The Research On Tolerance Of Evaluation ADN Control Technology Of Fig Cutivars To Waterlogging

Figs(Ficus carica Linn.)is considered one of the most sensitive trees to waterlogging stress in fruit cultivation.In heavy rainfall area of the southern China,fig often suffers damage of waterlogging because of the frequent and strong rainfall,which is more severely because of the heavy clay soil and the poor drainage during the rapid growth stage.It has been suggested that the orchard water staying 2-4d will cause leaf wlit or abortion of fig plants,which inhibits inhibited fruits formation and therefore yield and quality decrease,and even leading to tree dead.Damage by waterlogging is an important restraining factor for fig development in the southern of China.For this reason,it’s meaningful to understand the waterlogging-tolerance of fig cultivars,and screening the high waterloggging tolerance cultivars,making full use of fig resources,and cultivating directional of the fig cultivars.In this strudy,varieties of fig cuttings were used to study the effect of waterlogging on physiological characteristics and leaf blade ultrastructure and found out the physiological and biochemical mechanisms under waterlogging stress.Meanwhile,study on the mitigative effect of exogenous ALA under waterlogging,not only provided the theoretical basis for the waterlogging tolerance evaluation system of figs,but also provided the technical reference for species selection and effective measures of improve waterlogging resistance.The main results are as follows:1.In order to reveal the adaptability and tolerance of the two fig cultivas under waterlogging,potted-cuttings of the two cultivars were used in the study to compare the effects of waterlogging on leaf relative water content,pigments,antioxidant enzyme activities,reactive oxygen metabolism,malonaldehyde(MDA),proline content,root vigor,chlorophyll fast fluorescence characteristics and leaf ultrastructure under different waterlogging gradient.The results showed that waterlogging significantly reduced the leaf relative water content and pigments of Masui Dauphine,however,the decrease extents of the two paraments in Brownswick were less and the significant difference observed at the end of the experiment.The high level of antioxidant enzyme activities in Brownswick was maintained during the experiment period,whereas,waterloging significantly increase the enzymes in Masui Dauphine at the early stage of the stress and then decreased sharply.The O2-,H2O2,MDA and proline content were obviously increase in the two fig cultivars under waterlogging,however,the level of increase was more in Masui Dauphine.The leaf chlorophyll fast fluorescence characteristics,including prompt fluorescence of OJIP curves,PSI and PSII reaction center activities and photosynthetic capacity indexes of Masui Dauphine were significantly impaired by waterlogging stress.Furthermore,the leaf blade ultrastructure of Masui Dauphine was seriously damaged,but there had no damage of Brownswick.These indicated that Brownswick was the tolerant waterlogging cultivar and Masui Dauphine was the sensitive cultivar.2.The effects of different concentrations(5～20 mg/L)of 5-aminolevulinic acid(5-ALA)pretreatment on leaf physiological characteristics and root respiratory metabolism related enzymes activities of fig cuttings(Ficus carica Linn.cv.Masui Dauphine)were investigated in the present study.Results showed that 5-ALA pretreatment not only reduced the decreasing extent of leaf relative water content and chlorophyll content,increased activities of leaf superoxide dismutase(SOD)and peroxidase(POD),decreased super oxygen anion production rate,malondialdehyde(MDA)and proline content,but also enhanced activities of root malate dehydrogenase(MDH)and ethanol dehydrogenase(ADH),reduced root lactic dehydrogenase(LDH)activity and promoted root activity.The above results together indicate that 5-ALA pretreatment could mitigate the damage effect of waterlogging on fig and therefore improve the flooding tolerance of fig plants.3.In order to evaluate the waterlogging tolerance of fig(Ficus carica Linn.),potted-cuttings of 12 cultivars were used in the study to compare the effects of waterlogging on leaf pigments,antioxidant enzyme activities,reactive oxygen metabolism,malonaldehyde(MDA),proline,soluble protein content and the chlorophyll fast fluorescence characteristics under full flooding condition.The results showed that waterlogging significantly reduced the leaf pigment and soluble protein content of all cultivars,but the superoxide anions,MDA and proline content were significantly improved by the stress;nevertheless,the amplitudes were different dependent upon cultivars.Furthermore,the leaf chlorophyll fast fluorescence characteristics,including prompt fluorescence of OJIP curves,PSI and PSII reaction center activities and photosynthetic capacity indexes of fig cultivars were significantly impaired by waterlogging stress,most of them were closely correlated with waterlogging tolerance.According to the leaf injury index and the correlated physiological parameters under waterlogging,the 12 cultivars were classified into four groups by fuzzy clustering of SPSS20 software,where 102A,105A and 121E were waterlogging tolerant,106A,113C,107B and 112C were medium tolerant,101A,110C and 114C were weak tolerant,and 117D and 118D were sensitive cultivars.