盆栽试验中外源NO对干旱胁迫下烤烟光合日变化和营养元素含量的影响

Effects of exogenous NO on diurnal variation of photosynthesis and nutrition elements of drought-stressed flue-cured tobacco in pot experiment

为揭示一氧化氮(NO)对干旱胁迫下烤烟耐旱性影响的内在机制,采用盆栽试验研究了NO供体硝普钠(Sodium nitroprusside,SNP)在干旱胁迫条件下对烤烟叶绿素含量(质量分数)、光合日变化、光合同化产物和营养元素含量(质量分数)的影响。结果表明,干旱胁迫下烤烟叶绿素(Chl)含量显著下降,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)明显降低,胞间CO_2浓度(Ci)明显升高,烟株出现光合"午休"现象,同时可溶性糖和蔗糖含量显著增加,淀粉含量下降,P、Ca、Mg、Fe和Mn含量显著降低,N、K含量显著增加,但对B、Zn和Cu影响不大;外源SNP(0.25mmol/L)使干旱胁迫下烤烟Chl显著增加,Pn、Gs、Tr明显提高,Ci明显降低,光合"午休"现象消失,可溶性糖含量进一步提高,但蔗糖含量显著降低,淀粉的分解减少。同时NO能提高干旱胁迫下烤烟叶片中P、K、Ca、Mg、Fe和Mn含量。因此,外源NO能在一定程度上缓解干旱胁迫对烤烟光合同化能力和营养元素吸收的不利影响,提高烤烟的耐旱性。

To reveal the mechanism of nitric oxide（NO） on drought tolerance of flue-cured tobacco under drought stress, a pot experiment was carried out to study the effects of sodium nitroprusside（SNP, an exogenous NO donor） on the chlorophyll content, diurnal variation of photosynthesis, photosynthetic products and nutrient element contents of flue-cured tobacco under drought stress. The results showed that under drought stress, the chlorophyll（Chl） content in flue-cured tobacco significantly decreased. The net photosynthetic rate（Pn）, stomatal conductance（Gs） and transpiration rate（Tr） was reduced, while the intercellular CO2 concentration（Ci） increased with apparent midday depression of photosynthesis. Simultaneously, the contents of soluble sugar, sucrose,N,and K significantly increased, and the contents of starch, P, Ca, Mg, Fe and Mn significantly reduced. In addition, the contents of B, Zn and Cu were changed slightly. Under drought stress, the application of exogenous SNP（0.25mmol/L） significantly increased the Chl content in flue-cured tobacco,promoted the Pn, Gs and Tr, and decreased its Ci content. The midday depression of photosynthesis suppressed.The contents of soluble sugar, P, K, Ca, Mg, Fe and Mn raised, however, the sucrose content was significantly reduced, and starch decomposition diminished. Therefore, the exogenous NO could alleviate the adverse effects of drought stress on the capacity of photosynthetic assimilation and the nutrient element absorption of fluecured tobacco and improve its drought tolerance to a certain extent.