Effects of 6-BA and amino acid selenium on leaf senescence and endogenous hormones content in grape

WANG Haibo; WANG Shuai; WANG Xiaodi; SHI Xiangbin; WANG Baoliang; ZHENG Xiaocui; WANG Zhiqiang; JI Xiaohao; LIU Fengzhi

doi:10.13925/j.cnki.gsxb.20170027

Abstract：[Objective]The experiment was conducted to clarify the effects of 6-BA and amino acid selenium on grape leaf senescence and to provide a theoretical basis for preventing leaves from early aging.[Methods] Two grape cultivars,‘halia’and‘Centenial’seedless,under protected cultivation for delayed harvest were used for the study.Amino acid selenium and 6-BA were sprayed on the leaves,and spraying clear water was used as the control group (CK).The physiological indexes,such as chlorophyll content,net photosynthetic rate and endogenous hormone contents were determined during leaf senescence.The experiment materials including triennial‘ Italia’ and‘ Centenial seedless’ were planted in key grape technique demonstration orchard of Fruit Research Institute of Chinese Academy of Agricultural Sciences (Xingcheng,Liaoning province east longitude 120°06′,northern latitude 40° 16′).The plants grafted on Beta rootstock were grown in a solar greenhouse.Tree and row spacing was 2.0 m ×0.7 m.A tilt dragon trunk and V form trellis system was adopted with regular managements.Starting from August 1,2013,the vines were sprayed with 50 mg· L-1 amino acid selenium [a patented product (ZL201010199145.0) of Fruit Research Institute of Chinese Academy of Agricultural Sciences containing 3％ Se,produced by An Qiu Xin Hai Biofertilizer Limited Company] or 20 mg· L-1 6-BA at 3:00-4:00 pm every 15 days until 15 days before leaf fall.The experimental treatments were set with 3 replicates,each with 15 trees.The concentrations of amino acid selenium and 6-BA used were based on the results of pre-experiments.Secondly,from September 8th to the end of leaf fall,representative leaf samples from shoots at consistent growth were taken at 8:00 am every half a mouth.20 functional leaves located at the 4th to 8th nodes were collected,put into a curling stone,and brought to laboratory,where they were frozen with liquid nitrogen.Acetone soaking methods was used to extract chlorophylls.A CIRAS-2 portable photosynthesis system was used to measure net photosynthetic rate during a sunny day between 9:00am and 1 1:00am.The measurements were carried out at a light intensity of 1 200 μmol· m-2· s-1,carbon dioxide level of 360 μmol· mol-1 and temperature of 25 ℃.ELISA (enzyme linked immunosorbent assay for detection) was used to measure gibberellin (GA3),zeatin riboside (ZR),auxin (IAA) and abscisic acid (ABA) contents.The ELISA kits were supplied by Crop Chemical Control Research Center,China Agricultural University.Data collected were processed with Excel 2003,and statistic analyses with SPSS 13.0.[Results] Compared with CK,amino acid selenium and 6-BA treatments significantly delayed the decreases in chlorophyll content and net photosynthetic rate.With the increase of treatment times,endogenous ZR and GA3 contents and the ratios of ZR/ABA,GA3/ABA and (ZR + GA3)/ABA increased significantly,while the content of ABA decreased significantly.IAA showed maintained growth in the earlier period but promoted senescence in the later period.Before November 8th,compared with CK,amino acid selenium and 6-BA treatments significantly increased the IAA content in leaves but decreased it later.There were differences in different senescencetypes of grape leaves,the leaves of ‘ Italia’ were slower in senescence with antioxidant enzymes maintaining higher activities at the late growth stage.[Conclusion] Application of amino acid selenium or 6-BA is effective to maintain chlorophyll content and net photosynthetic rate in ‘Italia’ and ‘Centenial seedless’ grapes and changes the hormone levels and balance.The two reagents can delay leaf senescence and to some degree prolong the functional period of leaves.Therefore,amino acid selenium and 6-BA application can be an important pratice to delay leaf aging in grapes under protected cultivation for delayed harvest.