricum, Erythrina indica, Terminalia bellirica, Tristania conferta, Ormosia pinnata, Cassia siamea, Samanea saman, Schima wallichii, Syzygium cumini.[