Abstract:

To research the effect of different salt stress on the photosynthesis and the changes in reflectance spectrum characteristics of cherry rootstock seedling， the cherry rootstock ‘Daqingye’ was used as experimental material， and 4 treatments of salt stress were set according to 0， 75， 150 and 300 mmol·L^-1 NaCl. Using spectrophotometer， CI-340-photosynthesis system and CI-710 leaf spectrometer， the chlorophyll content， photosynthesis and spectrum were measured for studying the changes of indexes in the leaves of cherry rootstock seedlings and the correlation among indexes. The results showed that the net photosynthetic rate （P_n）， transpiration rate （T_r）， stomatal conductance （G_s） and intercellular carbon dioxide concentration （C_i） all increased firstly and then decreased with the increase of salt concentration. The contents of chlorophyll a+b and chlorophyll a showed similar trend with photosynthetic index， while the contents of chlorophyll b decreased with the increase of salt concentration. The contents of 3 chloroplast pigments reached the highest in 75 mmol·L^-1 NaCl treatment. With the change of salt content， the reflectance of cherry rootstock varied in different wavebands， however， the trends of spectral characteristic curves were consistent， and there were one “green peak”， one “red valley” and one reflection platform. The reflectivity in the near infrared and green light region was the highest in 75 mmol·L^-1 NaCl treatment and was the lowest in 150 mmol·L^-1 NaCl treatment. However， in the bands of blue violet and visible red light， the reflectivity of 150 mmol·L^-1 NaCl treatment was the highest. The results indicated that the proper low-salt treatment could promote the photosynthetic pigment content and photosynthesis of the leaves of the cherry rootstock， and the spectral reflectance could also reflect the degree of salt stress of the plant to a certain extent.

Key words: cherry rootstocks, salt stress, photosynthetic response, chlorophyll, spectral reflectance

摘要：

为研究不同盐胁迫对樱桃砧木幼苗叶片光合作用的影响及反射光谱的变化，以樱桃砧木大青叶为试验材料，设置0、75、150和300 mmol·L^-1 NaCl盐胁迫处理，采用分光光度计、CI-340-便携式光合测定仪和CI-710光纤光谱仪测定叶绿素含量、光合及光谱，研究盐胁迫下樱桃砧木幼苗叶片色素含量、光合指标、反射光谱变化及彼此间的关系。结果表明，随着盐含量的增加，叶片净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）和胞间CO₂浓度（C_i）均呈先上升后下降的趋势。叶绿素a+b含量随盐浓度增加呈先升高后降低的变化趋势；其中，叶绿素a含量随着盐浓度增加先升高后降低，叶绿素b含量随着盐浓度增加逐渐降低；在75 mmol·L^-1盐处理下3种叶绿体色素含量达到最高。随着盐含量的改变，樱桃砧木的光谱反射率在不同波段下的变化规律不同，但光谱特征曲线趋势一致，均有1个“绿峰”、1个“红谷”和1个反射平台。在近红外光区和绿光区波段内，反射率在75 mmol·L^-1盐处理时最高，在150 mmol·L^-1盐处理下最低；而在蓝紫光区和可见红光区波段内，反射率在150 mmol·L^-1盐处理下最高。综上所述，适当的低盐处理对樱桃砧木大青叶的光合色素及光合作用均有一定的促进作用，光谱反射率在一定程度上反应了植株受盐胁迫的损伤程度。

关键词: 樱桃砧木, 盐胁迫, 光合响应, 叶绿素, 光谱反射率