不同水分和施氮量对催吐萝芙木光合特性和生长的影响

Effect of water and nitrogen on photosynthetic characteristics and growth of Rauvolfia vomitoria

  • 摘要: 在西双版纳干季, 田间试验探讨了水分胁迫下施氮量不施氮、低量施氮(1.25 g·株-1)、高量施氮(3.75 g·株-1)对两年生催吐萝芙木(Rauvolfia vomitoria Afzel.)生长和光合的影响。结果表明: 水分胁迫显著降低了催吐萝芙木叶片相对含水量(LRWC), 但LRWC仍在85%以上, 属于低度水分胁迫, 其最大净光合速率、气孔导度、比叶面积、茎重比以及株高、基径和生物量的相对生长速率均较无水分胁迫时低。水分胁迫下, 低量施氮可使最大净光合速率、蒸腾速率、根重比升高, 使株高、基径和生物量的相对生长速率增加, 从而明显增加最终根产量; 而高量施氮则会增加幼树对干旱的敏感性, 加重干旱对催吐萝芙木光合和生长的抑制作用。水分与施氮量交互作用对催吐萝芙木叶片相对含水量、最大净光合速率、水分利用效率、比叶面积和根重比的影响显著, 表明施氮量对其影响视水分胁迫状况而不同。因此, 为获得催吐萝芙木最大根产量, 应在干季收获期前少量施用氮肥。

     

    Abstract: A field experiment was conducted in Xishuangbanna during the dry season to study photosynthetic and growth characteristics of 2-year-old Rauvolfia vomitoria Afzel. under different water and nitrogen treatments. A well-watered condition and a water-stress condition for the water treatments, along with zero N, low N (1.25 g·plant-1) and high N (3.75 g·plant-1) treatments were used in the study. The results show that leaf relative water content (LRWC), maximum net photosynthetic rate (Pn), stomatal conductance (gs), specific leaf area (SLA), stem mass fraction (SMF) and relative growth rates of height (RGRH), basal diameter (RGRD) and biomass (RGRB) under water-stress condition are lower than those under the well-watered condition. Low N treatment significantly eases water stress induced depression in Pn, RGRH, RGRD and RGRB, and increases transpiration rate (E), root mass fraction (RMF). This significantly enhances root yield (YR) compared with zero N and water stress treatment. High N treatment increases drought sensitivity, aggravating photosynthetic and growth depressions of R. vomitoria. The interaction between N rate and drought significantly affects LRWC, Pn, instantaneous water use efficiency (WUEi), SLA, and RMF. This implies that different N rates have different effects under different water conditions. It is concluded that low nitrogen fertilization rate during dry season in Xishuangbanna maximizes root yield of R. vomitoria.

     

/

返回文章
返回