【摘要】 以贝壳堤岛的建群种4年生酸枣为材料,模拟贝壳砂生境系列水分梯度,采用基于茎热平衡法的Dynamax包裹式茎流计和CIRAS-2光合作用仪,测定分析酸枣树干液流及光合特性对土壤水分的响应特征。结果表明:贝壳砂生境酸枣树干液流及叶片光合参数对土壤水分具有阈值响应。酸枣树干液流速率、日累积液流量及树干液流密度均随土壤水分的减小先升高后降低,在土壤相对含水量(Wr)为61.6%时,日液流量达到最高值95.91 g·d-1,Wr为90.1%和16.5%时的日液流量分别比最高值下降35.7%和94.8%。在高水分条件和干旱胁迫下,酸枣日耗水量均表现为下降趋势,但干旱胁迫比高水分条件更易导致酸枣苗木液流速率及日耗水量下降。各水分条件下,酸枣液流速率日动态呈现具有一定宽度的单峰型,昼夜差异明显,在9:00—15:00形成高峰平台,19:00—5:30树干液流停止。随干旱胁迫的加重,酸枣树干液流启动和达到峰值时间滞后,结束时间提前,日蒸腾作用时间缩短;活跃期由一天中由12.5 h缩短至8.0 h,日蒸腾耗水量明显降低,对干旱胁迫表现出一定的水分生理调节能力和适应性。酸枣叶片净光合速率(Pn)、蒸腾速率(Tr)随Wr的增加先升高后降低,而水分利用效率(WUE)先降低后升高,即低水分和高水分条件下,酸枣叶片光合生产能力低,但表现出高效用水的生理特性。Pn最高值15.07μmol·m-2s-1、Tr最高值8.56 mmol·m-2s-1、WUE最高值4.40μmol·mmol-1分别出现在Wr为61.6%,52.2%和83.3%时。酸枣树干液流及光合参数随Wr的变化表明,贝壳砂生境酸枣表现出一定的耐干旱不耐水湿的特性。更多还原

【Abstract】 The characteristics of stem sap flow and photosynthesis parameters in leaves of four-year-old Ziziphus jujuba var. spinosus,which was grown in shell ridge island,were studied under different soil water regimes with a packaged stem sap flow gauge based on stem-heat balance method and a CIRAS-2 portable photosynthesis system. The objective was to investigate the change pattern of stem sap flow and photosynthesis of leaves of Z. jujuba leaves in response to soil water conditions. The results showed that soil moisture had threshold effect on the stem sap flow and photosynthetic parameters of Z. jujuba. The stem sap flow velocity,diurnal cumulative sap flow flux and sap flow density all increased at first and then decreased with decreasing soil water content. The maximum daily sap flow flux( 95. 91 g·d- 1) was observed at the relative soil water content( Wr) of 61. 6%,and the daily stem sap flow flux decreased by 35. 7% and 94. 8% at a Wrof90. 1% and 16. 5% respectively. The daily water consumption declined under high soil water content and drought stress conditions,while drought stress had a more significant effect on the decrease of stem sap flow velocity and daily waterconsumption than high soil water content. The diurnal changes of stem sap flow velocity showed a wide single-peaked curve under all soil water condition. There were significant differences in stem sap flow between day and night were observed,and the stem slap flow maintained high levels during 9: 00—15: 00 and stopped during 19: 00—5: 30. With aggravation the aggravating of drought stress,stem sap flow started and reached the daily peak value later,and stopped earlier; The daily active time shorter from 12. 5 h to 8. 0 h,implying a shorten daily transpiration period,leading to a decrease of daily transpiration water consumption,which indicated a water physiological adaptability of Z. jujuba to drought stress. The net photosynthetic rate( Pn) and transpiration rate( Tr) in of Z. jujuba leaves increased first and then decreased with increasing Wr,while the water use efficiency( WUE) exhibited a trend opposite to that of Pnand Tr. Namely,under lower and higher water conditions,the photosynthetic production of leaves of Z. jujuba was low,but the water use efficiency was high. The maximum value of Pn( 15. 07 μmol·m- 2s- 1),Tr( 8. 56 mmol·m- 2s- 1),and WUE( 4. 40 μmol·mmol- 1)was observed at an Wrof 61. 6%,52. 2% and 83. 3%,respectively. The changes of stem sap flow and leaf photosynthetic parameters under variant soil water content indicated that Z. jujuba growing in shell sand habitat exhibited a certain tolerance to drought,but not to waterlogging.更多还原