Plants must carefully coordinate their growth and development with respect to prevailing environmental conditions. To do this, plants can use a range of nutritional and non‐nutritional information that allows them to proactively modulate their growth to avoid resource limitations. As is well‐known to gardeners and horticulturists alike, substrate volume strongly influences plant growth, and maybe a key source of non‐nutritional information for plants. However, the mechanisms by which these substrate volume effects occur remain unclear. Here, we show that wheat plants proactively modulate their shoot growth with respect to substrate volume, independent of nutrient availability. We show that these effects occur in two phases; in the first phase, the dilution of a mobile ‘substrate volume‐sensing signal’ (SVS) allows plants to match their shoot (but not root) growth to the total size of the substrate, irrespective of how much of this they can occupy with their roots. In the second phase, the dilution of a less mobile ‘root density‐sensing signal’ (RDS) allows plants to match root growth to actual rooting volume, with corresponding effects on shoot growth. We show that the effects of soil volume and plant density are largely interchangeable and that plants may use both SVS and RDS to detect their neighbours and to integrate growth responses to both volume and the presence of neighbours. Our work demonstrates the remarkable ability of plants to make proactive decisions about their growth, and has implications for mitigating the effects of dense sowing of crops in agricultural practice.

中文翻译：

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小麦植物感知基质体积和根密度以主动调节芽生长

植物必须根据普遍的环境条件仔细协调它们的生长和发育。为此，植物可以使用一系列营养和非营养信息，使它们能够主动调节生长以避免资源限制。园丁和园艺家都知道，基质体积强烈影响植物生长，并且可能是植物非营养信息的关键来源。然而，这些底物体积效应发生的机制仍不清楚。在这里，我们表明小麦植物主动调节相对于底物体积的芽生长，而与养分可用性无关。我们表明这些影响发生在两个阶段；在第一阶段，移动“基质体积感应信号”（SVS）的稀释使植物能够将它们的芽（但不是根）的生长与基质的总大小相匹配，而不管它们的根可以占据多少。在第二阶段，流动性较低的“根密度感应信号”（RDS）的稀释使植物能够将根生长与实际生根体积相匹配，从而对枝条生长产生相应的影响。我们表明土壤体积和植物密度的影响在很大程度上是可以互换的，植物可以同时使用 SVS 和 RDS 来检测它们的邻居，并将生长响应整合到体积和邻居的存在。我们的工作证明了植物对其生长做出积极决策的非凡能力，并且对减轻农业实践中作物密集播种的影响具有重要意义。