Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the pre...Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the present study was to elucidate the mechanisms of the formation of the upper elevation limit of non-treeline tree species,Picea jezoensis,and the carbon allocation strategies of the species on Changbai Mountain.We employed the^(13)C in situ pulse labeling technique to trace the distribution of photosynthetically assimilated carbon in Picea jezoensis at different elevational positions(tree species at its upper elevation limit(TSAUE,1,700 m a.s.l.)under treeline ecotone;tree species at a lower elevation position(TSALE,1,400 m a.s.l.).We analyzed^(13)C and the non-structural carbohydrate(NSC)concentrations in various tissues following labeling.Our findings revealed a significant shift in carbon allocation in TSAUE compared to TSALE.There was a pronounced increase inδ^(13)C allocation to belowground components(roots,soil,soil respiration)in TSAUE compared to TSALE.Furthermore,the C flow rate within the plant-soil-atmosphere system was faster,and the C residence time in the plant was shorter in TSAUE.The trends indicate enhanced C sink activity in belowground tissues in TSAUE,with newly assimilated C being preferentially directed there,suggesting a more conservative C allocation strategy by P.jezoensis at higher elevations under harsher environments.Such a strategy,prioritizing C storage in roots,likely aids in withstanding winter cold stress at the expense of aboveground growth during the growing season,leading to reduced growth of TSAUE compared to TSALE.The results of the present study shed light on the adaptive mechanisms governing the upper elevation limits of non-treeline trees,and enhances our understanding of how non-treeline species might respond to ongoing climate change.展开更多
A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On ...A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites.展开更多
为研究不同行距对宽幅精播小麦产量和干物质积累与转运的影响,阐明其高产高效的生理机制,给宽幅精播技术在黄淮海平原的进一步推广提供理论依据和技术支撑,于2017-2019小麦生长季,以‘济麦22’为试验材料,在20 cm (R1)、25 cm (R2)和30 ...为研究不同行距对宽幅精播小麦产量和干物质积累与转运的影响,阐明其高产高效的生理机制,给宽幅精播技术在黄淮海平原的进一步推广提供理论依据和技术支撑,于2017-2019小麦生长季,以‘济麦22’为试验材料,在20 cm (R1)、25 cm (R2)和30 cm (R3) 3个行距下,设置宽幅精播(K)和常规条播(T)两种种植方式,分析不同行距下宽幅精播种植与常规条播种植对小麦旗叶光合特性、干物质积累与分配和旗叶^(13)C同化物分配特性差异。结果表明:在相同种植方式下,R2处理下小麦的旗叶净光合速率,开花期和成熟期干物质积累量,花后干物质在籽粒中的分配量和贡献率,籽粒产量均显著高于行距R1和R3处理;在R2行距下, K处理灌浆期叶面积指数、光合有效辐射截获率和开花后14、21和28d旗叶净光合速率和蒸腾速率显著高于T处理,两年度K处理通过增加穗数和粒重使得籽粒产量较T处理提高8.67%;^(13)C示踪结果显示, R2K处理旗叶^(13)C同化物在籽粒的分配量和分配比例显著高于其他处理;R2K处理开花期和成熟期干物质积累量和单茎质量、开花后干物质向籽粒的分配量和对籽粒的贡献率最高,均显著高于其他处理,获得了最高的籽粒产量。综上所述,行距25 cm、宽幅精播种植方式是本试验条件下小麦高产高效的最佳种植模式。展开更多
基金supported by the National Natural Science Foundation of China(Grant numbers 4237105242271100+3 种基金4197112442371095)the Natural Science Foundation of Jilin Province,China(Nos.YDZJ202201ZYTS483YDZJ202201ZYTS470)。
文摘Understanding the physiological adaptations of non-treeline trees to environmental stress is important to understand future shifts in species composition and distribution of current treeline ecotone.The aim of the present study was to elucidate the mechanisms of the formation of the upper elevation limit of non-treeline tree species,Picea jezoensis,and the carbon allocation strategies of the species on Changbai Mountain.We employed the^(13)C in situ pulse labeling technique to trace the distribution of photosynthetically assimilated carbon in Picea jezoensis at different elevational positions(tree species at its upper elevation limit(TSAUE,1,700 m a.s.l.)under treeline ecotone;tree species at a lower elevation position(TSALE,1,400 m a.s.l.).We analyzed^(13)C and the non-structural carbohydrate(NSC)concentrations in various tissues following labeling.Our findings revealed a significant shift in carbon allocation in TSAUE compared to TSALE.There was a pronounced increase inδ^(13)C allocation to belowground components(roots,soil,soil respiration)in TSAUE compared to TSALE.Furthermore,the C flow rate within the plant-soil-atmosphere system was faster,and the C residence time in the plant was shorter in TSAUE.The trends indicate enhanced C sink activity in belowground tissues in TSAUE,with newly assimilated C being preferentially directed there,suggesting a more conservative C allocation strategy by P.jezoensis at higher elevations under harsher environments.Such a strategy,prioritizing C storage in roots,likely aids in withstanding winter cold stress at the expense of aboveground growth during the growing season,leading to reduced growth of TSAUE compared to TSALE.The results of the present study shed light on the adaptive mechanisms governing the upper elevation limits of non-treeline trees,and enhances our understanding of how non-treeline species might respond to ongoing climate change.
基金This work was supported by the National Natural Science Foundation of China
文摘A ^(13)C-NMR method is presented for a quantitative determination of the respective monomercomposition and sequence distributions in ethylene-1-octene copolymers prepared with supportedtitanium/magnesium catalyst. On the basis of the sequence distributions, the ethylene-1-octenecopolymerization mechanism was studied. It was found that the observed sequence distributions inethylene-1-octene copolymers are satisfactorily predicted by the two-site model M/M,in whichthe copolymerization proceeds according to first-order Markovian statistics at the two differentsites.
文摘为研究不同行距对宽幅精播小麦产量和干物质积累与转运的影响,阐明其高产高效的生理机制,给宽幅精播技术在黄淮海平原的进一步推广提供理论依据和技术支撑,于2017-2019小麦生长季,以‘济麦22’为试验材料,在20 cm (R1)、25 cm (R2)和30 cm (R3) 3个行距下,设置宽幅精播(K)和常规条播(T)两种种植方式,分析不同行距下宽幅精播种植与常规条播种植对小麦旗叶光合特性、干物质积累与分配和旗叶^(13)C同化物分配特性差异。结果表明:在相同种植方式下,R2处理下小麦的旗叶净光合速率,开花期和成熟期干物质积累量,花后干物质在籽粒中的分配量和贡献率,籽粒产量均显著高于行距R1和R3处理;在R2行距下, K处理灌浆期叶面积指数、光合有效辐射截获率和开花后14、21和28d旗叶净光合速率和蒸腾速率显著高于T处理,两年度K处理通过增加穗数和粒重使得籽粒产量较T处理提高8.67%;^(13)C示踪结果显示, R2K处理旗叶^(13)C同化物在籽粒的分配量和分配比例显著高于其他处理;R2K处理开花期和成熟期干物质积累量和单茎质量、开花后干物质向籽粒的分配量和对籽粒的贡献率最高,均显著高于其他处理,获得了最高的籽粒产量。综上所述,行距25 cm、宽幅精播种植方式是本试验条件下小麦高产高效的最佳种植模式。
