Is the NH4+-induced growth inhibition caused by the NH4+ form of the nitrogen source or by soil acidification?

Soil acidification often occurs when the concentration of ammonium (NH4+) in soil rises, such as that observed in farmland. Both soil acidification and excess NH4+ have serious adverse effects on crop growth and food production. However, we still do not know which of these two inhibitors has a greater impact on the growth of crops, and the degree of their inhibitory effect on crop growth have not been accurately evaluated. 31 wheat cultivars originating in various areas of China were planted under 5 mM sole NH4+ (ammonium nitrogen, AN) or nitrate nitrogen in combined with two pH levels resembling acidified conditions (5.0 and 6.5). The results showed that the shoots and roots biomass were severely reduced by AN in both and these reduction effects were strengthened by a low medium pH. The concentration of free NH4+ and amino acids, the glutamine synthetase activity were significantly higher, but the total soluble sugar content was reduced under NH4+ conditions, and the glutamine synthetase activity was reduced by a low medium pH. Cultivar variance was responsible for the largest proportion of the total variance in plant dry weight, leaf area, nodal root number, total root length and root volume; the nitrogen (N) form explains most of the variation in N and C metabolism; the effects of pH were the greatest for plant height and root average diameter. So, soil acidification and excess NH4+ would cause different degrees of inhibition effects on different plant tissues. The findings are expected to be useful for applying effective strategies for reducing NH4+ stress in the field

Response of Chinese cabbage (Brassica rapa subsp. pekinensis) to bacterial soft rot infection by change of soil microbial community in root zone

Chinese cabbage, scientifically known as Brassica rapa subsp. pekinensis, is a highly popular vegetable in China for its delectable taste. However, the occurrence of bacterial soft rot disease poses a significant threat to its growth and overall development. Consequently, this study aimed to explore the defense mechanisms employed by Chinese cabbage against bacterial soft rot disease. Specifically, the investigation focused on understanding the relationship between the disease and the microbial communities present in the soil surrounding the roots of Chinese cabbage. Significant disparities were observed in the composition of microbial communities present in the root-zone soil of healthy Chinese cabbage plants compared to those affected by Pectobacterium brasiliense-caused soft rot disease. The analysis of 16S rRNA gene high-throughput sequencing results revealed a lower abundance of Proteobacteria (8.39%), Acidobacteriot (0.85), Sphingomonas (3.51%), and Vicinamibacteraceae (1.48%), whereas Firmicutes (113.76%), Bacteroidota (8.71%), Chloroflexi (4.89%), Actinobacteriota (1.71%), A4b (15.52%), Vicinamibacterales (1.62%), and Gemmatimonadaceae (1.35%) were more prevalent in healthy plant soils. Similarly, the analysis of ITS gene high-throughput sequencing results indicated a reduced occurrence of Chytridiomycota (23.58%), Basidiomycota (21.80%), Plectosphaerella (86.22%), and Agaricomycetes (22.57%) in healthy soils. In comparison, Mortierellomycota (50.72%), Ascomycota (31.22%), Podospora (485.08%), and Mortierella (51.59%) were more abundant in healthy plant soils. In addition, a total of 15 bacterial strains were isolated from the root-zone soil of diseased Chinese cabbage plants. These isolated strains demonstrated the ability to fix nitrogen (with the exception of ZT20, ZT26, ZT41, ZT45, and ZT61), produce siderophores and indole acetic acid (IAA), and solubilize phosphate. Notably, ZT14 (Citrobacter freundii), ZT33 (Enterobacter cloacae), ZT41 (Myroides odoratimimus), ZT52 (Bacillus paramycoides), ZT58 (Klebsiella pasteurii), ZT45 (Klebsiella aerogenes), and ZT32 (Pseudomonas putida) exhibited significant growth-promoting effects as determined by the plant growth promotion (PGP) tests. Consequently, this investigation not only confirmed the presence of the soft rot pathogen in Chinese cabbage plants in Hangzhou, China, but also advanced our understanding of the defense mechanisms employed by Chinese cabbage to combat soft rot-induced stress. Additionally, it identified promising plant-growth-promoting microbes (PGPMs) that could be utilized in the future to enhance the Chinese cabbage industry

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Application Effect of Integrated Water and Fertilizer Technology for Tomato

Integrated water and fertilizer technology has the advantages of saving water, fertilizer and labour, which is widely applied in tomato plantation. Integrated water and fertilizer technology in topdressing and whole process of big and small tomatoes were studied, and their application effects were contrasted and analyzed, and application advantages and scopes of the two models were concluded

Fertilization Status and Soil Nutrient Condition in Some Asparagus Production Regions of Zhejiang Province

Asparagus is delicious, with rich nutrition, and it is one of main economic crops in Zhejiang Province. In this paper, by investigating fertilization situations of farmers in several asparagus production regions (Fuyang, Pinghu, Changxing and Cixi) and soil nutrient condition of asparagus garden with different plantation years, fertilization status and nutrient condition of asparagus garden were described, and fertilization suggestion was proposed, which aimed to guide scientific fertilization of asparagus and promote healthy development of industry

Enhanced selective CO2 adsorption on polyamine/MIL-101(Cr) composites

The global climate change induced by greenhouse gases has stimulated active research for developing efficient strategies to mitigate CO2 emission. In the present study, we prepared a series of polyamine/ metal-organic framework (MOF) composites as highly selective CO2 adsorbents from a CO2/N-2 mixture, which is relevant to CO2 capture in flue gas. We show that loading polyethyleneimine (PEI) into MIL101( Cr) frameworks can significantly enhance the selective CO2 adsorption capacity at low pressure and ambient temperature. Further, the comparative study reveals that both the particle size of the MOF and the molecular-weight of PEI play an important role in the CO2 capture ability. Regarding the particle size, smaller MIL-101(Cr) particles can facilitate the loading of PEI into the inner pores and result in lower surface area/pore volume. Thus, the resulting PEI/MIL-101(Cr) composites possess lower CO2 adsorption capacity, but are compensated by higher selectivity of CO2 over N-2. On the other hand, lower molecular-weight linear PEI could readily diffuse into the inner pores and effectively block the N-2 adsorption. As a result, the as-prepared A-PEI-300 sample in this work exhibits an excellent CO2 uptake of 3.6 mmol g(-1) and ultrahigh CO2/N-2 selectivity at 0.15 bar and 25 degrees C. In contrast, the higher molecular-weight branched PEI is advantageous at elevated temperature, since the composites can retain high CO2 adsorption capacity owing to the large amount of primary amine groups. Overall, polyamine/MOF composites are shown to be good candidate adsorbents for CO2 capture from flue gas. To achieve the optimal CO2 capture ability, comprehensive optimization of the polyamine and MOF structures should be performed