The Waite Research Institute and The School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA, 5064, Australia; School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK.
The Waite Research Institute and The School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA, 5064, Australia; The Plant Accelerator, University of Adelaide, Waite Campus, PMB1, Glen Osmond, SA, 5064, Australia.
Plant Sci. 2020 Jan;290:110146. doi: 10.1016/j.plantsci.2019.05.009. Epub 2019 May 15.
Current climate change models project that water availability will become more erratic in the future. With soil nitrogen (N) supply coupled to water availability, it is important to understand the combined effects of variable water and N supply on food crop plants (above- and below-ground). Here we present a study that precisely controls soil moisture and compares stable soil moisture contents with a controlled wetting-drying cycle. Our aim was to identify how changes in soil moisture and N concentration affect shoot-root biomass, N acquisition in wheat, and soil N cycling. Using a novel gravimetric platform allowing fine-scale control of soil moisture dynamics, a 3 × 3 factorial experiment was conducted on wheat plants subjected to three rates of N application (0, 25 and 75 mg N/kg soil) and three soil moisture regimes (two uniform treatments: 23.5 and 13% gravimetric moisture content (herein referred to as Well-watered and Reduced water, respectively), and a Variable treatment which cycled between the two). Plant biomass, soil N and microbial biomass carbon were measured at three developmental stages: tillering (Harvest 1), flowering (Harvest 2), and early grain milk development (Harvest 3). Reduced water supply encouraged root growth when combined with medium and high N. Plant growth was more responsive to N than the water treatments imposed, with a 15-fold increase in biomass between the high and no added N treatment plants. Both uniform soil water treatments resulted in similar plant biomass, while the Variable water treatment resulted in less biomass overall, suggesting wheat prefers consistency whether at a Well-watered or Reduced water level. Plants did not respond well to variable soil moisture, highlighting the need to understand plant adaptation and biomass allocation with resource limitation. This is particularly relevant to developing irrigation practices, but also in the design of water availability experiments.
目前的气候变化模型预测，未来水资源的可获得性将变得更加不稳定。由于土壤氮（N）供应与水的可获得性有关，因此了解可变水和 N 供应对粮食作物（地上和地下）的综合影响非常重要。在这里，我们进行了一项研究，该研究精确控制土壤湿度，并将稳定的土壤湿度与受控的干湿循环进行比较。我们的目的是确定土壤湿度和 N 浓度的变化如何影响小麦的地上和地下生物量、N 吸收以及土壤 N 循环。使用允许精细控制土壤动态湿度的新型重量法平台，我们对小麦植物进行了一个 3×3 的析因实验，实验中设置了三个 N 施用量（0、25 和 75mgN/kg 土壤）和三个土壤湿度处理（两种均匀处理：23.5%和 13%的重量水分含量（分别称为充分供水和水分减少，以及一个在两者之间循环的变量处理）。在三个发育阶段（分蘖期（收获 1）、开花期（收获 2）和早期籽粒牛奶发育期（收获 3））测量了植物生物量、土壤 N 和微生物生物量碳。当与中高 N 结合时，减少供水会促进根系生长。植物生长对 N 的响应比对水的处理更为敏感，高 N 和不添加 N 处理的植物之间的生物量增加了 15 倍。两种均匀的土壤水分处理导致相似的植物生物量，而可变的水分处理导致整体生物量减少，这表明小麦无论是在充分供水还是在水分减少的水平下都更喜欢一致性。植物对可变的土壤湿度反应不佳，这突出表明需要了解植物在资源限制下的适应和生物量分配。这对于开发灌溉实践特别重要，但对于设计水可获得性实验也很重要。
