Arsic Maja, Howell Nicholas R, Cresswell Tom, Brunetti Gianluca, Husted Søren, Schjoerring Jan Kofod, Persson Daniel P, Lombi Enzo, Doolette Casey L
University of South Australia, Future Industries Institute, Mawson Lakes, South Australia, Australia.
Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Physiol Plant. 2025 May-Jun;177(3):e70263. doi: 10.1111/ppl.70263.
Plant nutrient deficiencies can modify leaf surface properties and may affect the absorption of foliar fertilisers. This study examined how plant P-deficiency modified the adaxial leaf surface morphology of four barley cultivars and whether these modifications could be linked to quantitative differences in foliar-applied P absorption. Four Australian barley cultivars were grown hydroponically under P-sufficient and P-deficient conditions. A P radiolabelled foliar phosphate solution was applied to adaxial leaf surfaces for 2 or 7 days to investigate absorption and translocation. All cultivars showed different responses to P-deficiency (stomatal density, trichome density, thickness of the epidermal cell wall and cuticle). However, no clear trends were observed among the cultivars in their responses to P deficiency. Cultivars absorbed foliar-applied P regardless of plant P status. Remobilisation occurred from the treated leaf to untreated shoots in all but one cultivar. While P-deficient plants absorbed and accumulated significantly less foliar-applied P after 7 days, this was not linked to measured changes in stomatal or trichome density or the thickness of the epidermal cell wall and cuticle. Autoradiographs revealed that P accumulation was limited to newly emerging leaves in P-deficient plants, while P-sufficient plants also remobilized and accumulated P into older leaves and tillers. Relatively high P absorption (> 65% of foliar-applied P) in both P-sufficient and P-deficient plants suggests that foliar-applied P may be a useful fertiliser top-up strategy for barley. Due to the lower absorption in P-deficient barley, foliar applications should be made before severe P-deficiency symptoms are apparent to improve absorption.
植物养分缺乏会改变叶片表面特性，并可能影响叶面肥料的吸收。本研究调查了植物缺磷如何改变四个大麦品种叶片近轴面的形态，以及这些改变是否与叶面施磷吸收的定量差异有关。四个澳大利亚大麦品种在磷充足和缺磷条件下进行水培生长。将一种放射性磷标记的叶面磷酸盐溶液施用于叶片近轴面2天或7天，以研究吸收和转运情况。所有品种对缺磷均表现出不同的反应（气孔密度、毛状体密度、表皮细胞壁和角质层厚度）。然而，各品种对缺磷的反应未观察到明显趋势。无论植物的磷状况如何，各品种均能吸收叶面施用的磷。除一个品种外，所有品种均发生了从处理叶向未处理枝条的转运。虽然缺磷植株在7天后吸收和积累的叶面施磷显著减少，但这与气孔或毛状体密度以及表皮细胞壁和角质层厚度的测量变化无关。放射自显影片显示，缺磷植株中的磷积累仅限于新长出的叶片，而磷充足的植株还将磷转运并积累到老叶和分蘖中。磷充足和缺磷植株中相对较高的磷吸收（>叶面施磷的65%）表明，叶面施磷可能是大麦一种有用的追肥策略。由于缺磷大麦的吸收较低，应在明显出现严重缺磷症状之前进行叶面施肥，以提高吸收。
