平茬年限对沙冬青光合特性与比叶面积的影响

【目的】为在理论与技术上解决孑遗植物种质资源的保存与修复,探究沙冬青被平茬后更新恢复生长的机理和策略。【方法】利用Li-6400便携式光合仪测定了不同平茬年限沙冬青的光合生理特性,同时分析了不同平茬年限沙冬青比叶面积(SLA)与光合速率(Pn)、水分利用效率(WUE)的关系,从而更好地解释平茬复壮后植物补偿性生长机理与持续年限。【结果】平茬后沙冬青净光合速率(Pn)和蒸腾速率(Tr)显著提高,且日变化趋势一致,除平茬后恢复1 a的沙冬青为单峰型,其它平茬年限和未平茬(CK)均为双峰型,且均在11:00左右出现最大值,有第二峰值的出现在15:00左右,不同平茬年限沙冬青水分利用效率日变化趋势也呈单峰或者双峰型,但峰值出现的时间存在差异。随着平茬年限的增加,恢复生长的速度减慢,其净光合速率、蒸腾速率和水分利用效率也逐渐降低,日均值的大小顺序均为:平茬后恢复1 a>平茬后恢复3 a>平茬后恢复8 a>未平茬CK。不同平茬年限沙冬青的比叶面积差异性显著(P <0.05),且随着平茬年限的增加,比叶面积不断减小。不同平茬年限沙冬青比叶面积与净光合速率存在显著的正相关关系,与水分利用效率存在显著的负相关关系,随着平茬年限的增加,沙冬青比叶面积与净光合速率、水分利用效率的回归方程斜率均逐渐减小,即植株单位叶面积净光合速率和水分利用效率均逐渐降低。【结论】有必要通过对衰老、干枯的沙冬青进行合理平茬,以促进林分复壮和生长,同时提高生产力,有利于促进荒漠生态系统有效恢复。

Effect of pruning years on photosynthetic characteristic and specific leaf area of Ammopiptanthus mongolicus

【Objective】It is helpful to solve the technical problems of conservation and development of the germplasm resources in theory and technology.The study on the mechanism and strategy of regeneration and restoration of Ammopiptanthus mongolicus after stubble.【Method】The photosynthetic characteristics of A.mongolicus at different pruning years were determined by Li-6400 portable photosynthetic apparatus.At the same time,the relationship between specific leaf area(SLA)of A.mongolicus and the net photosynthetic rate(Pn),water use efficiency(WUE)was analyzed at different pruning years.So it can better explain the compensatory growth mechanism and duration of plants after rejuvenation of stubble.【Result】The diurnal variation of net photosynthetic rate and transpiration rate of A.mongolicus at different pruning years had a bimodal curve excepted one year after rejuvenation pruning of A.mongolicus,which had a single-peak curve.The maximum value appeared around 11:00,and the second peak value appeared around 15:00.The diurnal variation trend of water use efficiency at different pruning years of stubble also showed a single-peak curve or bimodal curve,but the time of peak appeared were differences at different pruning years.With the increase of the pruning years,the recovery growth rate slowed down,and the net photosynthetic rate,transpiration rate and water use efficiency also decreased.The order of the average diurnal variation flowed by one year after rejuvenation pruning>three years after rejuvenation pruning>eight years after rejuvenation pruning>controlled plant.The difference of specific leaf area in different pruning years was significant(P<0.05),and the specific leaf area decreased with the increase of pruning years.There was significant positive correlation between specific leaf area and net photosynthetic rate at different pruning years.However,specific leaf area and water use efficiency(WUE)existed a significant negative correlation relationship.With the increasing pruning years,the slope of regression equation gradually decreased,so net photosynthetic rate and water use efficiency of A.mongolicus gradually reduced.【Conclusion】Therefore,it was necessary to promote stand rejuvenation and growth by reasonably leveling the stubble of aged and dried A.mongolicus,and improving productivity was conducive to promoting effective recovery of desert ecosystem.