Molecular Plant Nutrition, Leibniz-Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstr. 3, 06466, Gatersleben, Germany.
Crop Production and Crop Protection, Institute of Biomass Research, University of Applied Sciences Weihenstephan-Triesdorf, Markgrafenstrasse 16, 91746, Weidenbach, Germany.
Sci Rep. 2020 Nov 25;10(1):20504. doi: 10.1038/s41598-020-77467-3.
Cereal crop yield comprises interrelated components, among which the number of tillers is highly responsive to nitrogen fertilization. We addressed the hypothesis of whether the supply of different nitrogen forms can be employed to manipulate the tiller number in cereal crops. Relative to urea or ammonium, exclusive supply of nitrate increased tiller number in hydroponically-grown barley plants. Thereby, tiller number correlated positively with the root-to-shoot translocation rate of endogenous cytokinins. External supply of a synthetic cytokinin analog further stimulated tillering in nitrate-containing but not in urea-containing nutrient solution. When the cytokinin analog 6-benzylaminopurine riboside was externally supplied to roots, its translocation to shoots was 2.5 times higher in presence of nitrate than in presence of urea or ammonium, suggesting that cytokinin loading into the xylem is affected by different nitrogen forms. We then translated this finding to field scale, cultivated winter wheat in four environments, and confirmed that nitrate fertilization significantly increased tiller number in a dose-dependent manner. As assessed in 22 winter wheat cultivars, nitrogen form-dependent tiller formation was subject to substantial genotypic variation. We conclude that cytokinin-mediated signaling effects of fertilizer nitrogen forms can be employed as a management tool to regulate the tiller number in cereal crops.
谷类作物的产量由相互关联的组成部分构成，其中分蘖数对氮素施肥反应极为敏感。我们研究了这样一个假设，即不同氮素形态的供应是否可以用于操纵谷类作物的分蘖数。与尿素或铵盐相比，单独供应硝酸盐会增加水培大麦植物的分蘖数。因此，分蘖数与内源细胞分裂素从根到梢的转运率呈正相关。在含有硝酸盐而不是含有尿素的营养液中，外源提供合成细胞分裂素类似物进一步刺激分蘖。当将细胞分裂素类似物 6-苄氨基嘌呤核糖苷外施到根部时，其向地上部的转运在有硝酸盐存在时比在有尿素或铵盐存在时高 2.5 倍，这表明细胞分裂素进入木质部的装载受到不同氮形态的影响。然后，我们将这一发现转化到田间规模，在四个环境中种植冬小麦，并证实硝酸盐施肥以剂量依赖的方式显著增加分蘖数。在 22 个冬小麦品种中，氮素形态依赖性分蘖形成存在显著的基因型差异。我们得出结论，细胞分裂素介导的肥料氮素形态信号效应可以作为一种管理工具，用于调节谷类作物的分蘖数。
