水分胁迫对四倍体刺槐苗生长和光合作用的影响

刺槐是我国三北地区的主要防护造林树种,尤其是西北干旱、半干旱地区有广泛的种植;但由于当地气候条件的制约,刺槐难于获得生长所需的足够水分[1],生长受到严重抑制,在黄土高原出现了大面积的"小老树"和低劣残次林[2-4],其生态、经济效益都很低.

Effects of Water Stress on Biomass and Photosynthetic Characteristics of Tetraploid Black Locust (Robinia pseudoacacia L.) Clones

Differences in drought tolerance were studied among three strains of black locust (Robinia pseudoacacia L.) clones (one-year-old micropropagated K2, K3 clones and a common diploid clone CK) under simulated natural drought conditions. The experiment was carried out as a randomized complete blocks design. The following physiological variables were examined, biomass and allocation, photosynthetic characteristics, i.e. net photosynthetic rate (Pn), transpiration rate (E), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), instantaneous water use efficiency (WUE_I), and long-term water use efficiency (WUE_L). Results showed that the K2 and K3 had greater biomass, with the K3 displaying favorable ratio of root biomass to shoot and leaf biomass. Net photosynthetic rate (Pn) declined along with Gs, Ci and the ratio intercellular/ambient (Ci/Ca), under increasing drought stress. The decline in photosynthesis was mainly due to stomatal limitation. The K2 and K3 showed higher WUE and Pn than the CK. There were significant differences of drought level on WUE_L, and the WUE_L of K2 and K3 was greater than that of CK. Evaluation based overall physiological characteristics indicates the K2 and K3 are more drought tolerant, which are well adapted to the drought-stricken area of Northwest China.