Local root growth and death are mediated by contrasts in nutrient availability and root quantity between soil patches

Plants are thought to be able to regulate local root growth according to its overall nutrient status as well as nutrient contents in a local substrate patch. Therefore, root plastic responses to environmental changes are likely co-determined by local responses of root modules and systematic control of the whole plant. Recent studies showed that the contrast in nutrient availability between different patches could significantly influence the growth and death of local roots. In this study, we further explored beside nutrient contrast, whether root growth and death in a local patch are also affected by relative root quantity in the patch. We conducted a split-root experiment with different splitting ratios of roots of Canada goldenrod (Solidago canadensis) individuals, as well as high (5× Hoagland solution vs water) or low (1× Hoagland solution vs water) contrast nutrient conditions for the split roots. The results showed that root growth decreased in nutrient-rich patches but increased in...学界普遍认为，植物可依据自身整体营养状态与局部基质斑块中的养分含量，调控根系的局部生长。因此，植物根系对环境变化的可塑性响应，大概率由根系模块的局部响应与整株植物的系统性调控共同决定。既往研究显示，不同基质斑块间的养分有效性差异，可显著影响局部根系的生长与死亡。本研究进一步探究：除养分差异外，局部基质斑块内的根系相对数量是否也会对该斑块内的根系生长与死亡产生影响。我们以加拿大一枝黄花（Solidago canadensis）单株为材料开展分根实验（split-root experiment），设置不同的根系分根比例，并为分根后的两侧根系设置两种养分差异梯度：高差异组（5倍霍格兰德营养液（Hoagland solution）与无菌水对照）、低差异组（1倍霍格兰德营养液与无菌水对照）。结果表明，养分富集斑块内的根系生长受到抑制，而在……