Department of Ecology and Environmental Science, University of Kuopio, P.O. Box 1627, FIN-70211, Kuopio, Finland.
J Chem Ecol. 1996 Apr;22(4):617-36. doi: 10.1007/BF02033574.
Effects of nitrogen availability on secondary compounds, mycorrhizal infection, and aphid growth of 1-year-old Scots pine (Pinus sylvestris L.) seedlings were studied during one growing season. Seedlings were fertilized with nutrient solutions containing low, optimum, and two elevated (2 × and 4 × optimum) levels of NH4NO3. At the end of growing season foliar nitrogen concentration, needle biomass, needle length, water contents of needles, root collar diameter, and number of buds increased with enhanced nitrogen availability. Addition of nitrogen did not have effect on concentrations of monoterpenes in growing needles, but in mature needles significantly decreased concentrations of some individual and total monoterpenes were detected. In growing needles the concentrations of some individual resin acids decreased, and in mature needles concentrations of some individual and total resin acids increased with increased nitrogen fertilization. Higher numbers of resin ducts were found in mature needles with nitrogen fertilization. Nitrogen fertilization decreased total phenolic concentrations in growing and mature needles of the current year, but in needles of the previous year no significant differences occurred. Mycorrhizal infection was highest at medium (optimum and 2 × optimum) nitrogen fertilization levels. The relative growth rate (RGR) of grey pine aphid [Schizolachnus pineti (F.)] responded positively to the increase in foliar nitrogen content. However, the increase in aphid performance between optimum and the highest fertilization level was slight. This may indicate a deterring effect of resin acids on aphids. The results indicate that carbon/nutrient balance hypothesis fails to predict directly the effects of nitrogen availability on concentrations of carbon-based defensive compounds in mature foliage. Altered nitrogen supply affects allocation to secondary metabolites differently, depending on the developmental state of the plant and the biosynthesis pathway, cost of synthesis, and storage of compounds.
在一个生长季内，研究了氮素供应对 1 年生欧洲赤松（Pinus sylvestris L.）幼苗次生化合物、菌根感染和蚜虫生长的影响。幼苗用含有低、最佳和两种升高（最佳的 2 倍和 4 倍）浓度的 NH4NO3 的营养液进行施肥。在生长季结束时，叶片氮浓度、针叶生物量、针叶长度、针叶含水量、根颈直径和芽数随着氮供应的增加而增加。氮的添加对生长针叶中单萜的浓度没有影响，但在成熟针叶中，检测到一些单萜和总单萜的浓度显著降低。在生长针叶中，一些个体树脂酸的浓度降低，而在成熟针叶中，一些个体和总树脂酸的浓度随着氮施肥的增加而增加。在成熟针叶中发现了更多的树脂管，随着氮施肥而增加。氮施肥降低了当年生和前一年生针叶中的总酚浓度，但在前一年生针叶中没有显著差异。菌根感染在中等（最佳和 2 倍最佳）氮施肥水平下最高。灰松蚜虫（Schizolachnus pineti (F.)）的相对生长率（RGR）对叶片氮含量的增加呈正响应。然而，在最佳和最高施肥水平之间，蚜虫表现的增加是轻微的。这可能表明树脂酸对蚜虫有抑制作用。研究结果表明，碳/养分平衡假说不能直接预测氮供应对成熟叶片中碳基防御化合物浓度的影响。改变氮供应对次生代谢物的分配有不同的影响，这取决于植物的发育状态、生物合成途径、合成成本以及化合物的储存。
