不同氮素水平对红厚壳幼苗生长及光合特性的影响

采用温室盆栽方法,设置0(对照)、50、100、150、200、300、400、600 mg.株-18个氮素处理,研究氮素供应对红厚壳幼苗生长及光合特性的影响。结果表明:随供氮量的增加,红厚壳幼苗高、地径、叶面积及整株生物量均呈现出先增加后降低的趋势,均在200 mg.株-1时达到峰值,分别为22.06 cm、0.65 cm、327.27 cm2和10.43 g.株-1,是对照的1.59、1.25、2.58、1.90倍;地下生物量N5显著高于N7、N8处理,但与其余处理无显著性差异,根冠比随供氮量的增加呈现单调递减趋势;红厚壳幼苗叶绿素a、b及总量随供氮量的增加而增加;红厚壳幼苗的净光合速率、气孔导度、胞间CO2浓度以及蒸腾速率随供氮量的增加呈现出先增加后减小的趋势,均在200 mg.株-1时达最大值,分别是7.29μmol.m-2.s-1、0.071 mol.m-2.s-1、220.22μmol.mol-1和1.34 mmol.m-2.s-1,分别是对照的2.26、1.92、1.37、1.79倍,不同氮素处理间红厚壳光合气体交换参数差异均显著。结果表明:施氮量200 mg.株-1左右为红厚壳幼苗温室栽培的最佳施肥量。

Effects of Nitrogen Application on the Growth and Photosynthetic Characteristics of Calophyllum inophyllum Seedlings

A greenhouse pot experiment was conducted to study the growth and photosynthetic characteristics of Calophyllum inophyllum L.seedlings under different nitrogen fertilization levels(0,50,100,150,200,300,400,and 600 mg·seedling-1).It was indicated that the height,ground diameter,leaf area and biomass of C.inophyllum L.seedlings increased as the nitrogen fertilization increased from 0 to 200 mg·seedling-1 and then decreased with the nitrogen fertilization increased from 200 to 600 mg·seedling-1.The maximum values were 22.06 cm,0.65 cm,327.27 cm2 and 10.43 g·seedling-1,which were 1.59,1.25,2.58,and 1.90 times that of the CK respectively.For underground biomass,N5 was significantly higher than N7,N8,but there was no significant difference among the rest treatments.The root shoot ratio decreased with the nitrogen fertilization increased;Chlorophyll a,chlorophyll b and total chlorophyll increased with the nitrogen fertilization increased;The net photosynthetic rate,stomatal conductance,intercellular CO2 concentration and transpiration rate of C.inophyllum L.seedlings increased as the nitrogen fertilization increased from 0 to 200 mg·seedling-1 and then decreased with the nitrogen fertilization increased from 200 to 600 mg·seedling-1.The maximum values were 7.29 μmol·m-2·s-1,0.071 mol·m-2·s-1,220.22 μmol·mol-1and 1.34 mmol·m-2·s-1,which were 2.26,1.92,1.37 and 1.79 times that of the CK respectively.Statistical analysis indicated that the photosynthetic gas exchange parameters reached significant difference under different nitrogen treatments.Based on these data,it could be concluded that 200 mg·seedling-1 would be the optimal nitrogen amount for C.inophyllum L.seedlings in greenhouse.