To explore potential effects of soil nutrient on leaf thermal tolerance across geographical origins, five provenance, i.e., Chengbu of Hunan (CB), Zigui of Hubei (ZG), Neixiang of Henan (NX), Lincheng of Heibei (LC) and Pinggu of Beijing (PG), seedlings of Quercus variabilis were cultivated under nitrogen and phosphorus addition. Leaf thermal tolerance parameters (cold, heat and span), nutrient concentrations (nitrogen and phosphorus), nitrogen use efficiency (NUE) and phosphorus use efficiency (PUE), as well as non-structural carbohydrate (soluble sugar and starch) concentrations were analyzed. The results were shown as follows: Nutrient absorption and utilization efficiency varied between oak origins with no obvious geographical trends. PG had higher nutrient use efficiency (NUE and PUE), whereas NX had lower PUE under all treatments. CB had the highest PUE under phosphorus addition. Compared with the control, nutrient addition increased the cold tolerance of PG and LC, and to some extent, increased the heat tolerance of the three middle provenances (ZG, NX, LC). However, the thermal span was opposite to the cold tolerance, as nutrient addition decreased the thermal span of PG and LC but increased that of NX. The leaf cold tolerance had significantly positive correlation with soluble sugar concentration, while the heat tolerance negatively and positively correlated with leaf phosphorus and ratio of nitrogen to phosphorus, respectively. No significant correlation was found between leaf thermal span and leaf chemical substances. To sum up, nutrient use efficiency varying in provenances might be contributed by the original habitats and consequently presented with some local adaptation characteristics, which complicated the response of thermal tolerance to nutrient addition.
通过氮磷添加控制试验,对湖南城步(CB) 、湖北秭归(ZG)、河南内乡(NX)、河北临城(LC)和北京平谷(PG)5个种源的栓皮栎1年生幼苗的叶片温度耐性指标(耐寒性、耐热性及耐温范围)及相关生理指标(叶片养分浓度、非结构性碳水化合物及其组分和养分利用效率)进行测定,研究养分对植物种内不同地理种源的温度耐性影响.结果表明:不同种源的栓皮栎养分吸收与氮磷利用效率对氮磷添加存在显著差异但地理趋势不明显.PG在N、P及其二者复合添加的情况下均具有较高的氮磷利用效率,NX则在不同处理下磷利用效率均处于最低水平,CB在磷添加的情况下对磷的利用效率最高.与对照相比,养分(N、P或NP)添加能明显增加PG和LC的耐寒性,但N添加降低了NX的耐寒性.同时,养分添加在一定程度上增加了ZG、NX和LC的耐热性.耐温范围与耐寒性相反,表现为养分添加降低了PG和LC的温度耐受范围, 而增加了NX的温度耐受范围.偏相关分析表明,耐寒性与叶片可溶性糖浓度呈显著正相关;耐热性与叶片P呈显著负相关,与N/P呈显著正相关;叶片耐温范围与叶片物质浓度无显著相关性.因此,不同地理种源对养分利用程度及其效率可能与源生地土壤环境条件有关,表现出一定的局域适应特征,从而增加了温度耐性对养分响应的复杂程度.
Keywords: Quercus variabilis; non-structural carbohydrate; nutrient; provenance; thermal tolerance.