Corteva Agriscience, 7250 NW 62nd Ave, Johnston, IA 50310, USA.
Phenotype Screening Corporation, 4028 Papermill Road, Knoxville, TN 37909, USA.
J Exp Bot. 2021 Jul 10;72(14):5235-5245. doi: 10.1093/jxb/erab231.
Because plants capture water and nutrients through roots, it was proposed that changes in root systems architecture (RSA) might underpin the 3-fold increase in maize (Zea mays L.) grain yield over the last century. Here we show that both RSA and yield have changed with decades of maize breeding, but not the crop water uptake. Results from X-ray phenotyping in controlled environments showed that single cross (SX) hybrids have smaller root systems than double cross (DX) hybrids for root diameters between 2465 µm and 181µm (P<0.05). Soil water extraction measured under field conditions ranged between 2.6 mm d-1 and 2.9 mm d-1 but were not significantly different between SX and DX hybrids. Yield and yield components were higher for SX than DX hybrids across densities and irrigation (P<0.001). Taken together, the results suggest that changes in RSA were not the cause of increased water uptake but an adaptation to high-density stands used in modern agriculture. This adaptation may have contributed to shift in resource allocation to the ear and indirectly improved reproductive resilience. Advances in root physiology and phenotyping can create opportunities to maintain long-term genetic gain in maize, but a shift from ideotype to crop and production system thinking will be required.
由于植物通过根系吸收水分和养分，因此有人提出，根系结构（RSA）的变化可能是过去一个世纪玉米（Zea mays L.）产量增加三倍的基础。在这里，我们表明，玉米育种几十年来，RSA 和产量都发生了变化，但作物的水分吸收量没有变化。在受控环境中进行的 X 射线表型分析结果表明，单交（SX）杂种的根系比双交（DX）杂种小，在 2465 µm 和 181 µm 之间的根直径（P<0.05）。在田间条件下测量的土壤水分提取量在 2.6 mm d-1 和 2.9 mm d-1 之间，但 SX 和 DX 杂种之间没有显著差异。在不同密度和灌溉条件下，SX 杂种的产量和产量构成均高于 DX 杂种（P<0.001）。总之，结果表明，RSA 的变化不是水分吸收增加的原因，而是现代农业高密度种植的一种适应。这种适应可能导致资源分配向穗部转移，间接提高了繁殖恢复力。根系生理学和表型的进步可以为玉米的长期遗传增益创造机会，但需要从理想型到作物和生产系统思维的转变。
