Effect of Exogenous Salicylic Acid on Photosynthetic Characteristics and Aluminum Tolerance of Helianthus tuberosus Under Aluminum Stress
A solution culture experiment was conducted to study the effects of exogenous salicylic acid (SA) (foliage spraying of 500 μmol/L SA) on growth characteristics,photosynthetic characteristics,antioxidant enzyme activity and aluminum (Al) tolerance of 2 Jerusalem artichoke (Helianthus tuberosus) cultivars,Nanjing (Al-resistant genotype) and Ziyang (Al-sensitive genotype) Jerusalem artichoke,under Al stress.The results showed that after growing under 50 μmol/L Al stress for 21 days,seedings of both Helianthus tuberosus cultivars were negatively affected and their plant height,root length,fresh shoot weight,chlorophyll content,maximum light energy conversion efficiency (Fv/Fm),maximum fluorescence yield (Fm) and electron transport rate (ETR) significantly lowered.SOD,POD and CAT of 2 Helianthus tuberosus cultivars showed opposite trends,indicating the differences in Al tolerance of the 2 cultivars,while initial fluorescence (Fo),soluble protein content,superoxide (O2-) production rate,free proline content (Pro) and MDA of the 2 cultivars of Helianthus tuberosus all increased.Spraying salicylic acid (SA) of 500 μmol/L greatly improved the root length,fresh shoot weight,chlorophyll content and fluorescence indexes,and antioxidant enzyme activity,but reduced the O2-production rate.And the contents of soluble protein,free proline (Pro) and MDA also showed increasing trends.Through using grey correlation analysis,we found that spraying SA caused significant effects on chlorophyll b,Fm and ETR of Helianthus tuberosus.The results of subordinate function analysis indicated that by increasing antioxidant enzyme activity and photosynthesis,spraying 500 μmol/L SA every day alleviated the damage to Helianthus tuberosus seedings caused by Al stress and enhanced the resistance of Helianthus tuberosus to Al stress.
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