Li Cui, Wang Peng, Menzies Neal W, Lombi Enzo, Kopittke Peter M
The University of Queensland, School of Agriculture and Food Sciences, St Lucia, Queensland, 4072, Australia.
Nanjing Agricultural University, College of Resources and Environmental Sciences, Nanjing, 210095, China.
Ann Bot. 2017 Sep 1;120(3):405-415. doi: 10.1093/aob/mcx063.
Foliar fertilization to overcome nutritional deficiencies is becoming increasingly widespread. However, the processes of foliar nutrient absorption and translocation are poorly understood. The present study aimed to investigate how cuticular leaf properties affect the absorption of foliar-applied nutrients in leaf tissues.
Given that methyl jasmonate (MeJA) can cause alterations in leaf properties, we applied 1 mm MeJA to sunflower (Helianthus annuus), tomato (Solanum lycopersicum) and soybean (Glycine max) to assess changes in leaf properties. Using traditionally analytical approaches and synchrotron-based X-ray fluorescence microscopy, the effects of these changes on the absorption and translocation of foliar-applied Zn, Mn and Fe were examined.
The changes in leaf properties caused by the application of MeJA increased foliar absorption of Zn, Mn and Fe up to 3- to 5-fold in sunflower but decreased it by 0·5- to 0·9-fold in tomato, with no effect in soybean. These changes in the foliar absorption of nutrients could not be explained by changes in overall trichome density, which increased in both sunflower (86%) and tomato (76%) (with no change in soybean). Similarly, the changes could be not attributed to changes in stomatal density or cuticle composition, given that these properties remained constant. Rather, the changes in the foliar absorption of Zn, Mn and Fe were related to the thickness of the cuticle and epidermal cell wall. Finally, the subsequent translocation of the absorbed nutrients within the leaf tissues was limited (<1·3mm) irrespective of treatment.
The present study highlights the potential importance of the combined thickness of the cuticle and epidermal cell wall in the absorption of foliar-applied nutrients. This information will assist in increasing the efficacy of foliar fertilization.
通过叶面施肥来克服营养缺乏的做法正变得越来越普遍。然而，叶面养分吸收和转运的过程却鲜为人知。本研究旨在探究叶片角质层特性如何影响叶片组织对叶面施用养分的吸收。
鉴于茉莉酸甲酯（MeJA）可引起叶片特性的改变，我们对向日葵（Helianthus annuus）、番茄（Solanum lycopersicum）和大豆（Glycine max）施用1 mM的MeJA，以评估叶片特性的变化。使用传统分析方法和基于同步加速器的X射线荧光显微镜，研究了这些变化对叶面施用的锌、锰和铁的吸收及转运的影响。
施用MeJA引起的叶片特性变化使向日葵对锌、锰和铁的叶面吸收增加了3至5倍，但使番茄的吸收减少了0.5至0.9倍，对大豆则无影响。叶面养分吸收的这些变化无法用总体毛状体密度的变化来解释，总体毛状体密度在向日葵（增加86%）和番茄（增加76%）中均增加（大豆无变化）。同样，这些变化也不能归因于气孔密度或角质层组成的变化，因为这些特性保持不变。相反，锌、锰和铁的叶面吸收变化与角质层和表皮细胞壁的厚度有关。最后，无论处理如何，吸收的养分在叶片组织内的后续转运都很有限（<1.3mm）。
本研究强调了角质层和表皮细胞壁的综合厚度在叶面施用养分吸收中的潜在重要性。这些信息将有助于提高叶面施肥的效果。
