High NH4+/NO3− Ratio Inhibits the Growth and Nitrogen Uptake of Chinese Kale at the Late Growth Stage by Ammonia Toxicity

Abstract

The aim of this study was to determine the effects of various NH4+/NO3− ratios in a nutrient solution on the growth and nitrogen uptake of Chinese kale under hydroponic conditions. The four NH4+/NO3− ratios in the nutrient solution were CK (0/100), T1 (10/90), T2 (25/75), and T3 (50/50). An appropriate NH4+/NO3− ratio (10/90, 25/75) promoted the growth of Chinese kale. T2 produced the highest fresh and dry weight among treatments, and all indices of seedling root growth were the highest under T2. A high NH4+/NO3− ratio (50/50) promoted the growth of Chinese kale seedlings at the early stage but inhibited growth at the late growth stage. At harvest, the nutrient solution showed acidity. The pH value was the lowest in T3, whereas NH4+ and NH4+/NO3− ratios were the highest, which caused ammonium toxicity. Total N accumulation and N use efficiency were the highest in T2, and total N accumulation was the lowest in T3. Principal component analysis showed that T2 considerably promoted growth and N absorption of Chinese kale, whereas T3 had a remarkable effect on the pH value. These findings suggest that an appropriate increase in NH4+ promotes the growth and nutrient uptake of Chinese kale by maintaining the pH value and NH4+/NO3− ratios of the nutrient solution, whereas excessive addition of NH4+ may induce rhizosphere acidification and ammonia toxicity, inhibiting plant growth.

An appropriate ammonium: nitrate ratio promotes the growth of centipedegrass: insight from physiological and micromorphological analyses

“…The appropriate NH 4 + :NO 3 - ratio promotes plant growth, and different species require different optimal NH 4 + :NO 3 - ratios. For example, the optimal NH 4 + :NO 3 - ratio is 0:100 for yellow flag ( Chang et al., 2010 ) and wheat ( Yang et al., 2021 ); 25:75 for Chinese cabbage cultivars ( Chen et al., 2005 ; Zhu et al., 2021 ), strawberry ( Tabatabaei et al., 2006 ), tomato ( Liu et al., 2017 ), Chinese kale ( Wang et al., 2021 ), and lettuce ( Du et al., 2022 ); 50:50 for cabbage ( Zhang et al., 2007 ), Sweet flag ( Chang et al., 2010 ), coffee ( Carr et al., 2020 ), soybean ( Raza et al., 2021 ), and blackberry ( Wei et al., 2023 ); 75:25 for pecan ( Chen et al., 2021 ); and 83:17 for blueberry ( Zhang et al., 2021 ). In this study, the effects of different NH 4 + :NO 3 - ratios on the growth parameters of centipedegrass were monitored and the NH 4 + :NO 3 - ratio of 50:50 treatment had the highest biomass and carbon and nitrogen accumulation ( Figure 3 ).…”

“…Notably, those studies mainly concentrate on Chinese cabbage ( Chen et al., 2005 ; Hu et al., 2017 ), strawberry ( Tabatabaei et al., 2006 ), cabbage ( Zhang et al., 2007 ), tomato ( Liu et al., 2017 ), maize ( Wang et al., 2019b ), coffee ( Carr et al., 2020 ), purple coneflower ( Ahmadi et al., 2021a ; Ahmadi et al., 2021b ; Ahmadi et al., 2022 ), pecan ( Chen et al., 2021 ), soybean ( Raza et al., 2021 ), Chinese kale ( Wang et al., 2021 ), wheat ( Yang et al., 2021 ), blueberry ( Zhang et al., 2021 ), flowering Chinese cabbage ( Zhu et al., 2021 ), lettuce ( Du et al., 2022 ), and blackberry ( Wei et al., 2023 ), with little attention given to grass plants. The growth promotion triggered by an appropriate NH 4 + :NO 3 - ratio is attributed to the accumulation of more carbon and nitrogen ( Chen et al., 2005 ), a higher leaf area and photosynthetic rate ( Tabatabaei et al., 2006 ; Hu et al., 2017 ; Liu et al., 2017 ; Wang et al., 2019b ; Carr et al., 2020 ; Raza et al., 2021 ; Zhang et al., 2021 ), a higher chlorophyll concentration ( Liu et al., 2017 ; Raza et al., 2021 ), increased auxin synthesis ( Wang et al., 2019b ), improved absorption of H 2 PO 4 – , K + , Ca 2+ , and Mg 2+ nutrients and a suitable proportion of nitrogen assimilation and storage ( Zhang et al., 2007 ; Carr et al., 2020 ), improved root growth and root/shoot ratio ( Ahmadi et al., 2021b ; Raza et al., 2021 ; Zhang et al., 2021 ), or maintenance of the pH value and NH 4 + :NO 3 - ratios of the nutrient solution ( Wang et al., 2021 ; Zhu et al., 2021 ). However, information regarding the role of plant micromorphological structure in growth promotion and the early-stage response of the above physiological parameters to the changes of different NH 4 + :NO 3 - ratios is still lacking.…”

Integration of algae treatment with hydroponic crop waste to reduce impact of nutrient waste streams

“…Where data exists regarding CEA systems, it is usually highly bespoke to the system design and conditions of the experiment, thus direct comparisons are difficult to make. Studies carried out on salad crops in CEA systems have shown a wide range of N‐NUEs, covering two orders of magnitude (2%–104%) (e.g., Consentino et al, 2022; Djidonou & Leskovar, 2019; Pennisi et al, 2019; Santamaria et al, 2002; Yang & Kim, 2020; Wang et al, 2021) (Table 4). Data are more difficult to find for other elements to make comparisons, which are poorly represented in literature.…”

The Effectiveness of Rice Husk Ash as Additive in Palm Oil-Based Compost in Enhancing the Nitrogen Uptake by Brassica oleracea var. alboglabra L. (Chinese Kale) Plant

“…Other than that, there is a need to conduct a field test study to refine the existing data obtained by previous researchers such as Di Mola et al (2020), Xiang et al (2019), and Y. Wang et al (2022), who also studied about the nitrogen uptake by leafy vegetables like Chinese kale plant. Therefore, this study attempted to investigate the effect of RHA addition to palm oil-based compost in enhancing the nitrogen uptake by the Chinese kale plant.…”