Improving grain yield and nitrogen use efficiency of direct-seeded rice with simplified and nitrogen-reduced practices under a double-cropping system in South China.

BACKGROUND: Enhancing grain yield and nitrogen use efficiency (NUE) of rice is of great importance for sustainable agricultural development. Little effort has been made to increase grain yield and NUE of direct-seeded rice under the double-cropping system in South China. Field trials were conducted during 2018-2020 with four treatments, including nitrogen-free, farmers' fertilization practice (FP), 'three controls' nutrient management (TC), and simplified and nitrogen-reduced practice (SNRP). RESULTS: Grain yield under SNRP averaged 6.46 t ha-1 during the three years and was 23.0% higher than that of FP but comparable to that of TC. Recovery efficiency (REN ), agronomic efficiency (AEN ), and partial factor productivity (PFPN ) of nitrogen under SNRP increased by 12.0-22.7%, 159.3-295.0% and 94.6-112.5% respectively compared with FP. Harvest index and sink capacity increased by 7.3-10.8% and 14.9-21.3% respectively. Percentage of productive tillers (PPT) and biomass after heading increased by 24.0% and 104.5% respectively. Leaf nitrogen concentration at heading and nitrogen accumulation after heading increased by 16.3% and 842.0% respectively. Grain yield was positively correlated with PPT, sink capacity, harvest index, biomass and nitrogen accumulation after heading, REN , AEN , and PFPN . CONCLUSION: Grain yield and NUE under SNRP were superior to those under FP and comparable to those under TC. Increase in sink capacity, higher PPT, more biomass and nitrogen accumulation after heading, and greater harvest index were responsible for high grain yield and NUE in SNRP with reduced nitrogen fertilizer and labor input. SNRP is a feasible approach for direct-seeded rice under a double-cropping system in South China. © 2023 Society of Chemical Industry.

[High-frequency ultrasonography for diagnosis and differential diagnosis of acute scrotum in children].

OBJECTIVE: To analyze the high-frequency ultrasound image features of acute scrotum in children and explore the value of high-frequency ultrasonography in the diagnosis and differential diagnosis of the disease. METHODS: This retrospective study included 256 children aged 2 days to 14 years undergoing color Doppler ultrasonography at 2 hours to 3 days after onset of acute scrotum. We analyzed the morphology, internal echo and blood supply of the testis in comparison with the clinical and pathological results. RESULTS: Among the 256 cases, acute testicular torsion was found in 23, of which 16 were treated by complete resection the necrotic testis and the other 7 by surgical reduction of testicular torsion. Ultrasonographically, the involved testes presented different degrees of increase or decrease in volume, with uneven internal echoes, irregular hypoechoic flakes, and testicular hydrocele. Color Doppler flow imaging (CDFI) showed significant blood flow signals around the diseased testes but none within them. Acute testicular appendix torsion was found in 116 cases, in which ultrasonography manifested nodules with round or oval abnormal echoes between the upper pole of the testis and caput epididymidis, first hypoechoic and then gradually increased, heterogeneous internally. CDFI revealed enlarged epididymides and enriched testicular blood flow but no blood flow signals in the nodules. The 103 cases of acute epididymitis were ultrasonographically characterized by varied degrees of swelling of the involved epididymis with uneven internal echoes and rich blood flow signals on CDFI. Six of the cases were diagnosed as acute orchitis, with the ultrasonographic features of testicular swelling and low but uniform internal echoes, with rich blood flow signals on CDFI. Incarcerated inguinal hernia was confirmed in 15 cases, in which ultrasonography revealed intrusion of the hernia into the obviously enlarged scrotal sac with the mesentery and intestine in it, and blood flow visible on CDFI. Acute scrotal wall hematoma and edema was found in 8 cases, with the ultrasonographic characteristics of scrotal wall thickening, with visible blood flow signals on CDFI. CONCLUSIONS: High-frequency ultrasonography has a high sensitivity and specificity for acute scrotum in children, which can be applied as the first-choice clinical imaging modality and provide reliable evidence for the diagnosis and differential diagnosis of the disease.

The immunological adjuvant activity of gypenosides liposome against Newcastle disease vaccine.

The adjuvant activity of gypenosides liposome (GPSL) encapsulated with liposome was investigated in vitro and in vivo. In vitro, different concentrations of GPSL were added into chicken's peripheral blood lymphocytes and splenic lymphocyte. The results showed that GPSL could significantly enhance T and B lymphocytes proliferation singly or synergistically with PHA and LPS and the efficacy were superior to those of gypenosides (GPS) and blank liposome (BL) at most of concentrations. In vivo, three hundred and fifty 14-day-old chickens were assigned to 7 groups randomly and vaccinated with Newcastle disease (ND) vaccine. Simultaneously, the chickens in experimental groups were, respectively, oral administration with the GPSL at three doses, GPS and BL. The results showed that GPSL could significantly enhance lymphocyte proliferation, increase antibody titer, and promote cytokine secretion in vitro and in vivo, moreover, the adjuvant activity of GPSL was better than those of GPS and BL. These indicated that formulations of GPS and liposome can further enhance the immune response against ND vaccine compared with the adjuvant alone.

Immunoenhancement effect of rehmannia glutinosa polysaccharide on lymphocyte proliferation and dendritic cell.

The aim of this study is to investigate immunomodulatory effect of rehmannia glutinosa polysaccharide (RGP) on murine splenic lymphocyte and bone marrow derived dendritic cells (DCs). Splenic lymphocytes obtained from mice were co-cultured with RGP for 48 h and then harvested for analyzing with MTT method. The cytokine production of T lymphocytes was measured by ELISA. Effects of RGP treatment on DCs were investigated and assessed by MTT method. The results showed RGP significantly stimulated lymphocyte proliferation and the growth rate of T cell was more significant. The IL-2 and IFN-γ production of T lymphocyte were significantly upregulated after being stimulated with RGP. DCs stimulating on proliferation of T cells and the ability of antigen presenting of DCs have been enhanced under the stimulation of RGP. In conclusion, these findings provided valuable information that RGP possessed strong immunoenhancement activity, which provided the theoretical basis for the further experiment.