Effects of nitrogen application on phytochemical component levels and anticancer and antioxidant activities of Allium fistulosum.

BACKGROUND: Allium fistulosum L. has good nutritional value and is cultivated worldwide as an efficacious traditional medicinal plant. Its biological activities are attributable to its phytochemicals. Nitrogen is an essential nutrient for plant growth and development; however, the effect of nitrogen levels on the level of active components in this species is not well understood. METHODS: In this study, using urea fertilizer, we investigated the effects of different nitrogen levels (N0, N1, and N2 at 0, 130, and 260 kg/ha, respectively) on the phytochemical constituents , and antioxidant and anticancer properties of A. fistulosum. RESULTS: The results suggested that nitrogen fertilizers have a significant effect on the level of total phenols and flavonoids. The analysis of the antioxidant capacity revealed that the lowest IC50 values corresponded to plants treated with the highest nitrogen concentration. Anticancer activity was investigated against cancer cell lines (HeLa and HepG2), and the extracts of A. fistulosum treated with a high nitrogen level showed the highest antiproliferative effect. Collectively, our results suggest that nitrogen fertilizer application enhanced the quality of A. fistulosum, particularly its health benefits.

Correction: High nitrogen concentration alter microbial community in Allium fistulosum rhizosphere.

[This corrects the article DOI: 10.1371/journal.pone.0241371.].

High nitrogen concentration alter microbial community in Allium fistulosum rhizosphere.

Welsh onion (Allium fistulosum L.) constitutes an important plant species cultivated in China due the benefits and applications in different areas. Moreover, nitrogen is an essential nutrient during the growth and development of plant. Here, we present the effects of nitrogen on soil microbiome in welsh onion plants. We used High-throughput sequencing analysis to determine the diversity and abundances of microbes associated to soil rhizosphere in welsh onion under the influence of nitrogen application. Nitrogen application significantly influenced in the diversity of fungal community. The relative abundance of Orbiliomycetes increased with the nitrogen concentration. Nitrogen application did not affect the diversity of bacterial community, whereas the relative abundance of Acidobacteria_Gp2, Verrucomicrobiae and Sphingobacteriia decreased with the nitrogen condition. In this work, we introduced evidences of the effect of nitrogen fertilization on microbial community in welsh onion rhizosphere, and the change of microbial community may interfere the growth and development of welsh onion.

Estimating nutrient uptake requirements for radish in China based on QUEFTS model.

Imbalanced fertilization has caused lower yield and nutrient use efficiency for radish (Raphanus sativus L.) production in China. Estimating nutrient requirements for radish is crucial in optimizing fertilization to resolve the problem. On-farm experiments in the radish-growing regions of China from 2000 to 2017 were collected to investigate the relationship between fleshy root yield and nutrient accumulation in radish plant using the Quantitative Evaluation of the Fertility of Tropical Soils (QUEFTS) model. The QUEFTS model predicted a linear increase in fleshy root yield if nutrients were taken up in balanced amounts until yield reached about 60%-70% of the potential yield. The balanced N, P, and K requirements in radish plant simulated by the QUEFTS model were 2.15, 0.45, and 2.58 kg to produce 1000 kg of fleshy root, and the corresponding internal efficiencies (IEs, kg fleshy root per kg nutrient in total plant dry matter) for N, P, and K were 465.1, 2222.2, and 387.1 kg kg-1. The simulated balanced N, P, and K removal by fleshy root to produce 1000 kg fleshy root were 1.34, 0.30, and 1.93 kg, respectively. Approximately 62%, 67%, and 75% of N, P, and K in radish plant were presented in the fleshy root and removed from the soil. Field validation experiments confirmed the consistency between the observed and simulated nutrient uptake values. The QUEFTS model was proven to be effective for estimating nutrient requirements of radish and will contribute to develop fertilizer recommendations for radish cultivated in China.

Humic Acid Fertilizer Improved Soil Properties and Soil Microbial Diversity of Continuous Cropping Peanut: A Three-Year Experiment.

Although humic acid has been demonstrated to improve the quality of some soil types, the long-term effects of humic acid on soil under continuous cropping peanut are not fully understood. This study aimed to investigate the continuous effects of humic acid on the physicochemical properties, microbial diversity, and enzyme activities of soil under continuous cropping peanut. In this study, a three-year consecutive experiment of cropping peanut was conducted in the North China Plain. In addition to the equal nitrogen, phosphorus, and potassium inputs, humic acid treatment was applied with inorganic fertilizers. Compared with control experiments, humic acid increased the yield and quality of continuous cropping peanut. To elucidate the mechanism of humic acid affecting the soil quality, various soil quality indicators were evaluated and compared in this study. It was found that humic acid increased soil nutrient contents, including the total soil nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus, available potassium, and organic matter contents, which exhibited the maximum effect in the third year. Meanwhile, the urease, sucrase, and phosphatase activities in the soil significantly increased after treated with humic acid, of which the maturity period increased most significantly. The same results were observed for three consecutive years. Microbial diversity varied considerably according to the high throughput sequencing analysis. Specifically, the number of bacteria decreased while that of fungi increased after humic acid treatment. The abundance of Firmicutes in bacteria, Basidiomycota, and Mortierellomycota in fungi all increased, which have been reported as being beneficial to plant growth. In contrast, the abundance of Ascomycota in fungi was reduced, and most of the related genera identified are pathogenic to plants. In conclusion, humic acid improved the yield and quality of continuous cropping peanut because of improved physicochemical properties, enzymatic activities, and microbial diversity of soil, which is beneficial for alleviating the obstacles of continuous cropping peanut.