Contribution of root growth responses to leaf traits and relative growth rate of Populus alba under different water-table conditions
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Water-table depth variations alter root growth response and may affect whole-plant growth in arid and semi-arid regions. We examined how root biomass allocation and root morphological traits affect the leaf physiological and morphological traits and whole-plant growth of Populus alba growing under different water tables. We exposed 1-year-old P. alba cuttings to contrasting soil–water conditions via water table changes in a greenhouse for 90 days. We examined relationships among net assimilation rate (NAR) and other growth components obtained from our published data for trees harvested every 30 days. Strongly negative correlations were found between RMR and root morphological traits. Root mass ratio had a strong negative relationship with LMR, and proportion of fine-root biomass per total root biomass was positively correlated with SLA and NAR. Both NAR and leaf area ratio were important determinants of variation in relative growth rate (RGR). Leaf mass ratio (LMR) and specific leaf area (SLA) were positively correlated with RGR; the correlation was stronger in the case of LMR. Along a water-table gradient, negative relationships between root growth responses are likely to indirectly influence RGR through changes in NAR, LMR, and SLA.
KeywordsBiomass allocation Fine-root growth Leaf growth trait Water-table depth Whole-plant growth
We thank Shigeo Katagiri, Faculty of Agriculture, Shimane University, and Mitsuhiro Inoue, Arid Land Research Center, Tottori University, for their helpful comments on this study. We also thank Takeshi Taniguchi, Arid Land Research Center, Tottori University, for discussion and suggestion on the data analysis. We are grateful to two anonymous reviewers for the comments and suggestions on an earlier version of the manuscript.
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