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Field experiments of sweet corn were carried out in Boluo county and Huiyang county of Guangdong province simultaneously in 2017 to determine the effects of one-off application of controlled-release urea combined with common urea on the biomass accumulation and nitrogen accumulation of spring sweet corn. Four treatments were employed in the experiments, including no nitrogen application treatment(CK), conventional nitrogen application treatment(U100, three times application) and 2 controlled-release urea combined with common urea under one-off application treatments (CCU100 and CCU80, which denoted 0% and 20% reduction of N rate based on U100, respectively). The blending ratio of controlled-release urea and common urea in CCU100 and CCU80 was 7:3. The results showed that nitrogen release characteristics of controlled-release urea in soil under spring sowing sweet corn were similar to the "S" line, and more than 85% of nitrogen from controlled-release urea had been released. The cumulative release rate of nitrogen from controlled-release urea was correlated with accumulated temperature positively. Comparing with U100, the biomass of sweet corn in CCU100 were increased by 4.68% (Boluo) and 6.75% (Huiyang) averagely, the nitrogen uptake of sweet corn in CCU100 were increased by 2.74% (Boluo) and 6.20% (Huiyang) averagely. No significant differences in accumulative of biomass of sweet corn between CCU80 and U100 treatments were observed. During harvest, the N uptake of sweet corn at Boluo in CCU80 treatment was 10.02% lower than that of U100 treatment (P<0.05). Compared with U100 treatment, the yield of CCU100 and CCU80 treatment did not decrease significantly. Compared with U100 treatment, the agronomic N use efficiencies and N recovery efficiency were significantly increased in CCU80 treatment(P<0.05), with an increase of 14.20% (Boluo) and 10.16% (Huiyang), and 4.92% (Boluo) and 22.03% (Huiyang) respectively. During harvest, N contents of straw and ear were increased significantly due to nitrogen application, but no significant differences in the nitrogen, phosphorus and potassium contents of straw and ear were observed among different N fertilization treatments. To sum up, for the production of spring sowing sweet corn in Guangdong province, one-off application of controlled-release urea combined with conventional urea could increase the nitrogen use efficiency while maintained crop yield, so it's an effective way to save labor and increase profit. [ABSTRACT FROM AUTHOR]

The CRF01_AE and CRF07_BC clades dominate the human immunodeficiency virus (HIV) epidemics in China. Both clades have been identified in the men who have sex with men (MSM) population in Guangdong province, raising a serious concern of possible complex recombination events ahead. Here, we report the first case of CRF01_AE/CRF07_BC recombinant sampled from a MSM patient in southern China. The genomic structure of this case is a mosaic with some regions resembling the CRF01_AE and CRF07_BC clades. Our phylogenetic analyses show that the two parental lineages of this recombinant virus were mainly found in the MSM population. This case has a different genomic composition compared with other recombinants descended from the same parental clades CRF01_AE and CRF07_BC. Our finding suggests that the MSM populations have become a hotspot for expanding viral diversity through the viral recombination mechanism. Therefore, further epidemiologic surveillance and monitoring should be conducted within the MSM populations to help advance our knowledge of viral transmission mechanisms. Additionally, these measures will serve to enhance the control and prevention of HIV/acquired immunodeficiency syndrome in China. [ABSTRACT FROM AUTHOR]

Guangdong Province is one of the most developed and populous provinces in southern China. The subtype situation of hepatitis C virus (HCV) in Guangdong remains unknown. The aim of this study was to investigate and estimate the HCV subtypes in drug users (DU) using a city-based sampling strategy to better understand the characteristics of HCV transmission in Guangdong. Archived plasma samples (n = 1074) from DU who were anti-HCV positive in 2014 were selected randomly from 20 cities in Guangdong Province. Subtypes were determined based on core and/or E1 sequences using phylogenetic analysis. The distributions of HCV subtypes in DU and different regions were analyzed. A total of 8 genotypes were identified. The three main HCV subtypes in DU in Guangdong were 6a (63.0%), 3a (15.2%), and 3b (11.8%). Significant differences were discovered among different registered residency and regions but not among genders, marital status, education level, or drug use patterns. HCV subtype 3b was significantly higher in Guangdong residents than in non-Guangdong residents. In contrast, HCV subtype 6a was significantly lower in Guangdong residents than in non-Guangdong residents. Subtype 1b in eastern Guangdong (eastern) was significantly lower, while 6a was significantly higher when compared with other regions. Subtype 3a in the Pearl River Delta (PRD) region was significantly higher, while 3b was significantly lower when compared with other regions. In western Guangdong, HCV subtype 3a was significantly lower when compared with other regions. Additionally, in northern Guangdong subtypes 1b and 3b were significantly higher, while 6a was significantly lower when compared with other regions. Our study revealed the diversity and distribution of HCV subtypes in DU in nearly all the cities in Guangdong. The results provide essential information that will allow the establishment of specific intervention strategies that may help prevent HCV transmission. • Eight HCV subtypes were detected among drug users in Guangdong, China. • HCV subtype 6a has spread quickly across the whole province. • The eastern cities may be the epidemic source of 6a in Guangdong. • The north of Guangdong has a special status in transmission of HCV. [ABSTRACT FROM AUTHOR]

Farmers are increasingly planting vegetables during the winter fallow period in the double-rice growing area of Guangdong Province, southern China. The intensified winter crop rotation system (rice-rice-vegetable, RRV) may improve the annual planting benefit and change the soil fertility. To address this, yields, biomass, and profitability of each crop in the RRV, relative to the traditional rice-rice-fallow system (RRF), were compared, and the dynamics of physical, chemical and biological properties of soil at different crop stages were determined in this paper. The annual crop yield, biomass and economic return of RRV were significantly higher than those of RRF due to the inclusion of winter vegetables (green beans) in the cropping system. The contribution of green beans to the total revenue per year for RRV was as high as 73%. Filling winter fallow with green beans had no influence on the yield of early and late rice. Soil NO 3 −-N, available P, exchangeable K, exchangeable Fe, exchangeable Cu and acid phosphatase activity at the winter stage were significantly higher in RRV than in RRF, whereas soil pH, soil organic carbon (SOC), dissolved organic carbon (DOC), exchangeable Ca, exchangeable Mg, catalase activity, dehydrogenase activity and invertase activity at the winter stage were lower. The soil NO 3 −-N, exchangeable Fe, exchangeable Cu, and acid phosphatase activity during the early rice stage also tended to be higher in the RRV system. The annual dynamics of soil physical, chemical and biological properties were proven to be greater in the RRV system than in the RRF system. The findings of our study contribute to the understanding of dynamic changes in physical, chemical and biological properties of soil across different crop stages due to intensified green bean planting during the winter fallow period in a double-rice cropping system, which will be useful for the sustainable development of RRV. • Yield and economic income increased significantly in RRV system than RRF system. • Most soil nutrients content were significantly higher in RRV than in RRF. • Soil pH, SOC, and some soil enzyme activity were lower in RRV than in RRF. • The annual dynamics of soil properties were proved to be greater in RRV than in RRF. [ABSTRACT FROM AUTHOR]

• BBU could harvest similar grain yield of rice with FP treatment. • N releasing rate of CRU was higher during late rice season than early rice season. • N release rate of S-CRU were slower and less sensitive to temperature than P-CRU. • S-BBU was more close to the N requirement of rice than P-BBU. Single basal application of bulk blending urea(BBU) which consists of both controlled-released urea(CRU) and conventional urea(U) has been proposed to facilitate fertilization and lower cost of CRU. Nevertheless, its effect on the growth, yield and N use efficiency(NUE) of rice in double rice cropping system under subtropical environment are still unknown. Field experiments were conducted at two different sites(Taishan county and Wengyuan county) simultaneously in Guangdong province to investigate the effects of single basal application of two types of BBU(P-BBU which consists of parabolic pattern CRU, and S-BBU which consists of sigmodial pattern CRU) on soil available N, grain yield and NUE. Conventional high-yield fertilization treatment with four split applications of U(FP) and no-N treatment(CK) were established as controls. The results demonstrated that BBU could provide similar or more adequate N nutrient for rice with FP during late rice season. BBU performed comparably to or better than FP on soil NH 4 +-N, dry matter, grain yield and NUE during late rice season. During early rice season, BBU performed comparably with FP on soil NH 4 +-N, N content of rice, dry matter, grain yield and NUE at Taishan site, while at Wengyuan site, it significantly reduced soil NH 4 +-N, N content of rice, dry matter and NUE compared with FP, and reduced grain yield slightly. Release tests in water and paddy field were conducted in order to evaluate the releasing dynamics of parabolic and sigmodial pattern CRU. Results showed that the N release rate of CRU in paddy field during early rice season was significantly slower than that during late rice season. This was closely correlated with the changing pattern of accumulated temperature. The N release rate of parabolic CRU in paddy field was faster and more sensitive to changing temperature than sigmodial CRU. Non-linear regression analysis shows that the N release patterns of sigmodial CRU in paddy fields were more close to N uptake of rice during both rice seasons. The grain yield of rice and NUE in S-BBU was higher slightly than P-BBU during both rice seasons. These results demonstrated that BBU obtained similar grain yield in double rice cropping system in South China, and S-BBU treatment is better for N requirement of rice during both seasons. Future studies should focus on optimizing and customizing the blending ratio of BBU for each rice season in double rice cropping system to increase crop yield and the robustness of BBU to changing weather conditions. [ABSTRACT FROM AUTHOR]