Frerichs Christian, Daum Diemo, Pacholski Andreas Siegfried
Faculty of Agricultural Sciences and Landscape Architecture, Osnabrueck University of Applied Sciences, Osnabrueck, Germany.
EuroChem Agro, Mannheim, Germany.
Front Plant Sci. 2020 Feb 28;10:1696. doi: 10.3389/fpls.2019.01696. eCollection 2019.
Organic pot-based production of basil ( L.) often has lower biomass yield than conventional cultivation. Previous investigations indicate that this growth impairment is related to high ammonium (NH ) concentrations in the growing media released by the mineralization of organic nitrogen (N) fertilizers. However, as a result of this ammonification process substrate pH may also increase. Under neutral to alkaline conditions NH is converted to ammonia (NH), which is known to be phytotoxic even at low concentrations. Therefore, we investigated the impact of both ammonical N species on basil grown in a peat substrate. In total, three fertilization pot experiments were conducted in a greenhouse in order to compare the effect of different organic base dressings [250 and 750 mg N (L substrate) mainly supplied by a liquid amino acid fertilizer (AAF)] and two initial substrate pH levels (5.5 and 6.5). In two treatments, 5% (v/v) mature compost was mixed into the peat 1 day and 12-days before the substrate was used for sowing, respectively. The aim of this procedure was to stimulate nitrification in this way to reduce ammonical N concentration. Ammonia concentration in the aerial plant surrounding environment was measured by using NH detector tubes in combination with an open-top chamber method. The results showed that the growth of basil (number of plants, fresh matter yield, plant height) was significantly inhibited in the second and third week of cultivation by rising NH and NH exposure, as well as by a substrate pH ≥ 7.0. These adverse effects were reduced by lowering the organic base dressing rate and adjusting the initial substrate pH to 5.5. Furthermore, the addition of mature compost to peat in combination with a 12-day storage was proven to be effective for promoting nitrification in the organically fertilized substrate. As a result, plant growth was improved by both lower NH and NH exposure as well as a faster supply of nitrate (NO ) as an additional N source. Using this approach, it was possible to feed organically fertilized basil right from the seedling stage with a NO -N/NH -N-balanced and later on providing a predominant NO -N supply.
有机盆栽罗勒（Ocimum basilicum L.）的生物量产量通常低于传统栽培方式。先前的研究表明，这种生长抑制与有机氮肥矿化释放到生长介质中的高铵（NH₄⁺）浓度有关。然而，由于这种氨化过程，基质pH值也可能升高。在中性至碱性条件下，NH₄⁺会转化为氨（NH₃），即使在低浓度下，氨也已知具有植物毒性。因此，我们研究了这两种含氨氮形态对在泥炭基质中生长的罗勒的影响。总共在温室中进行了三个施肥盆栽实验，以比较不同有机基肥[250和750 mg N/（L基质），主要由液体氨基酸肥料（AAF）提供]和两个初始基质pH水平（5.5和6.5）的效果。在两种处理中，分别在基质用于播种前1天和12天，将5%（v/v）的成熟堆肥混入泥炭中。此操作的目的是以这种方式刺激硝化作用，以降低含氨氮浓度。通过使用NH₃检测管结合开顶箱法测量空气植物周围环境中的氨浓度。结果表明，在栽培的第二周和第三周，罗勒的生长（植株数量、鲜重产量、株高）受到升高的NH₃和NH₄⁺暴露以及基质pH≥7.0的显著抑制。通过降低有机基肥施用量并将初始基质pH值调整为5.5，这些不利影响得以减轻。此外，将成熟堆肥添加到泥炭中并储存12天被证明对促进有机施肥基质中的硝化作用有效。结果，较低的NH₃和NH₄⁺暴露以及作为额外氮源的硝酸盐（NO₃⁻）更快供应都改善了植物生长。使用这种方法，从幼苗期就可以为有机施肥的罗勒提供NO₃⁻ - N/NH₄⁺ - N平衡的养分供应，随后提供主要的NO₃⁻ - N供应。
