Life Sciences Department, Miterani Department of Desert Ecology, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Plant Signal Behav. 2011 Sep;6(9):1356-60. doi: 10.4161/psb.6.9.16444.
Plants are able to discriminately allocate greater biomass to organs that grow under higher resource levels. Recent evidence demonstrates that split-root plants also discriminately allocate more resources to roots that grow under dynamically improving nutrient levels, even when their other roots grow in richer patches. Here, we further tested whether, besides their responsiveness to the direction of resource gradients, plants are also sensitive to the steepness of environmental trajectories. Split-root Pisum sativum plants were grown so that one of their roots developed under constantly-high nutrient levels and the other root was subjected to dynamically improving nutrient levels of variable steepness. As expected, plants usually allocated a greater proportion of their biomass to roots that developed under constantly high resource availability; however, when given a choice, they allocated greater biomass to roots that initially experienced relatively low but steeply improving nutrient availabilities than to roots that developed under continuously-high nutrient availability. Such discrimination was not observed when the roots in the poor patch experienced only gentler improvements in nutrient availability. The results are compatible with the notion that responsiveness to the direction and steepness of environmental gradients could assist annual plants to increase their performance by anticipating resource availabilities foreseeable before the end of their growing season. The results exemplify the ability of plants to integrate and utilize environmental information and execute adaptive behaviours which, until recently, were attributed only to animals with central nervous systems.
植物能够有区别地将更多的生物量分配给在资源水平较高的器官生长。最近的证据表明，分根植物甚至在其他根生长在较肥沃的斑块时，也会有区别地将更多的资源分配给在动态改善养分水平下生长的根。在这里，我们进一步测试了植物是否除了对资源梯度方向的响应外，还对环境轨迹的陡峭度敏感。将豌豆的分根植物种植，使一根根在高养分水平下生长，另一根根在不同陡峭程度的动态改善养分水平下生长。正如预期的那样，植物通常会将更大比例的生物量分配给在资源可用性较高的环境中生长的根；然而，当有选择时，它们会将更多的生物量分配给最初经历相对较低但陡峭改善的养分可利用性的根，而不是在持续高养分可用性下生长的根。当贫瘠斑块中的根只经历较温和的养分可用性改善时，就不会观察到这种差异。这些结果与这样的观点是一致的，即对环境梯度的方向和陡峭度的响应可以帮助一年生植物通过预测其生长季节结束前可预见的资源可用性来提高其性能。这些结果例证了植物整合和利用环境信息并执行适应性行为的能力，直到最近，这些能力只归因于具有中枢神经系统的动物。
