Abstract:

In order to explore the growth and physiological and biochemical responses of the peach self-rooted rootstock under NaCl stress and determine the salinity tolerance threshold， the cutting seedlings of one-year-old 5 rootstocks were treated with different NaCl contents （0.2%， 0.4% and 0.6% NaCl）. The results showed that， with the increase of NaCl content， the activity of superoxide dismutase （SOD） and content of malondialdehyde （MDA） increased. With the increase of NaCl content， the activity of peroxidase （POD） increased first and then decreased in Li 1 and Li 3， while decreased first and then increased in Li 5 and GF677， and showed increasing trend in RA. With the increase of NaCl content， the activity of catalase （CAT） showed increasing trend in Li 1， Li 3 and RA， showed decreasing trend in Li 5， and increased first and then decreased in GF677. The content of Pro increased in Li and RA， decreased first and then increased in Li 3 and Li 5， and increased first and then decreased in GF677. The content of soluble sugar increased in Li 3 and Li 5， increased first and then decreased in Li 1 and RA， and decreased first and then increased in GF677. The correlation analysis showed that Na⁺ content was positively related to NaCl content in media， while K⁺ content was negative correlation with NaCl content. The Na⁺/K⁺ was the highest in Li 1， while was the lowest in GF677. Under NaCl stress， the chlorophyll synthesis of 5 peach rootstocks was significantly inhibited. Fluorescence kinetic parameters and light energy absorption， capture and transfer parameters were reduced， and the curve of OJIP changed with the decrease of J， I， P phases and ΔK<0. Considering net photosynthetic rate （P_n） as a tolerance index， the salt tolerance thresholds of Li 1， Li 3， Li 5， RA and GF677 were 0.37%， 0.43%， 0.38%， 0.46% and 0.49% NaCl， respectively. According to comprehensive membership function， salt tolerance coefficient index and salt tolerance thresholds resistance， the salt tolerance showed GF677>RA>Li 3> Li 5>Li 1.In summary， self rooting stocks of peach adapted to salt stress mainly through active oxygen scavenging and osmotic adjustment mechanisms， rootstocks with high salt tolerance could better stabilize the photosynthetic reaction center and alleviate the damage of salt stress to their photosynthetic system， which provided theoretical support for revealing the mechanism of salt tolerance and screening the varieties of peach rootstock with high salt tolerant.

Key words: peach rootstock, salt stress, fluorescence characteristic, physiological biochemistry

摘要：

为研究NaCl胁迫下桃自根砧生长及生理生化指标变化，确定桃自根砧耐盐阈值，选择苗龄为1年的樱桃李（Prunus cerasifera Ehrhart）1号（李1）、樱桃李3号（李3）、樱桃李5号（李5）、RA （Prunus cerasifera Ehrhart）和GF677（Prunus dulcis Mill.×Prunus persica）桃砧木扦插苗为试材进行NaCl处理（质量体积分数0.2%、0.4%和0.6%NaCl）试验。结果表明，随着基质中NaCl含量的增加，5种桃砧木扦插苗的超氧化物歧化酶（superoxide dismutase，SOD）活性和丙二醛（malondialdehyde，MDA）含量均呈上升趋势；过氧化物酶（peroxidase，POD）活性在李1、李3中先升后降，在李5、GF677中则相反，在RA中呈上升趋势；过氧化氢酶（catalase，CAT）活性在李1、李3、RA中呈上升趋势，在李5中呈下降趋势，在GF677则先升后降。脯氨酸（proline，Pro）含量在李1和RA中呈上升趋势，在李3和李5中先降后升，在GF677中先升后降。可溶性糖含量在李1、RA中先升后降，在李3和李5中呈上升趋势，在GF677中先降后升。相关性分析表明，Na⁺水平与基质中NaCl含量成正相关，而K⁺水平则与其呈负相关关系。李1的Na⁺/K⁺最大，GF677最小。在NaCl胁迫下，5种自根砧叶绿素合成明显受到抑制，荧光动力学参数以及光能吸收、捕获和传递参数均降低，快速叶绿素荧光诱导曲线（OJIP）发生变化，其中J、I、P 相降低，且ΔK小于0。以净光合速率为指标，李1、李3、李5、RA和GF677的耐盐性阈值分别为0.37%、0.43%、0.38%、0.46%和0.49% NaCl。综合隶属函数、耐盐系数及耐盐阈值，砧木耐盐性从高到低表现为GF677>RA>李3>李5>李1。综上所述，5种桃自根砧主要通过活性氧清除和渗透调节机制来适应盐胁迫，耐盐性高的砧木能较好地稳定光合反应中心，缓解盐胁迫对其光合系统的伤害。以上结果为揭示耐盐机理及桃耐盐砧木品种的筛选提供理论支撑。

关键词: 桃自根砧, 盐胁迫, 荧光特性, 生理生化