土壤酸度对脂松苗木光合和叶绿素荧光的影响

脂松（Pinus resinosa）是北美东北部地区重要的造林树种之一，2004年在我国东北东部山地引种栽培初步获得成功.为扩大脂松栽培范围，采用盆栽方法研究不同土壤酸度（pH分别为4.5、5.5、6.5、7.5和8.0）对脂松苗木光合和叶绿素荧光参数的影响，确定其适生的土壤酸度范围.结果表明：土壤酸度对脂松苗木针叶叶绿素a、b和叶绿素含量、类胡萝卜素含量、净光合速率(P_n)和荧光参数F_o、F_m、F_v、F_v/F_m、Φ_PSⅡ有显著影响（P<0.05）.pH 5.5处理的叶绿素含量和P_n最高，分别比pH 7.5和8.0 处理增加41%、50%和61%、88%；pH 7.5和8.0处理时最低.pH 5.5时叶绿素荧光参数F_v/F_m和Φ_PSⅡ均最高，分别比pH 7.5和8.0处理增加8%、12%和22%、35%；pH 7.5和8.0时则受到明显抑制.土壤pH值为5.5时最适宜脂松生长.

Effects of soil acidity on Pinus resinosa seedlings photosynthesis and chlorophyll fluorescence

Red pine ( Pinas resinosa) is one of the most important tree species for timber plantation in North America, and preliminary success has been achieved in its introduction to the mountainous area of Northeast China since 2004. In order to expand its growth area in other parts of Northeast China, a pot experiment was conducted to study the adaptability of this tree species to varying soil acidity. P. resinosa seedlings were grown in soils with different acidity (pH =4. 5, 5.5,6. 5, 7.5,and 8. 0) to test the responses of their photosynthesis and chlorophyll fluorescence parameters to soil pH levels, and the appropriate soil acidity was evaluated. Dramatic responses in chlorophyll a and b contents, P_n, and chlorophyll fluorescence parameters (F_o, F_m, F_v, F_v/F_m, and Φ_(PSⅡ) ) were detected under different soil acidity ( P ＜ 0. 05 ), with the highest chlorophyll content and P_n under soil pH 5.5, and significantly lower chlorophyll content and P_n under soil pH 7.5 and 8.0. The chlorophyll content and P_n were 41% and 50%, and 61% and 88% higher under soil pH 5.5 than under soil pH 7.5 and 8. 0. The seedlings had a significant photosynthetic inhibition under soil pH 7. 5 and 8.0, but the highest F_v/F_m and Φ_(PSⅡ) under soil pH 5.5. Comparing with those under soil pH 7.5 and 8. 0, the F_v/F_m and Φ_(PSⅡ) under soil pH 5.5 were 8% and 12%, and 22% and 35% higher, respectively. It was suggested that soil pH 5.5 was most appropriate for P. resinosa growth.