毛白杨杂种无性系稳定碳同位素值的特征及其水分利用效率

2008年在北京林业大学对9个毛白杨(Populus tomentosa)杂种无性系苗木生长不同时期的叶片、小枝、根的碳同位素δ~(13)C和瞬时水分利用效率WUEi的差异进行研究,分析不同无性系间δ~(13)C与瞬时水分利用效率WUEi的相互关系,目的在于探求δ~(13)C在筛选高水分利用效率毛白杨杂种无性系中的应用价值.结果表明:不同生长时期叶片δ~(13)C值表现为7月<8月<10月<9月,小枝δ~(13)C值表现为8月<9月<10月,叶片δ~(13)C值、小枝δ~(13)C值在不同时期和不同无性系间的差异均达显著水平,无性系间的差异是引起δ~(13)C值变化的主要因素.不同部位碳同位素比值表现为叶片<小枝<根,毛白杨杂种无性系δ~(13)C值在不同部位和无性系间差异均达显著水平,部位间的差异是引起δ~(13)C值变化的主要因素.δ~(13)C值较高的无性系30、83、BL5的WUEi也较高,δ~(13)C值较低的无性系42、26、BT17的WUEi也较低,且不同时期δ~(13)C和WUEi呈较强的正相关,相关系数分别为0.766、0.872、0.675,高δ~(13)C可以作为筛选高WUEi毛白杨的有效指标,且在苗木生长旺盛时期选育能得到更为可靠的结果.

The characteristics of stable carbon isotope and water use efficiency for Populus tomentosa hybrid clones

Our objective was to explore the possibility of stable carbon isotope(δ~(13)C) on selection of Populus tomentosa hybrid clones with high water use efficiency(WUEi). We measured δ13C values and WUEi in leaves, branches, and roots from seedlings of nine different clones, and analyzed the relationship betweenδ~(13)C and WUEi at Beijing Forestry University in 2008. The results showed that δ~(13)C values of leaves were significantly different between clones at different times, so were δ~(13)C values of branches. δ~(13)C values of leaves were highest in September followed by October, August, and July, while δ~(13)C values of branches were highest in October followed by September and August, δ~(13)C values showed significant differences between different Populus tomentosa hybrid clones. It implied that the difference between clones was a major factor to cause the changes of δ~(13)C values. Carbon isotope ratios were also significantly different between different parts of clones. Ratios were highest in roots followed by branches and leaves, The differences between parts in the same period caused changes of δ~(13)C value as the main factor. The clones 30, 83, and BL5 with higher δ~(13)C had higher WUEi, meanwhile, the clones 42, 26, and BT17 with lower δ~(13)C had lower WUEi. It showed positive correlation between δ~(13)C and WUEi(r= 0.766, p =0.016, r= 0.872, p =0.002, r=0.675, p= 0.023). δ~(13)C can be used as an effective indicator to select clones of Populus tomentosa with high water use efficiency, especially for the selection during vigorous seedling growth.