关键词: 黄瓜, CO₂倍增, 干旱胁迫, 非结构性碳水化合物

Abstract: The effects of wind on the morphology, physiology and growth of trees have been a hot topic and difficulty in ecology. Previous studies examined response and adaptation of trees to wind through short-time wind simulation or mechanical stimulation, which cannot reflect the long-term adaptation mechanism of trees in the natural windy environment. To fill such knowledge gap, we measured the concentrations of carbon, nitrogen, phosphorus, potassium, calcium, sodium and magnesium in needles of a 60-year-old Pinus thunbergii forest along a coastalinland gradient, and analyzed the variations of element concentration and stoichiometric characteristics. The results showed that organic carbon concentration in needle on windward of P. thunbergii decreased from inland to coast, the concentrations of nitrogen, phosphorus, potassium, calcium, sodium and magnesium increased (P<0.05), and N∶P ratio remained stable. However, there were no significant differences for these variables on leeward along the coastal-inland gradient, except that calcium and sodium concentrations decreased. Needle stoichiometric characters were significantly different between windward and leeward within 500 m from coastline, and then kept stable over distance. The correlations among windward needle stoichiometry were pervasive, but on the leeward side, only significant relationships between nitrogen and phosphorus and between calcium and sodium existed. Standardized major axis (SMA) fitted between windward and leeward were not different in slope and intercept (P>0.05). In sum, the needle chemical composition of P. thunbergii was significantly affected by wind stress, but the ratio was relatively stable. The needle carbon assimilation function was significantly affected with the increases of sea wind stress. Meanwhile, P. thunbergii improved its tolerance to wind stress by increasing needle nitrogen, phosphorus, potassium, calcium, sodium and magnesium concentrations, which may be an adaptive strategy for P. thunbergii to long term wind stress in natural environment.

Key words: cucumber (Cucumis sativus), doubled CO₂ concentration, drought stress, non-structural carbohydrates.