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In order to solve the problems of nitrogen (N) losses and fruit quality degradation caused by excessive N fertilizer application, different dosages of the nitrification inhibitor, 3,4dimethylpyrazole phosphate (DMPP) (0, 0.5, 1, 2, and 4 mg kg −1 soil), were applied during the later stage of 'Red Fuji' apple (Malus domestica Borkh.) fruit expansion in 2017 and 2018. The effects of DMPP on soil N transformation, carbon (C)-N nutrition of tree, and fruit quality were investigated. Results revealed that DMPP decreased the abundance of ammonia-oxidizing bacteria (AOB) amoA gene, increased the retention of NH 4 +-N, and decreased NO 3 −-N concentration and its vertical migration in soil. DMPP reduced 15 N loss rates and increased 15 N residual and recovery rates compared to the control. 13 C and 15 N double isotope labeling results revealed that DMPP reduced the capacity of 15 N absorption and regulation in fruits, decreased 15 N accumulation in fruits and whole plant, and increased the distribution of 13 C from vegetative organs to fruits. DMPP increased fruit anthocyanin and soluble sugar contents, and had no significant effect on fruit yield. The comprehensive analysis revealed that the application of 1 mg DMPP kg −1 soil during the later stage of fruit expansion effectively reduced losses due to N and alleviated quality degradation caused by excessive N fertilizer application.

Root-lesion nematodes are major pathogens of wheat and have been reported in the United States, Mexico, India, Australia, Egypt, Canary Islands, South Africa, Iran, Japan, the Netherlands, Belgium, Italy, Germany, and Yugoslavia (1). They can also cause injury in a large number of crops, including grasses, cereal grains, and vegetables. In 2009 and 2010, a survey was conducted for nematodes in winter wheat fields near Taian city, Shandong, northern China. Root tissues were stained via the acid fuchsin tissue stain technique, and nematode numbers were recorded under a stereo microscope. Sixty-eight root samples were collected during the winter wheat growing season, and root lesion nematode was found in all samples. The highest average lesion nematode populations in fresh roots were 154.3 nematodes/g in 2009 and 236.7 nematodes/g in 2010. Nematodes were collected from infested wheat roots by a modified Baermann funnel method. Dimensions of the nematodes were: length, 0.42 to 0.54 mm; a, 18.8 to 24.2; b, 4.4 to 5.7; c, 19.8 to 25.4; V, 80.4 to 84.8; and spear, 17.1 to 18.9 μm. DNA was extracted from individual nematodes using liquid nitrogen. Amplification of rDNA-internal transcribed spacer region using the forward primers 5′-CGTAACAAGGTAGCTGTAG-3′ and the reverse primer 5′-TTTCACTCGCCGTTACTAAGG-3′ yielded a PCR fragment of approximately 900 bp. PCR products were purified using Universal Plant DNA Purification Kit (Tiangen, China) and ligated to the pMD18-T vector system (TaKaRa Bio, Japan) and transformed to E. coli strain DH5α. Plasmid DNA carrying the insert was extracted and used as the template for DNA sequencing. DNA sequencing was carried out in an ABI 3730, compared and aligned using MEGA 5.0. Sequences showed 96% sequence identity with those of Pratylenchus neglectus (GenBank Accession No. FR692291.1). The sequence was submitted to the GenBank database (JX228136). To our knowledge, this is the first report of P. neglectus infesting winter wheat in China. P. neglectus has been reported as causing economically significant damage to wheat production of up to 70% yield loss in the Pacific Northwest. Damage from lesion nematode may therefore be potentially significant to wheat production in Shandong Province, and further information should be obtained on its prevalence. References: (1) P. A. A. Loof. The family Pratylenchidae Thorne, 1949. W. R. Nickle, ed., Manual of Agricultural Nematol. Marcel Dekker, Inc. New York, 1991. (2) R. W. Smiley et al. J. Nematol. 37:45, 2005.

No abstract

Nutrient-depleted soil is a major constraint for crop production, particularly for fruits. Here, we investigated the different response of nitrogen (N), phosphorus (P), and potassium (K) deficiency on the growth and development of strawberry (Fragaria ×ananassa Duch.) in sand culture under greenhouse conditions. Compared with K, the lack of N or P is more unfavorable to strawberry growth and development. N deficiency affected shoot-root (S/R) ratio at different growth stages, and decreased the shoot biomass. P deficiency greatly increased the N content but decreased K content of the plants, which means P is of advantage to regulate the absorption and utilization of N and K nutrients in plants. Meanwhile, P has a profound influence on fruit quality, such as total soluble (TSS) sugar content. K deficiency is not conducive to fruit coloring and the formation of high-quality commercial fruits. The results contribute to a better understanding of the difference of N, P, or K deficiency on strawberry growth, nutrient absorption, and fruit quality during the whole growth period.

No abstract

In the old course of the Yellow River area, most orchards are over-applied with nitrogen (N) fertilizers. To improve N management in this area, a 15N tracing experiment was conducted to investigate the absorption, distribution and loss of spring-topdressing urea in pear orchards from March to August 2019. The 7-year-old Sucui 1 pear was used as the test material, and 277.5 g of ordinary urea and 15 g of 15N-urea N were evenly applied to each plant. The N absorption, distribution and utilization efficiency of different organs from the flowering stage to the post-harvest stage were analyzed, and the residual and loss of N in the soil were also discussed. The N fertilizer utilization rate increased with the advancement of the phenological period. The N fertilizer utilization rate in the full bloom period is 10.39%, which is the fastest growing period, and reached a maximum of 23.62% in the post-harvest stage. In the young fruit stage, the amount of N derived from labeled fertilizer (%Ndff) of the fruit was only 1.02%, and most of the new vegetative organs were above 1%. Residual amount in the 20–40 cm soil layer was significantly higher than that in other soil layers. Direction of N fertilizer is N fertilizer loss>soil residue>tree absorption. N loss in the fruit expansion stage and the harvest stage is higher, which are 3.76 g and 3.74 g, respectively. N utilization rate in this area is low throughout the year. There is nutrient competition between reproductive growth and vegetative growth, which can be effectively alleviated by spring top-dressing. The N loss during fruit expansion and harvesting is serious. Attention should be paid to split fertilizer application and the timely supplementation of an appropriate amount of N fertilizer to improve N use efficiency.

Phosphorus-solubilizing microorganisms play an important role in soil nutrient phosphorus cycling. In order to clarify the effect of glucose (C6H12O6) on soil phosphorus transformation, the effects of glucose additions on the bacterial community, soil phosphorus status, and plant phosphorus uptake in apple rhizosphere soil were investigated. A 90-day pot experiment was carried out, and the experiment was repeated three times. Glucose additions were 0, 2.5, 5, 7.5, 10, and 12.5 g glucose per kg of soil. We measured soil bacteria and phosphorus related indexes using Illumina MiSeq sequencing technology and chemical methods. The results showed that when the glucose application rate was 2.5–7.5 g·kg−1, the soil total phosphorus content decreased by 4.4–7.3%; however, the soil acid phosphatase activity increased by 0.5–1.3 times, and the microbial biomass phosphorus increased by 29.1% and 37.0%. The content of Al-P and Fe-P in the rhizosphere soil decreased by 14.4 to 32.7 mg·kg−1 and 16.04 to 28.7 mg·kg−1, respectively. The compositional difference of the bacterial community became larger, and the relative abundance of 11 bacterial phyla changed significantly, among which the most significant change was found in Proteobacteria. This study also found that the relative abundances of Bacillus, Pseudomonas, Arthrobacter, and Cuprococcus increased by 0.9%, 2.2%, 2.4%, and 0.8%, respectively. Applying 7.5 g glucose per kg of soil can significantly increase the relative abundance of phosphorus solubilizing bacteria (Bacillus, Pseudomonas, Arthrobacter et al.) in rhizosphere soil, activate Al-P and Fe-P, and improve the availability of soil phosphorus.