Effects of KNO3 on physiological characteristics of T337 seedlings under NaCl stress
[Objective]To investigate the effects of different concentrations of KNO3 on the physiologi-cal characteristics of T337 seedlings under 100 mmol/L NaCl stress.[Method]Using a potted 2-year-old apple rootstock T337,as the test material,six treatments were established in this experiment,namely CK1(fresh water irrigation),salt stress(CK2),and salt stress + spraying with four concentrations of KNO3[0.1(T1),0.2(T2),0.3(T3),and 0.4mg/L(T4)],and the chlorophyll content,photosynthetic fluores-cence parameters,antioxidant enzyme activities and osmoregulatory substances of the leaves of each treat-ment were measured and evaluated using the chlorophyll content,photosynthetic fluorescence parameters,antioxidant enzyme activities,and osmoregulatory substances of each treatment were determined and com-prehensively evaluated using principal component analysis.[Result]Photosynthetic pigments(Chl a,Chl b,Chl a/b,Chl a+b)in T337 leaves increased with increasing time under salt stress(CK2).Stomatal conduc-tance(Gs),transpiration rate(Tr),net photosynthetic rate(Pn),maximum photochemical efficiency of PS Ⅱ(Fv/Fm),and photochemical quenching coefficient(qP)contents all showed a decreasing trend.Non-photochemical quenching coefficient(qN),initial fluorescence(Fo),intercellular carbon dioxide concentra-tion(Ci),relative conductivity(REC),malondialdehyde(MDA)content,and proline(Pro)showed an in-creasing trend,while superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities first showed an increasing trend and then a decreasing trend.Compared with CK1,all indicators of T337 seed-lings showed different magnitude of changes after salt stress + exogenous KNO3 treatment(T1-T4),and there were obvious concentration effects,and the chlorophyll content,Gs,Tr,Pn,Fv/Fm,qP decreased the least in T3(0.3 mg/L KNO3)-treated leaves,Ci,REC,MDA,qN,Fo.The comprehensive evaluation showed that the effects of each treatment on the characteristics of T337 seedlings were in the following or-der:CK1>T3>T1>T2>T4>CK2.The best effect was achieved by 0.3 mg/L KNO3 treatment to allevi-ate the damage caused by salt stress to T337.[Conclusion]The application of exogenous KNO3 at appropri-ate concentrations can effectively improve the light and ability of T337 seedlings under salt stress,signifi-cantly increase the antioxidant enzyme activities and osmoregulatory substances,and reduce cell membrane permeability,thus achieving the effect of alleviating salt stress,and the best effect of 0.3 mg/L KNO3 treat-ment to alleviate the damage caused by salt stress on T337.
NETL
NSTL
万方数据
