摘要:白术根茎膨大初期对轻度的土壤水分缺失具有一定的耐受性，但是过度干旱会抑制其根茎膨大及成分积累，因此，无损伤诊断该时期白术是否受到干旱胁迫至关重要。本文以2年生白术为试验材料，在根茎膨大初期控制土壤水分，形成不同程度的干旱胁迫，利用UniSpec-SC光谱分析仪测定其光谱反射率，并结合光合色素含量，探讨白术叶片光谱特征对干旱胁迫的响应规律，为利用光谱参数监测白术生长状况提供技术依据。结果显示，随着干旱胁迫程度增加，可见光区域（400～750 nm）白术叶片光谱反射率升高，说明其光能吸收利用能力下降；但在750～1 000 nm的近红外波段，光谱反射率则逐渐平稳，在1 000 nm处，干旱胁迫下的全部叶片反射率均低于对照。微分光谱在680～750 nm间差异明显，并与叶绿素含量在700～750 nm间呈显著相关。同时，大多数光谱参数与色素含量呈显著相关（P < 0.05），尤其类胡萝卜指数（mCRI）、色素归一化指数（PSNDb）、红边位置（λred）、红边幅值（Dλred）、红边面积（Sred）与之呈极显著相关（P < 0.01）。从上述结果可知，微分光谱680～750 nm可作为检测白术是否受到干旱影响的主要监测波段，红边参数、类胡萝卜指数及色素归一化指数可以作为重要指标，快速、准确、无伤害诊断白术受干旱胁迫程度。本研究结果可为应用反射光谱进行白术干旱胁迫程度诊断提供理论依据和技术支持。
关键词:白术/
干旱胁迫/
光谱特征/
光谱反射率/
光合色素/
光谱参数
Abstract:Atractylodes macrocephala Koidz. is a perennial herb belonging to Compositae family, which is fond of cool climate regions. Rhizome dried for over 2 years are used for a series of medicinal functions. It is a top medicinal herb in Zhejiang Province, China. At the early stage of rhizome enlargement, A. macrocephala has a certain tolerance to mild soil drought, but excessive drought can inhibit rhizome enlargement and accumulation of constituent chemicals. Increasing degree of drought stress could slow down growth, inhibit rhizome enlargement and limit yield. In order to provide reference for drought stress control and cultivation of drought-resistant varieties, biennial A. macrocephala were planted under different drought stress. Spectral reflectance of A. macrocephala leaves determined by UniSpec-SC spectrum analyzer and combined with photosynthetic pigment contents were used to explain the response of spectral characteristics under drought stress. The results showed that spectral reflectance increased in the visible region (400-750 nm) with increasing drought stress. This indicated that the absorption and utilization ability of light energy decreased under increased drought stress. However, spectral reflectance gradually stabilized in the near-infrared band 750-1 000 nm. The reflectance of all the leaves under drought stress was lower than that of the control at 1 000 nm. The difference in spectrum of 680-750 nm was significant, which was correlated with chlorophyll content in 700-750 nm. This band could be used to monitor whether A. macrocephala was affected by drought. The contents of photosynthetic pigments increased initially and then decreased with the increased drought stress. It indicated that a suitable degree of drought was good for growth. Most of the spectral parameters were significantly correlated with pigments contents (P < 0.05). Spectral parameters of mCRI, PSNDb, red-edge position (λred), red-edge amplitude (Dλred) and red-edge area (Sred) were significantly correlated with leaf pigments contents (P < 0.01), which could be used to diagnose drought indicators. In summary, differential spectrum of 680-750 nm could be used to detect drought impact on A. macrocephala. Red-edge parameters, carotenoid reflectance indexes and pigment specific normalized difference may be used as indicators to diagnose drought stress degree of A. macrocephala. This conclusion not only provided a reference for the study of high-spectrum plant research, but also provided theoretical basis and technical support for the application of spectrum diagnosis of A. macrocephala in drought stress analysis.
Key words:Atractylodes macrocephala Koidz./
Drought stress/
Spectral characteristics/
Spectral reflectance/
Photosynthetic pigment/
Spectral parameter
PDF全文下载地址:
http://www.ecoagri.ac.cn/article/exportPdf?id=88875b89-0872-4dc0-93db-f28ea83e20b8
