Effect Of Exogenous 6-BA On Physiological Characteristics,Yield And Quality Of Peanut Under Waterlogging

The experiment was carried out at the Shandong Agricultural University Agricultural Experiment Station and State Key Laboratory of Crop Biology from 2018 to 2019.The objective of this study was to investigate the effects of flooding stress and spraying exogenous cytokinin on root structure,leaf morphology,physiological characteristics,yield and quality of peanut at different peanut growth stages.Peanut?Shanhua108?was grown in the pot culture experiments with flooding treatment during 10 days at V3,R3,R5,R7 stage,respectively.Exogenous 6-benzyladenine?6-BA?(15 mg�L^-1)were sprayed to the whole plants at a rate of 250 mL�m^-22 after waterlogging.The main findings are as follows:1 Effects of exogenous 6-BA on morphology and physiological characteristics of peanut roots under waterlogging stressWaterlogging significantly reduced root dry weight and root length density in 20-40 and40-60 cm soil layers.Compared with different growth stages,root alcohol dehydrogenase?ADH?,lactate dehydrogenase?LDH?activities and root abscisic acid?ABA?content significantly increased;in addition,malate dehydrogenase?MDH?activities and zeatin+zeatin riboside?ZT+ZR?content reduced under flooding stress at seeding stage.The increase accumulation of ZT+ZR content and the declined of ABA content highly enhance the root respiratory enzyme activity and promote root growth after spraying 6-BA on the leaf surface.2 Effects of exogenous 6-BA on physiological characteristics of peanut leaves under waterlogging stressAfter treatment with flooding,the net photosynthetic rate?P_n?,chlorophyll content?SPAD?,maximum photochemical efficiency?F_v/F_m?,Optical System??PS??Performance Index(PI_ABS),the activity of superoxide dismutase?SOD?,peroxidation?POD?,catalase?CAT?and the content of soluble protein,ZT,ZR and auxin?IAA?in leaves decreased;in addition,and the content of malondialdehyde?MDA?,pro,soluble sugar,ABA in leaves increased.Compared with different growth periods,the indexes of submergence in podding period changed greatly,followed by flowering period,and ripending and seeding period had little effect.After spraying 6-BA,P_n,SPAD,F_v/F_m,PI_ABS,the activity of antioxidant enzymes?SOD,POD,CAT?and the content of Pro,soluble protein,soluble sugar,ZT,ZR,IAA in leaves increased,and the content of MDA and ABA declined.It shows that spraying 6-BA can improve the physiological function of flooded peanut leaves,delay leaf senescence,and alleviate the adverse effects caused by flooding.3 Effects of exogenous 6-BA on peanut yield and yield components under flooding stressThe flooding of peanuts at different stages significantly reduced the yield of pods and seeds.The flooding yield was most obvious at the pod-setting stage,followed by the anthesis stage and the pod-filling stage.Waterlogging during the pod-setting period significantly reduced the number of fruit per plant and the percentage of double kernel fruit,increased the number of kilograms of pod,and reduced the yield by 20.74%?30.43%.Waterlogging at flower needle phase significantly reduced the number of pod per plant and the yield decreased by 16.94%?18.94%.Flooding during the pod-filling period has a greater effect on kernel yield.Spraying 6-BA after flooding can increase the yield of pods and seeds of peanuts.The effects of spraying at the flower needle stage and the pod stage are more obvious,followed by the seedling stage,and spraying at the fruit-filling stage has no significant effect.Spraying at the flower needle stage can increase the number of fruit per plant,double kernel fruit rate,and reduce the number of kilograms of pod;while spraying at the pod stage can increase the number of fruit per plant.4 Effect of exogenous 6-BA on peanut seed kernel quality under flooding stressSubmergence decreased protein content and oleic acid/linoleic acid ratio?O/L?,increased crude fat and soluble sugar content.Compared with different growth stages,the change range of flooding indexes was the largest in pod setting stage,followed by that in full fruit stage and flower needle stage,and the smallest in seedling stage.The protein content and O/L of seed kernel increased and the content of crude fat and soluble sugar reduced after spraying 6-BA.Compared with different growth stages,the effect of spraying at pod setting stage and flower needle stage was the most obvious,followed by spraying at full fruit stage,and spraying at seedling stage had little effect on seed quality.