生物炭对烟草幼苗氯化钠胁迫的缓解效应

  目的  研究外源添加生物炭对烟苗NaCl胁迫的缓解作用。  方法  以烤烟品种K326为供试材料，通过盆栽试验，施用150 mmol/L NaCl溶液进行盐胁迫，设置0、10、20和30 g/kg生物炭添加量，以不加盐和生物炭为对照（CK），通过检测烟株生物量、水分含量、抗逆生理指标及矿质元素含量等，明确生物炭对烤烟盐胁迫的缓解作用。  结果  盐胁迫导致烟株发育迟缓，叶片含水率降低，自由水与束缚水比值降低，添加20~30 g/kg生物炭可显著提高烟株干鲜重，提高叶片的相对含水率，提高自由水与束缚水的比值。在同一时期，盐胁迫下添加20 g/kg生物炭可显著提高叶片叶绿素a、叶绿素b含量和叶绿素总量；而添加30 g/kg生物炭显著降低了丙二醛（MDA）和H₂O₂含量；同时，盐胁迫增加了叶片超氧化物歧化酶（SOD）和过氧化物酶（POD）活性，加入生物炭后SOD和POD酶活性显著降低。与CK相比，盐胁迫下烟株地上部Ca2+、K+和Mg2+含量分别下降34.36%、15.04%和11.37%，Na+含量增加542.90%，而在移栽后75 d，添加30 g/kg生物炭烟株地上部Ca2+含量增加34.05%，Na+含量降低54.99%。  结论  外源添加生物炭可以改善盐胁迫下烟草叶片水分状况、促进根系发育和烟株生物量积累，缓解由盐胁迫导致的活性氧增多引起的膜脂过氧化反应，调节烟株地上部的离子平衡，本研究中以添加20~30 g/kg生物炭对150 mmol/L NaCl胁迫下烟草生长的缓解效果较好。 

Alleviating effect of biochar on sodium chloride stress in tobacco seedlings

  Objective  This study aims to study the alleviating effect of exogenous biochar on NaCl stress of tobacco seedlings.  Methods  Using flue-cured tobacco K326 as material, pot experiment was carried out by applying 150mmol/L NaCl solution as salt stress and setting biochar addition amount of 0, 10, 20 and 30 g/kg biochar addition amount. Meanwhile, control experiment was carried out by not adding salt and biochar treatment as control (CK). The biomass and moisture content of tobacco, physiological index and the content of mineral elements were detected to clarify the alleviating effect of biochar on salt stress of flue-cured tobacco.  Results  Salt stress resulted in growth retarding of tobacco plant, decreased leaf water content and ratio of free water to bound water. The addition of 20-30 g/kg biochar significantly increased dry fresh weight of tobacco plant, leaf relative water content, and ratio of free water to bound water. In the same period, adding 20 g/kg biochar under salt stress could increase chlorophyll a and chlorophyll b contents and total chlorophyll content significantly in leaves. The addition of 30 g/kg biochar significantly reduced the contents of MDA and H₂O₂. Meanwhile, salt stress increased the activities of SOD and POD in leaves, while the addition of of biochar decreased the activities of SOD and POD significantly. Compared with CK, the content of Ca2+, K+ and Mg2+ under salt stress decreased by 34.36%, 15.04% and 11.37%, respectively, and the content of Na+ increased by 542.90%. After 75 days of transplanting, adding 30 g/kg biochar increased the content of Ca2+ in shoot by 34.05% and decreased the content of Na+ by 54.99%.  Conclusion  Exogenous addition of biochar can improve the water status of tobacco leaves under salt stress, promote the root development and biomass accumulation of tobacco plants, alleviating the membrane lipid peroxidation reaction caused by the increase of reactive oxygen species under salt stress, and regulate the ion balance of tobacco overground parts. In particular, adding 20-30 g/kg biochar had the best mitigation effect on tobacco growth under the stress of 150 mmol/L NaCl.