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Effects of water and fertilizer deficit regulation with drip irrigation at different growth stages on fruit quality improvement of kiwifruit in seasonal arid areas of Southwest China
ZHA Yu-xuan, CHEN Fei, WANG Zhi-hui, JIANG Shou-zheng, CUI Ning-bo
2023, 22 (10): 3042-3058.   DOI: 10.1016/j.jia.2023.08.015
Abstract146)      PDF in ScienceDirect      

For a long time, seasonal drought occurs frequently in Southwest China, and the management of water and fertilizer in kiwifruit orchards has no quantitative standards, which seriously affects the yield and quality of kiwifruit.  Therefore, the effects of water and fertilizer deficit regulation with drip irrigation (WFDRDI) on the quality of kiwifruit at different growth stages were explored to achieve water and fertilizer saving, and green and efficient production of kiwifruit.  We select ‘Jin Yan’ kiwifruit and set two water deficit levels (WD20% and WD40%) and three fertilizer deficit levels (FD15%, FD30% and FD45%) at bud burst to leafing stage (stage I), flowering to fruit set stage (stage II), fruit expansion stage (stage III) and fruit maturation stage (stage IV), respectively, with a full irrigation and fertilization as the control treatment (CK) in 2017 and 2018.  Results showed that the WFDRDI at stage II and III had significant effect on fruit physical quality of kiwifruit, specifically, the III-WD40%FD30% and III-WD20%FD45% treatments significantly increased fruit firmness by 13.62 and 15.59% (P<0.05), respectively; the II-WD40%FD15% and III-WD40%FD15% treatments significantly increased dry matter by 8.19 and 6.47% (P<0.05), respectively; the III-WD20%FD15% treatment significantly increased single fruit weight and fruit volume by 9.33 and 12.65% (P<0.05), respectively; the II-WD20%FD15% treatment significantly increased fruit water content by 1.99% (P<0.05).  The WFDRDI had an obvious effect on fruit chemical quality of kiwifruit.  The III-WD20%FD45%, IV-WD40%FD15% and IV-WD20%FD30% treatments significantly increased vitamin C (Vc) content by 69.96, 36.96 and 34.31% (P<0.05), respectively; the III-WD40%FD15% and IV-WD40%FD15% treatments significantly increased total soluble solid (TSS) content by 3.79 and 17.05% (P<0.05), respectively, and significantly increased soluble sugar content by 28.61 and 34.79% (P<0.05), respectively; the contents of fructose, glucose and sucrose also had a significantly increasing trend, which was increased significantly by 5.58–19.63%, 40.55–60.36% and 54.03–54.92% in the III-WD40%FD15% and IV-WD40%FD15% treatments (P<0.05), respectively; sugar–acid ratio was increased significantly in the IV-WD40%FD15% treatment by 64.65% (P<0.05).  The degree and duration of water and fertilizer deficit had a comprehensive effect on fruit quality of kiwifruit.  The WFDRDI at stage II and III contribute to improving fruit physical quality, and the threshold of water and fertilizer deficit were 20 and 15%, respectively; stage III and IV are the critical periods for improving fruit chemical quality by water and fertilizer coupling effect, and the threshold of water and fertilizer deficit were 40 and 15%, respectively.  Therefore, aiming at precise water and fertilizer saving, the I-WD20%FD30%, II-WD40%FD15%, III-WD40%FD15% and IV-WD40%FD15% treatments under WFDRDI during the whole growth period of kiwifruit were the best mode to improve quality and production of kiwifruit.

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Glycosylation of the hemagglutinin protein of H9N2 subtype avian influenza virus influences its replication and virulence in mice
TAN Liu-gang, CHEN Zhao-kun, MA Xin-xin, HUANG Qing-hua, SUN Hai-ji, ZHANG Fan, YANG Shao-hua, XU Chuan-tian, CUI Ning
2019, 18 (7): 1443-1450.   DOI: 10.1016/S2095-3119(19)62669-9
Abstract209)      PDF in ScienceDirect      
N-Linked glycosylation of hemagglutinin (HA) has been demonstrated to regulate the virulence and receptor-binding specificity of avian influenza virus (AIV).  In this study, we characterized the variation trend of naturally isolated H9N2 viruses for the potential N-linked glycosylation sites in HA proteins, and explored any important role of some glycosylation sites.  HA genes of 19 H9N2 subtype AIV strains since 2001 were sequenced and analyzed for the potential glycosylation sites.  The results showed that the viruses varied by losing one potential glycosylation site at residues 200 to 202, and having an additional one at residues 295 to 297 over the past few years.  Further molecular and single mutation analysis revealed that the N200Q mutation lost an N-linked glycosylation at positions 200 to 202 of the HA protein and affected the human-derived receptor affinity.  We further found that this N-linked glycosylation increased viral productivity in the lung of the infected mice.  These findings provide a novel insight on understanding the determinants of host adaption and virulence of H9N2 viruses in mammals.
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