Effects of UV-B treatment on controlling lignification and quality of bamboo (Phyllostachys prominens) shoots without sheaths during cold storage

For evaluating the effects of UV-B treatment on lignification and quality of bamboo(Phyllostachys prominens) shoots during postharvest, fresh bamboo shoots without sheaths were irradiated with UV-B at a dose of 8.0 kJ m~(–2) and then stored at(6±1)℃ along with 85–90% relative humidity(RH) for 15 d. The results showed that UV-B treatment apparently slowed down the increase rates of flesh firmness, weight loss, and contents of cellulose and lignin. It also decreased the activities of 4-coumarate CoA ligase(4CL), peroxidase(POD), cinnamyl alcohol dehydrogenase(CAD) and phenylalanine ammonialyase(PAL) and the expression of their encoding genes during cold storage. It was suggested that these effects of UV-B treatment on decreases in these enzymatic activities and the expression of encoding genes might collectively regulate lignin synthesis and accumulation in the flesh of bamboo shoots and consequently benefit in maintaining the edible quality of bamboo shoots during cold storage.     

Local nitrogen application increases maize post-silking nitrogen uptake of responsive genotypes via enhanced deep root growth

Nitrogen (N) is unevenly distributed throughout the soil and plant roots proliferate in N-rich soil patches. However, the relationship between the root response to localized N supply and maize N uptake efficiency among different genotypes is unclear. In this study, four maize varieties were evaluated to explore genotypic differences in the root response to local N application in relation to N uptake. A split-root system was established for hydroponically-grown plants and two methods of local N application (local banding and local dotting) were examined in the field. Genotypic differences in the root length response to N were highly correlated between the hydroponic and field conditions (r>0.99). Genotypes showing high response to N, ZD958, XY335 and XF32D22, showed 50–63% longer lateral root length and 36–53% greater root biomass in N-rich regions under hydroponic conditions, while the LY13 genotype did not respond to N. Under field conditions, the root length of the high-response genotypes was found to increase by 66–75% at 40–60 cm soil depth, while LY13 showed smaller changes in root length. In addition, local N application increased N uptake at the post-silking stage by 16–88% in the high-response genotypes and increased the grain yield of ZD958 by 10–12%. Moreover, yield was positively correlated with root length at 40–60 cm soil depth (r=0.39). We conclude that local fertilization should be used for high-response genotypes, which can be rapidly identified at the seedling stage, and selection for “local-N responsive roots” can be a promising trait in maize breeding for high nitrogen uptake efficiency.     

Detection and molecular characterization of bovine leukemia virus in beef cattle presented for slaughter in Egypt

Bovine leukemia virus (BLV) is the etiological agent of enzootic bovine leukosis, the most common neoplastic disease of cattle worldwide and a serious problem for the cattle industry. Previous studies have shown the molecular prevalence of BLV and the coexistence of BLV genotype-1 and -4 in Egyptian dairy cattle; however, the molecular characteristics of BLV in Egyptian beef cattle are unknown. Therefore, we collected blood samples of 168 beef cattle from slaughterhouses in three governorates in Egypt. Based on BLV-CoCoMo-qPCR-2 targeting long terminal repeats and nested PCR targeting the env-gp51 gene, the BLV provirus infection rates were found to be 47/168 (28.0%) and 42/168 (25.0%), respectively. Phylogenetic analysis based on 501 bp of the BLV env-gp51 gene from 42 BLV isolates revealed that at least six distinctive strains (b, e, f, g, x, and z) were prevalent in cattle across the examined regions. Furthermore, phylogenetic analysis of the 420 bp sequence of the BLV env-gp51 region of the six strains against 11 known genotypes showed that the strains b, e, f, and g were clustered into genotype-1, and strains x and z were clustered into genotype-4. Our results also indicated that strains b and x exist in both dairy and beef cattle in Egypt. The present study is the first to detect and genotype BLV among beef cattle in Egypt.     

Presence of a Temperature Gradient Among Genital Tract Portions and the Thermal Changes Within These Portions Over the Estrous Cycle in Beef Cows

The aim of the present study was to describe the temperature of the different portions of the female genital tract and their relation to rectal temperature and to investigate the effect of steroid hormones profiles on these variables over the estrous cycle in cattle. Four nonpregnant Japanese Black cows were investigated daily over two successive estrous cycles using a digital thermometer with a long probe and rounded-end sensor to record the temperature of the rectum (RT), vagina (VT), cervix (CT), uterine body (UBT) and uterine horns (UHT). Blood samples were collected immediately before temperature recording to assay peripheral levels of progesterone (P₄) and estradiol-17β (E₂). Moreover, transrectal ultrasonography was carried out after temperature recording to monitor the ovulatory follicle and track ovulation. During the experiment, the ambient temperature and relative humidity were recorded for further calculation of the temperature humidity index (THI). The temperature within the genital tracts in these cows progressively increased towards the uterine horns from the vagina. The VT, CT, UBT and UHTs were significantly higher in association with peripheral P₄ concentrations greater than 4 ng/ml (mid-luteal phase) when compared with lower peripheral P₄ concentrations. The VT was more significantly (P<0.01) correlated to the CT, UBT and UHTs than RT. In conclusion, a temperature gradient was present among the vagina, cervix and uterus over the estrous cycle, and changes in peripheral P₄ concentrations were associated with the thermal variations within these portions. The VT could be more beneficial than RT in monitoring temperature of deeper portions of the female genital tract in bovine.     

Symptom remission in spiked sandal trees by infusion of tetracycline antibiotics

Spike disease of sandal has recently been recorded in Kerala. For chemotherapy of the diseased trees a gravity-flow infusion technique was used to compare tetracycline compounds. All the compounds, including doxycycline and oxytetracycline, were effective when 500 mg per tree was infused in 500 ml water, but disease remission lasted for 4 months only. Repeated infusions failed to give complete remission. Increasing the concentration of tetracycline to 4–8 g per tree gave remission for 7–8 months; at 12 g per tree, phototoxicity was observed.     

荒漠土壤成分对陆面过程的影响研究

采集塔克拉玛干沙漠北缘肖塘观测站附近的土壤,应用Mastersizer-2000激光粒度仪测定土壤粒径,按照伍登-温德华粒级标准进行土壤成分分类,发现土壤类型并非均质沙土,在0~30 cm深度的浅层存在10%~24%的黏土,根据土壤成分比例对Noah陆面模式的土壤参数重计算,然后利用肖塘站2011年3月22日至7月25日的观测数据驱动Noah模式,对比修正土壤参数前后的模拟效果。结果表明：更新土壤参数后10 cm土壤温度模拟偏差减少0.62 ℃,土壤热通量偏差减小10.47 W·m-2,感热通量偏差减少7.02 W·m-2,地表净辐射偏差减少5.48 W·m-2,且效率系数达到更高的接受程度。通过泰勒图分析了土壤参数修正对Noah模拟效果的整体作用,表明修正土壤参数后的模式中热量传输扩散有一定的优化作用,10 cm土壤温度和热通量土壤温度模拟效果得到改进。     

黄河三角洲人地关系协调度时空演变及其驱动机制

黄河三角洲是黄河流域典型的生态环境脆弱区,在黄河流域生态保护与高质量发展的要求下,定量评价区域人地关系对黄河三角洲生态环境修复与经济发展有重要意义。基于1998—2018年遥感影像数据,运用耦合协调度模型、地理探测器等方法,分析了20年间黄河三角洲人地协调度时空演变特征,探讨了人地协调度空间演变特征及其驱动机制。结果表明：(1) 1998—2018年黄河三角洲人地协调度大致呈由内陆向沿海逐渐递减的空间分布特征,人地关系失调区域面积不断下降,协调区域面积不断上升,人地关系逐步缓和。主要协调水平为良好协调,区域面积达2 847.57 km²;各乡镇人地协调度等级呈自黄河流域向两岸地区递减的特征,各乡镇协调水平不断上升且差异显著但逐步缩小,极差值缩减至0.24,六合镇、胜坨镇、垦利街道和永安镇协调水平增长最为显著,分别上升了0.27,0.26,0.25,0.24;(2)因子探测器结果表明人均水资源、年均降水量、植被覆盖率与人口数量对人地协调度的解释力较高,经济发展水平、自然资源禀赋与自然环境特征在人地协调演进过程中的重要程度逐步上升;(3)研究时段内各因子间交互作用对人...