氮钾肥对盐胁迫下面包果光合作用和抗氧化系统的影响

Effects of nitrogen and potassium fertilizer on photosynthesis and antioxidant system of breadfruit under salt stress

研究氮钾营养对盐胁迫下面包果光合作用、叶绿素荧光和抗氧化系统的影响,为滨海盐碱地的面包果耐盐栽培提供参考。以面包果[Artocarpus altilis(Parkinson)Fosberg]为试验材料,采用土培法,浇灌盐分浓度为10.2 g/kg的海水,处理设置为低氮低钾(N_(1)K_(1)+S)、低氮中钾(N_(1)K_(2)+S)、中氮低钾(N_(2)K_(1)+S)、中氮中钾(N_(2)K_(2)+S)、无氮无钾浇海水阳性对照(N_(0)K_(0)+S)以及无氮无钾浇灌溉水阴性对照(N_(0)K_(0)+W)。结果表明:低氮低钾处理较单盐胁迫增加了面包果叶片净光合速率(Pn)、气孔导度(Gs)、胞间CO_(2)浓度(Ci)、蒸腾速率(Tr)以及潜在最大光能转换效率(Fv/Fm)、电子传递效率(ETR)和光系统Ⅱ活性(Fv/Fo),而高浓度养分添加降低了胁迫下面包果的光合能力。与阴性对照相比,单盐胁迫处理和低氮低钾处理的叶片过氧化物酶(POD)、过氧化氢酶(CAT)和超氧化物歧化酶(SOD)活性呈增加趋势。施肥还降低了叶片中的丙二醛(MDA)含量。施肥及其与MDA含量之间的交互作用对面包果叶片光合作用的影响较大。低浓度的氮钾养分添加可以通过增强叶片光合作用和抗氧化酶系统来减轻盐胁迫对植物生长的有害作用。

The effects of nitrogen and potassium nutrition on plant photosynthesis,chlorophyll fluorescence and antioxidant systems of breadfruit(Artocarpus altilis)under salt stress were investigated to provide a reference for salt-tolerant cultivation of breadfruit in coastal saline-alkali land.Breadfruit[Artocarpus altilis(Parkinson)Fosberg]was selected and cultivated in the soil.The sea water solution was applied at the concentration of 10.2 g/kg.Breadfruit seedlings were divided into six groups and treated as follows:seedlings amended with low level of nitrogen and potassium(N_(1)K_(1)+S);seedlings amended with low level of nitrogen and medium level of potassium(N_(1)K_(2)+S);seedlings amended with medium level of nitrogen and low level of potassium(N_(2)K_(1)+S);seedlings amended with medium level of nitrogen and potassium(N_(2)K_(2)+S);seedlings cultured in Hoagland nutrient solution(-N,-K)with 10.2 g/kg salt concentration(N_(0)K_(0)+S);seedlings cultured in Hoagland nutrient solution(-N,-K)with tap water(N_(0)K_(0)+W).The results showed that nitrogen and potassium at lower concentrations increased the net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO_(2) concentration(Ci)and transpiration rate(Tr),as well as the maximum photosynthetic efficiency of PSII(Fv/Fm),electron transport rate of PSII(ETR)and activity of PSII(Fv/Fo),while higher concentrations reduced the effects or even exacerbated the occurrence of photosynthetic capacity in stressed plants.The activities of antioxidant enzymes such as peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)increased in salt-only treatment,and induced the increase of the activities of these enzymes at low concentrations of nitrogen.Fertilization also reduced malonaldehyde(MDA)contents.Fertilizer and the interaction between it and MDA content explained a greater portion of the variation of photosynthesis.Nitrogen and potassium at a low concentration could alleviate the detrimental effects of salt stress on plant growth by increasing photosynthetic efficiency and enhancing antioxidant enzyme systems in leaves.