微RNA (microRNAs,miRNA)、小干扰RNA (small interfering RNA,siRNA) 是真核生物体内触发RNA干扰 (RNA interference,RNAi) 的两种非编码小RNA。两种非编码RNA生物合成通路在黑腹果蝇、埃及伊蚊、家蚕以及其他昆虫中具有广泛研究，但在膜翅目昆虫尤其是寄生蜂中少见。蝶蛹金小蜂是蝴蝶蛹期寄生蜂。本研究通过蝶蛹金小蜂基因组对miRNA、siRNA合成通路鉴定并分析。结果表明除siRNA通路中R2D2、Argonaute-2基因在基因组中分别具有2、3个拷贝，两个通路其他关键基因均只有1个拷贝。结构域保守性分析表明蝶蛹金小蜂相关蛋白与其他物种同源蛋白具有相似结构。对膜翅目昆虫Dicer、Argonaute基因进化分析表明siRNA通路相关基因进化速率更快。但与其他膜翅目昆虫相反，蝶蛹金小蜂中Dicer-2基因进化速率比Dicer-1基因更低。表达分析显示miRNA通路基因在蝶蛹金小蜂成虫中表达量更高而siRNA通路基因表达模式各不相同。本研究为了解寄生蜂miRNA、siRNA生物合成通路及其作用机制提供新的认识。

精准扶贫是中国全面建设小康社会、实现中华民族伟大“中国梦”的重要保障。产业扶贫是精准扶贫“五个一批”工程的重头戏，也是其他扶贫措施取得实效的重要基础。本文基于可持续生计框架，采用综合评价方法测度农户的生计资本，进而利用PSM-DID方法估计产业扶贫对农户生计资本的影响效应。结果显示，产业扶贫对农户生计资本有显著的正向影响，能显著提升农户的人力资本、社会资本和金融资本，但对自然资本和物质资本的影响不显著。产业扶贫对农户生计资本的影响具有异质性，对非贫困户的影响显著于贫困户。另外，产业扶贫对农户生计资本的影响也存在地区差异，对贵州农户的影响大于四川，但对甘肃农户的影响不显著。针对以上结论，未来需要通过加大人力资本培育力度、增强金融资本创新手段、发挥社会资本引导作用等提高农户的可持续生计，同时更要加大对贫困户的产业扶持力度。

研究表明氮肥深施能够减少稻田中氮素淋失、提高氮肥利用率；然而，我们对于稻田土壤微生物，特别是微生物中的丰富物种和稀有物种对于氮肥深施的响应知之甚少，而这一过程对于我们理解农业生态系统的生物多样性和功能至关重要。在本研究中，我们利用二代测序技术和生态模型理论，研究了不同氮肥施用条件下水稻根际土壤中丰富和稀有类群在水稻生长4个阶段的多样性模式及其组装机制。结果显示，在水稻根际土壤中丰富物种和稀有物种具有不同的分布模式：丰富物种广泛存在于各样品中，而稀有物种不是普遍存在的。随机过程在丰富菌群和稀有菌群的群落构建过程中均起着主导作用，其中扩散限制在丰富菌群中起着更重要的作用，而漂移等非主导过程在稀有菌群中起着更重要的作用。扩散限制对氮肥深施下丰富物种和稀有物种的影响高于不施氮肥和传统撒施；然而均值扩散对不施氮肥和传统撒施下稀有物种的影响高于氮肥深施处理。网络分析表明，与稀有物种相比，丰富物种相互之间连接紧密且占据网络的中心位置。尽管如此，大部分的关键物种由稀有物种组成，它们可能在维系网络稳定过程中发挥重要作用。总之，我们的研究结果突出了氮肥深施下根际土壤中丰富菌群和稀有菌群生态机制和共发生模式。

一方面，中国亚热带红壤区水稻土母质和肥力水平多变；另一方面，细菌多样性和群落组成在土壤生态系统过程和功能中发挥关键作用。但是水稻土的母质和肥力对细菌多样性和群落组成的影响如何仍不清楚，不同母质和肥力水平条件下驱动水稻土细菌多样性、群落组成和特异微生物种群变化的关键因素尚不明确。因此，本研究采集亚热带红壤区具有不同母质（第四纪红黏土或第三纪红砂岩）和不同肥力水平（高肥力或低肥力）的典型样地水稻土样品，通过454高通量测序测定细菌16S rRNA基因的V4−V5区，分析细菌多样性指数和群落组成变化。采用two-way ANOVA和two-way PERMANOVA探明母质和肥力对细菌多样性和群落组成的影响；主坐标分析（PCoA）、冗余分析（RDA）和多元回归树分析（MRT）明确细菌群落的变化，以及驱动该变化的关键土壤因子；共现网络分析阐明属水平特异细菌种群和关键土壤因子的关系；宏基因组差异分析工具（STAMP）确定不同土壤样品间差异物种。结果显示，母质和肥力对水稻土细菌多样性指数变化的贡献相似。但是肥力水平对细菌群落组成的影响要远大于母质。土壤因子，特别是土壤质地与细菌多样性指数密切相关。RDA分析发现土壤有机碳（SOC）是影响细菌群落组成的首要因素，并且25.5 g kg⁻¹有机碳含量是驱动高肥力和低肥力土壤细菌群落组成分异的关键阈值。共现网络分析暗示高肥力水平下，由于土壤环境的改善，细菌趋向于合作关系，并且富营养型细菌占主导地位。STAMP分析发现高肥力水稻土中Massilia和Rhodanobacter等富营养型细菌大量富集；而低肥力土壤中Anaerolinea等贫营养型细菌占主导。研究结果表明，不同母质和肥力水稻土中，土壤质地影响细菌多样性指数变化；而养分水平，特别是有机碳水平决定细菌群落组成的变化。

褐藻寡糖是一种功能性海洋寡糖，由褐藻胶经酶解得到，由β-1，4-甘露糖醛酸（M）和α-1，4-古洛糖醛酸（G）链接起来的不规则低分子聚合物。褐藻寡糖粘度较低、水溶性强；此外，它还具有抗氧化、免疫调节、抗细菌和炎症等多种生物学活性，在医学科学、功能食品、绿色农业等领域有着广泛的应用。虽然我们对褐藻寡糖的研究相对缺乏，但它作为一种新型生物饲料添加剂应用于畜牧业生产中，前景广阔。本文综述了褐藻胶的来源、褐藻寡糖的化学组成、制备方法与生物学活性，以及在畜禽上的应用，为后续褐藻寡糖的深入研究和未来在产业上的应用奠定基础。

The optimized nitrogen fertilization location differs in different rice-growing regions.  We optimized nitrogen deep-point application in root-growing zone (NARZ) for transplanted rice in subtropical China.  Field plot experiments were conducted over two years (2014–2015) in a double-rice cropping system to evaluate the effects of nitrogen (N) fertilizer location on grain yield and N use efficiency (NUE).  Four different nitrogen deep-point application methods (DN) were compared with traditional broadcast application (BN) using granular urea.  The results showed that grain yield,  recovery efficiency of N (RE_N), agronomic efficiency of N (AE_N), and partial factor productivity of N (PFP_N) significantly increased 10.3–63.4, 13.7–56.7, 24.7–201.9 and 10.2–63.4%, respectively, in DN treatment compared to BN, respectively.  We also find that DN treatments increased grain yield as well as grain N content, and thus grain quality, in comparison with conventional BN treatment.  Correlation analysis indicated that significant improvement in grain yield and NUE mainly resulted from increases in productive panicle number and grain N content.  In our proposed NARZ method, granular urea should be placed 0 to 5 cm around the rice seeding at a 12-cm depth druing rice transplanting.  In NARZ, balanced application of N, P and K further improved grain yield and NUE over treatments with a single N deep-point application.  High N uptake by the rice plant did not cause significant soil fertility depletion, demonstrating that this method could guarantee sustainable rice production.    
 

Chinese chive usually develops an off-flavor after a short storage time.  To explore effective ways to maintain the postharvest quality of Chinese chive, the effect of exogenous application of 6-benzylaminopurine (6-BA) on postharvest quality and antioxidant activity of chive was evaluated, and the mechanism of the physiological responses of chive to 6-BA treatment was explored.  Chives were sprayed for 10 min with 100, 300, or 500 mg L^–1 6-BA or with alkaline solution as the control, then stored at (2±1)°C with a relative humidity (RH) of 80–85%.  We found that 300 mg L^–1 6-BA significantly delayed yellowing and chlorophyll degradation, maintained the total phenolic and flavonoid content, and improved the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD).  In conclusion, we identified exogenous application of 6-BA as an effective method for maintaining postharvest quality of Chinese chive.  In addition, our finding that the activities of antioxidant enzymes increase in response to exogenous 6-BA provides new insights into the mechanism of cytokinin-based postharvest fresh-keeping. 

We have had little understanding on the effects of different types and quantities of biochar amendment on soil N transformation process and the microbial properties. In this study, various biochars were produced from straw residues and wood chips, and then added separately to a paddy soil at rates of 0.5, 1 and 2% (w/w). The effects of biochar application on soil net N mineralization and nitrification processes, chemical and microbial properties were examined in the laboratory experiment. After 135 d of incubation, addition of straw biochars increased soil pH to larger extent than wood biochars. The biochar-amended soils had 37.7, 7.3 and 227.6% more soil organic carbon (SOC), available P and K contents, respectively, than the control soil. The rates of net N mineralization and nitrification increased significantly as biochars quantity rose, and straw biochars had greater effect on N transformation rate than wood biochars. Soil microbial biomass carbon increased by 14.8, 45.5 and 62.5% relative to the control when 0.5, 1 and 2% biochars (both straw- and wood-derived biochars), respectively, were added. Moreover, biochars amendments significantly enhanced the concentrations of phospholipid fatty acids (PLFAs), as the general bacteria abundance increased by 161.0% on average. Multivariate analysis suggested that the three rice straw biochar (RB) application levels induced different changes in soil microbial community structure, but there was no significant difference between RB and masson pine biochar (MB) until the application rate reached 2%. Our results showed that biochars amendment can increase soil nutrient content, affect the N transformation process, and alter soil microbial properties, all of which are biochar type and quantity dependent. Therefore, addition of biochars to soil may be an appropriate way to disposal waste and improve soil quality, while the biochar type and addition rate should be taken into consideration before its large-scale application in agro-ecosystem.

Traditional agricultural systems have contributed to food and livelihood security. Rice-crab coculture (RC) is an important eco-agricultural process in rice production in northern China. Recognizing the soil fertility in RC may help develop novel sustainable agriculture. Soil carbohydrates are important factors in determining soil fertility in different culture modes. In this study, soil carbohydrates were analyzed under three different culture modes including rice monoculture (RM), conventional rice-crab coculture (CRC) and organic rice-crab coculture (ORC). Results showed that the contents of soil organic carbon and carbohydrates were significantly higher in the ORC than those in RM. The increasing effect was greater with increased organic manure. Similar tendency was found in CRC, but the overall effect was less pronounced compared with ORC. Carbohydrates were more sensitive to RC mode and manure amendment than soil organic carbon. Compare to RM, the (Gal+Man)/(Ara+Xyl) ratio decreased in all the RC modes, indicating a relative enrichment in plant-derived carbohydrates due to the input of crab feed and manure. While the increasing (Gal+Man)/(Ara+Xyl) ratio in ORC modes with increased organic manure suggested that crab activity and metabolism induced microbially derived carbohydrates accumulation. The lower GluN/MurA ratio in ORC indicated an enhancement of bacteria contribution to SOM turnover in a short term. The findings reveal that the ORC mode could improve the quantity and composition of soil carbohydrates, effectively, to ensure a sustainable use of paddy soil.

A field experiment with rice-rice rotation was conducted since 2002 in southeast China for investigating the response of soil microbial properties to intensive nitrogen fertilizer application. The tested soil was a subtropical paddy soil derived from Quaternary red clay. Differences between treatments existed in different application rates of urea when the experiment was designed. Urea was applied in five rates, i.e., 0, 0.5, 1, 1.5, and 2 U, equivalent to 0, 0.5, 1, 1.5, and 2 times the local average amount of urea application (900 kg urea ha-1 yr-1, equivalent to 414 kg N ha-1 yr-1). In 2007, soil total nitrogen, available nitrogen, and soil organic carbon contents were increased by 10.2-27.9, 8.0-16.0, and 10.2-30.6%, respectively, in treatments with urea application rates of 0.5 to 2 U compared to control (0 U). Microbial biomass carbon and nitrogen were also increased by 3.1-30.8 and 1.3-13.9%, respectively, in treatments with urea application. Basal respiration in treatments with urea input were 9.4-29.1% higher than that in control. However, changes of bacterial functional diversity had different trends. Urea fertilization enhanced bacterial functional diversity until treatment of 1 U, but re-decreased it from treatment of 1.5 U. Principal components analysis indicated that there were intimate relationships among soil organic matter, nitrogen nutrient, microbial biomass, and respiration. Nevertheless, microbial diversity was related to soil moisture contents after urea application. We conclude here that the application of N fertilizer improved soil microbial biomass and respiratory activity. But, microbial diversity was reduced when excessive urea was applied in the tested paddy soil.