Dynamics of ecosystem carbon stocks during vegetation restoration on the Loess Plateau of China

In the last few decades, the Loess Plateau had experienced an extensive vegetation restoration to reduce soil erosion and to improve the degraded ecosystems. However, the dynamics of ecosystem carbon stocks with vegetation restoration in this region are poorly understood. This study examined the changes of carbon stocks in mineral soil(0–100 cm), plant biomass and the ecosystem(plant and soil) following vegetation restoration with different models and ages. Our results indicated that cultivated land returned to native vegetation(natural restoration) or artificial forest increased ecosystem carbon sequestration. Tree plantation sequestered more carbon than natural vegetation succession over decades scale due to the rapid increase in biomass carbon pool. Restoration ages had different effects on the dynamics of biomass and soil carbon stocks. Biomass carbon stocks increased with vegetation restoration age, while the dynamics of soil carbon stocks were affected by sampling depth. Ecosystem carbon stocks consistently increased after tree plantation regardless of the soil depth; but an initial decrease and then increase trend was observed in natural restoration chronosequences with the soil sampling depth of 0–100 cm. Moreover, there was a time lag of about 15–30 years between biomass production and soil carbon sequestration in 0–100 cm, which indicated a long-term effect of vegetation restoration on deeper soil carbon sequestration.     

Soil microbial characteristics and yield response to partial substitution of chemical fertilizer with organic amendments in greenhouse vegetable production

Greenhouse vegetable production has been characterized by high agricultural inputs, high temperatures, and high cropping indexes. As an intensive form of agriculture, nutrient cycling induced by microbial activities in the greenhouses is relatively different from open fields in the same region. However, the responses of soil microbial biomass carbon (MBC) and nitrogen (MBN), enzyme activities, microbial community composition, and yield to organic amendment are not well understood. Therefore, a 5-year greenhouse tomato (Solanum lycopersicum Mill.)-cucumber (Cucumis sativus L.) rotation experiment was conducted. The field experiment comprised 5 treatments: 4/4CN (CN, nitrogen in chemical fertilizer), 3/4CN+1/4MN (MN, nitrogen in pig manure), 2/4CN+2/4MN, 2/4CN+1/4 MN+1/4 SN (SN, nitrogen in corn straw) and 2/4CN+2/4SN. The amounts of nitrogen (N), phosphorus (P₂O₅), and potassium (K₂O) were equal in the five treatments. Starting with the fourth growing season, the optimal yield was obtained from soil treated with straw. MBC, MBN, phospholipid fatty acid (PLFA) profiles, and enzyme activities were significantly changed by 5 years of substitution with organic amendments. Redundancy analysis showed that MBC accounts for 89.5 and 52.3% of the total enzyme activity and total community variability, respectively. The activities of phosphomonoesterase, N-acetyl-glucosaminidase, and urease, and the relative abundances of fungi, actinomycetes, and Gram-negative bacteria were significantly and positively related to vegetable yields. Considering the effects of organic amendments on soil microbial characteristics and vegetable yield, 2/4CN+1/4MN+1/4SN can improve soil quality and maintain sustainable high yield in greenhouse vegetable production.     

Effects of variety and chemical regulators on cold tolerance during maize germination

Maize growth and development is affected by low temperature(LT) especially at the early stages of development. To describe the response of different varieties to LT stress and determine an effective method to cope with LT stress, maize hybrids Zhengdan 958(ZD 958) and Danyu 39(DY 39) were planted and grown at 10 and 25°C, respectively. Effects of the chemicals potassium chloride(KCl), gibberellin(GA_3), 2-diethylaminoethyl-3,4-dichlorophenylether(DCPTA), and all three combined chemicals(KGD) on coping with LT stress were tested by seed priming. The varieties performed significantly different at 10°C. Compared to leaf, root growth was more severely affected by LT stress. Root/leaf ratio is likely a more reliable parameter to evaluate cold tolerance based on its close correlation with leaf malondialdehyde(MDA) content(R=–0.8). GA_3 advanced seed germination by about 2 days compared with control treatment of water. GA_3 and DCPTA both resulted in lower leaf MDA content and higher leaf and root area, and root/leaf ratio. KCl resulted in the highest evenness of plant height. KGD performed the best in increasing cold tolerance of maize morphologically and physiologically. Strategies to increase maize tolerance of cold stress, such as variety breeding or chemical selection, would increase maize yield especially at high-latitude regions and have great implications for food security.     

山茶褪绿矮缩伴随病毒杭州分离物的序列和进化分析

Through sequencing and assembly of small RNAs, a Camellia chlorotic dwarf-associated virus (CaCDaV) was identified on a camellia plant showing chlorosis and distorting leaves from Hangzhou (CaCDaV-HZ1). The full genome of CaCDaV-HZ1 was determined and compared with that of a CaCDaV isolate from Chongqing (CaCDaV-CA1). Results showed that they shared 85.7% overall nucleotide sequence identity. Insert and delete mutations were mainly distributed in the non-coding region, whereas the coding regions mainly contained synonymous substitution. All genes except V3 have identical length among the two isolates. Additionally, the small RNA profile of CaCDaV-HZ1 was also analysed and results showed that 24 nt is the major class of viral-derived siRNA indicating that methylation is a major resistance mechanism of camellia plants against geminiviruses.     

海南省芒果主产区主栽品种果实品质特性分析

[目的]明确海南省四大芒果产区(三亚、乐东、东方、昌江)两大芒果品种(台农、贵妃)果实的品质特性,为芒果果实品质评价及品种选育提供参考依据.[方法]采用2,6-二氯靛酚滴定、酸碱滴定、HPLC等方法测定76份芒果样品的单果重、果形指数、可食率、可溶性糖、蔗糖、果糖、葡萄糖、甜度值、可溶性固形物(TSS)、维生素C(Vc)、总酸、糖酸比、固酸比等13个品质指标,并进行相关性和主成分分析.[结果]台农果实的TSS、可溶性糖、蔗糖、果糖、葡萄糖、总酸含量及甜度值、糖酸比、固酸比平均值均高于贵妃,贵妃果实的单果重、果形指数、可食率和Vc含量平均值均高于台农.不同产区同一品种芒果果实的TSS、可溶性糖、蔗糖、葡萄糖、果糖和Vc含量及甜度值差异显著(P<0.05);单果重、果形指数、可食率、总酸含量及糖酸比、固酸比差异不显著(P>0.05).13个品质指标的部分指标间存在正相关或负相关,同时主成分分析将13个品质指标综合为4个主成分(PC1、PC2、PC3、PC4),累积方差贡献率达85.078%,能够代表原品质性状的绝大部分信息,其中乐东台农PC1、昌江贵妃PC2、三亚贵妃PC3和PC4因子得分最高.[结论]台农和贵妃果实均具有鲜明的品质特征,贵妃口感酸甜,台农口感更甜;乐东的台农、三亚和昌江的贵妃果实品质特性更佳.     

不同桑叶提取物对小鼠脾脏淋巴细胞增殖能力的影响

试验旨在比较不同桑叶提取物对小鼠脾脏淋巴细胞增殖作用的影响。用不同浓度乙醇醇沉桑叶水提物,制备桑叶粗多糖MLP-1、MLP-2、MLP-3、MLP-4、MLP-5,采用苯酚硫酸法测定各提取物多糖含量。以5种桑叶粗多糖和桑叶水提物（MLAE）为试验药物,采用MTT法比较多糖含量分别在15.625、31.25、62.5、125、250 μg/mL浓度时各提取物单独刺激及协同LPS、PHA共同刺激小鼠脾脏B、T淋巴细增殖的变化。结果显示,多糖浓度在15.625~250 μg/mL范围内,各提取物无论单独还是协同LPS和PHA时均能促进小鼠脾脏B、T淋巴细胞的增殖,其中,MLP-1多糖含量在低浓度时能显著刺激脾脏B淋巴细胞增殖（P<0.05）;MLP-3和MLP-5在低浓度时表现出较强的刺激T淋巴细胞增殖的能力;MLAE协同LPS在大部分浓度点的脾脏B淋巴细胞的增殖能力均显著高于细胞对照组和LPS对照组,可显著提升体液免疫功能（P<0.05）。     

建兰花叶病毒TGBp1自身互作研究

建兰花叶病毒(cymbidium mosaic virus,Cym-MV)是危害兰花生产的重要病毒之一.CymMV属于马铃薯X病毒属(Potexvirus),基因组为正单链RNA,包含5个开放阅读框(open reading frames,ORFs);ORF 1编码依赖RNA的RNA聚合酶(RNA-dependent ...     

山茶褪绿矮缩伴随病毒杭州分离物的序列和进化分析

<正>双生病毒(Geminivirus)是一类基因组为单链环状DNA的植物病毒,具有孪生的病毒粒子。国际病毒分类委员会(International Committee on Taxonomy of Viruses,ICTV)最新的分类报告将双生病毒分为9个属[1]。随着测序技术的发展,利用小RNA或转录组测序可鉴定植物中的已知和未知病毒,新的双生病毒也不断被发现和鉴定[2]。山茶褪绿矮缩伴随病毒(Camellia chlorotic dwar     

郑单系列玉米品种对我国玉米育种和生产的推动效应分析

阐述了郑单958等4个对我国玉米产业发展有较大影响的郑单系列玉米品种选育的过程,分析了郑单系列玉米品种对我国玉米育种和生产的推动效应,并对今后郑单系列玉米品种的发展进行了探讨。