High starter phosphorus fertilization facilitates soil phosphorus turnover by promoting microbial functional interaction in an arable soil

Microbial phosphorus(P)turnover is critical in C utilization efficiency in agroecosystems.It is therefore necessary to understand the P mobilization processes occurring during P fertilization in order to ensure both crop yield and environmental quality.Here,we established a controlled pot experiment containing soil amended with three different levels of starter P fertilizer and collected soil samples after 30,60,and 90 days of incubation.Quantitative microbial element cycling(QMEC)smart chip technology and 16S rRNA gene sequencing were used to investigate functional gene structures involved in carbon,nitrogen and P cycling and the bacterial community composition of the collected samples.Although P fertilization did not significantly affect the structure of the soil microbial community,some rare microbiota were changed in particular phosphorus-solubilizing bacteria were enriched at the high P fertilization level,suggesting that the rare taxa make an important contribution to P turnover.P fertilization also altered the functional gene structure,and high P concentrations enhanced the functional gene diversity and abundance.Partial redundancy analysis further revealed that changes in rare taxa and functional genes of soil microorganisms drive the alteration of soil P pools.These findings extend our understanding of the microbial mechanisms of P turnover.

Effect of nitrogen limitation on antioxidant qualities is highly associated with genotypes of lettuce(Lactuca sativa L.)

Antioxidants are highly beneficial to human health, and their accumulation in lettuce, one of the most popular leafy vegetables, depends on both genetic and environmental factors. Nitrogen(N) availability plays an essential role in regulating antioxidant accumulation, but the influence of genotype × N interactions on the antioxidant qualities of lettuce is poorly understood. Therefore, the present study investigated the variation of growth and antioxidant qualities of 20 lettuce(Lactuca sativa L.) genotypes(10 green lettuce genotypes and 10 red lettuce genotypes) under limited N(low N, LN) conditions and standard N(high N, HN) conditions. For all 20 genotypes, LN conditions reduced shoot(i.e., leaf) growth, but increased plant concentrations of vitamin C,glutathione, and phenolic compounds, with the exception of carotenoids, compared with HN conditions. Because of reduced biomass under LN conditions, not all lettuce genotypes exhibited increased antioxidant yields or total antioxidant capacity yield. The variation in antioxidant quality was primarily genetically determined. Generally, the green lettuce genotypes exhibited more pronounced increases in antioxidant yields and total antioxidant capacity yield than the red lettuce genotypes under LN conditions. These results suggest that even though LN conditions generally tend to improve the antioxidant qualities of lettuce, the extent of this effect is highly dependent on genotype. Therefore, genotype should be given priority in future studies that aim to improve antioxidant qualities in lettuce through N management.