油莎豆幼苗应对盐碱胁迫的光合生理响应机制

对油莎豆幼苗在不同浓度盐胁迫和碱胁迫下的光合生理响应进行研究，揭示其耐盐机制以及抗盐碱能力阈值，为油莎豆在新疆大面积种植及合理划分种植区域提供理论基础。试验选用2种中性盐（NaCl, Na₂SO₄）和2种碱性盐（NaHCO₃ , Na₂CO₃），分别按2∶1的比例配成相应溶液进行胁迫处理，盐、碱胁迫处理低、中、高浓度分别为 80、160、320 mmol· L^-1和40、80、120 mmol· L^-1，培养于室内光温培养箱中，在出苗15 d后，测量叶绿素含量，光合参数，荧光参数等指标。结果表明：在盐、碱胁迫下随胁迫程度的增加叶绿素a含量（Chl a）、叶绿素b含量（Chl b）、总叶绿素含量（Chl T）、类胡萝卜素含量（Car）、光合速率（P_n）、气孔导度 （G_s）、蒸腾速率（T_r）呈下降趋势，最大荧光（F_m）、实际光化学效率（ΦPSⅡ）、最大光化学效率（F_v/F_m）、光化学猝灭系数（qP）被抑制，非调节性能量耗散（Y(NO)）升高。其中P_n与G_s、T_r、Chl a，呈极显著正相关（P<0.01），与Car、Chl T、F_m、ΦPSⅡ、qP（P<0.05）成显著正相关，与Y(NO)表现为显著负相关。因此油莎豆在盐、碱胁迫下光合速率下降主要与G_s、T_r、Chl a的降低有关。且油莎豆在盐碱胁迫下可通过降低G_s、T_r、叶片含水量（WC）和提高水分利用效率（WUE）以及启动热耗散机制来维持水分的供给和光合系统的动态平衡。在不同盐成分处理中表现为同浓度下碱胁迫抑制程度均大于盐胁迫。

Photosynthetic physiological response mechanism of Cyperus esculentus L. seedlings under saline alkali stress

The objective of this study was to explore the photosynthetic physiological responses of Cyperus esculentus seedlings under different concentrations of saline-alkali stress, and to reveal the salt tolerance mechanism and salt-alkali resistance ability, it was expected to provide a theoretical basis for large-scale cultivation and reasonable planting areas division of C. esculentus in Xinjiang. Two kinds of neutral salts (NaCl and Na₂SO₄) and two alkaline salts (NaHCO₃ and Na₂CO₃) were used to prepare the corresponding solution at the ratio of 2:1 for stress treatment. The low, medium and high concentrations were 80, 160, 320 mmol·L^-1 and 40, 80, 120 mmol·L^-1, respectively for salt and alkaline stress treatments. The chlorophyll content, photosynthetic parameters and fluorescence parameters were measured after 15 days of seedling emergence. The results showed that the contents of chlorophyll a (Chl a), chlorophyll b (Chl b), total chlorophyll (Chl T), carotenoid content (Car), net photosynthesis (P_n), stomatal conductance (G_s) and transpiration rate (T_r) were decreased, while the maximum fluorescence (F_m), actual photochemical efficiency (ΦPSⅡ) , maximal photochemical efficiency (F_v/F_m) and photochemical quenching coefficient (qP) were inhibited, and non regulatory energy dissipation (Y(NO)) was increased with the stress degree increasing. We observed that P_n positively correlated with G_s, T_r, Chl a (P<0.01), and with Car， Chl T， F_m， ΦPSⅡ， qP at 0.05 level， but negatively correlated with Y(NO). These results suggested that the main reason of the decrease of photosynthetic rate under saline-alkali stress is related to the decrease of G_s, T_r and Chl a. Moreover, the dynamic balance of water supply and photosynthetic system could be maintained by reducing G_s, T_r, leaf water content (WC), increasing water use efficiency (WUE) and initiating heat. There was higher inhibition degree of alkaline stress than that of salt stress at the same concentration.