施氮对苜蓿初花期光合日变化、叶片形态及干物质产量的影响

通过研究不同氮素水平下滴灌苜蓿叶片形态特征、光合日变化规律,分析不同施氮水平下滴灌苜蓿光合日变化、叶片形态与干物质产量的关系,以期进一步揭示施氮对紫花苜蓿干物质及产量形成的影响机制,进而为优化实际生产中紫花苜蓿的氮管理策略提供理论依据。采用单因素随机区组设计,设置0(CK)、60(N₁)、120(N₂)和180kg·hm^-2(N₃)共4个施氮水平,在紫花苜蓿初花期对光合日变化、叶片形态、叶片氮含量和苜蓿产量构成进行测定。结果表明,施氮处理下苜蓿的叶片净光合速率、蒸腾速率和水分利用效率均高于不施氮处理,施氮处理的苜蓿叶片胞间CO₂浓度低于不施氮处理。对净光合速率和蒸腾速率综合影响最大的环境因子是光合有效辐射。随着施氮量的增加,紫花苜蓿的叶长、叶宽、叶面积、比叶重,以及叶片干重、茎秆干重、干物质产量、叶片氮含量、淀粉和可溶性糖含量均呈先增加后降低的趋势。不同施氮水平下,对叶片形态结构影响最大的为叶面积,其次分别为比叶重、叶长和叶宽,对苜蓿干物质产量影响从大到小依次为叶片氮含量>...     

Production of polyclonal antiserum against recombinant VP28 protein and its application for the detection of white spot syndrome virus in crustaceans

The VP28 gene of white spot syndrome virus (WSSV) was cloned into pRSET B expression vector. The VP28 protein was expressed as a protein with a 6-histidine taq in Escherichia coli GJ1158 with NaCl induction. Antiserum was raised against this recombinant-VP28 protein in rabbits and it recognized VP28 protein in naturally and experimentally WSSV-infected shrimp, marine crabs, freshwater prawns and freshwater crabs. The antiserum did not recognize any of the other known WSSV structural proteins. Various organs such as eyestalks, head muscle, gill tissue, heart tissue, haemolymph, tail tissue and appendages were found to be good materials for detection of WSSV using the antiserum and detection of WSSV was successful in experimentally infected Penaeus monodon and P. indicus at 12 and 24 h post-infection (p.i.), respectively. The antiserum was capable of detecting WSSV in 5 ng of total haemolymph protein from WSSV-infected shrimp.     

白斑综合征病毒环介导等温扩增快速检测方法的建立

根据对虾白斑综合征病毒(WSSV)囊膜蛋白VP28基因保守序列,利用Primer Explorerv 4.0软件设计了4条引物,建立了白斑综合征病毒环介导等温扩增快速检测方法,对反应温度和反应时间等参数进行了优化,同时将建立的LAMP检测方法与巢式PCR进行了比较分析。结果表明,LAMP最适反应在64℃恒温条件60min内完成,凝胶电泳呈现梯型条带;反应体系中添加SYBR Green I荧光染料后,绿色的阳性结果明显区别于橙色阴性结果。LAMP方法的最低检出限为100拷贝/μL,灵敏度较巢式PCR高100倍,而且LAMP方法在1h内即可完成检测,操作简单,无需复杂仪器,肉眼可直接观察检测结果。用建立的LAMP方法对临床发病南美白对虾样品进行了检测,结果表明,LAMP方法适合对虾白斑综合征病毒的现场快速检测。     

中国海洋经济前景预测

中国海洋经济正处于快速发展阶段,加强海洋经济的预测研究将有利于认识海洋经济发展规律、确定全国海洋经济发展目标和实现海洋开发战略目标。文章主要运用趋势外推法和灰色系统理论构建海洋经济预测模型,利用历史统计数据,预测中国海洋经济的发展趋势。     

湖泊渔业资源开发的系统动力学模型研究

采用灰色系统理论与国际先进的人工神经网络模拟相结合的先进技术，进行了太湖、濑湖和金鸡湖的渔业资源开发的系统动力学模型研究。认为控制捕涝强度是调空太湖针银鱼，梅鲚，白虾３个主要经济种群的关键因素，专家鉴定认为，本研究填补国内空白，居国内领先水平。     

Improved micropropagation protocol and enhancement in biomass and chlorophyll content in Stevia rebaudiana (Bert.) Bertoni by using high copper levels in the culture medium

Incorporation of a range of higher concentrations of CuSO₄·5H₂O in MS medium [Murashige, T., Skoog, F., 1962. A revised medium for rapid growth and bioassay with 240 tobacco tissue cultures. Physiol. Plant 15, 473–497] significantly enhanced direct shoot bud induction and proliferation from cultured leaf and nodal explants taken from mature plants of Stevia rebaudiana. Shoot bud induction medium was supplemented with BAP (2.2 μM) and IAA (2.8 μM). When the concentration of CuSO₄·5H₂O in the induction medium was raised to 0.5 μM (five times the MS level, i.e. 0.1 μM) there was significant increase in percentage response along with increase in shoot bud number per explant. The shoots were healthy, well developed with dark green broader leaves. There was remarkable increase in total biomass and chlorophyll content at increased (0.5 μM) copper level in the medium. During proliferation stage also presence of high copper levels in the medium favoured increase in shoot bud number per explant.     

Does root-sourced ABA play a role for regulation of stomata under drought in quinoa (Chenopodium quinoa Willd.)

The Andean seed crop quinoa (Chenopodium quinoa Willd.) is traditionally grown under drought and other adverse conditions that constrain crop production in the Andes, and it is regarded as having considerable tolerance to soil drying. The objective of this research was to study how chemical and hydraulic signalling from the root system controlled gas exchange in a drying soil in quinoa. It was observed that during soil drying, relative g_s and photosynthesis A_max (drought stressed/fully watered plants) equalled 1, until the fraction of transpirable soil water (FTSW) decreased to 0.82 ± 0.152 and 0.33 ± 0.061, respectively, at bud formation, indicating that photosynthesis was maintained after stomata closure. The relationship between relative g_s and relative A_max at bud formation was represented by a logarithmic function (r² = 0.79), which resulted in a photosynthetic water use efficiency WUE_Amax_/gs$\text{WU}{\text{E}}_{A_{\text{max}}/g_{\text{s}}}$ of 1 when FTSW > 0.8, and increased by 50% with soil drying to FTSW 0.7–0.4. Mild soil drying slightly increased ABA in the xylem. It is concluded that during soil drying, quinoa plants have a sensitive stomatal closure, by which the plants are able to maintain leaf water potential (ψ_l) and A_max, resulting in an increase of WUE. Root originated ABA plays a role in stomata performance during soil drying. ABA regulation seems to be one of the mechanisms utilised by quinoa when facing drought inducing decrease of turgor of stomata guard cells.     

Mineral content of three olive cultivars irrigated with treated industrial wastewater

The reuse of saline treated industrial wastewater generated by textile firms mixed with municipal domestic effluent for irrigation was used to asses its effect on the mineral content of three olive (Olea europaea L.) cultivars under greenhouse and field conditions during two complete vegetative cycles. Chemical analysis of the treated wastewater indicated that the element concentrations fall within the permissible range of irrigation water used for plants. However, little impermissible accumulation of Na and Mg higher than the recommended maximum concentration was observed. Irrigation water with six electrical conductivities (EC = 0.78, 1.0, 2.0, 3.0, 4.0 and 5.0 dS m⁻¹ in treatments T₀, T₁, T₂, T₃, T₄, T₅, respectively) were compared in the greenhouse experiment. The olive trees in the field experiment were trickle irrigated with potable water and treated wastewater (average EC = 4.2 dS m⁻¹). The results of the greenhouse experiment showed that leaf N, Cu, Mn, Fe, Pb, and Na contents increased with increasing salinity of the treated wastewater. This increase was accompanied with a decrease in K and Mg contents. Leaf Ca and Cl concentrations were not considerably affected. Ion analysis in roots indicated that the contents of P, Na, Cl, Mn, and Pb increased while K decreased as treated wastewater salinity increased. Consequently, in most cases T₄ and T₅ gave a highly significant increase or decrease in accumulation of the previously mentioned minerals. A considerable variation in the studied cultivars was noticed. ‘Nabali’ was considered the most tolerant cultivar for the high salinity levels of the treated wastewater; its transporting selectivity of Na from root to leaf was higher and more Na was retained in the roots. Tissue analysis of leaves indicated that the element concentrations were within the adequate levels except those of Fe in ‘Nabali’ and ‘Manzanillo’, Na in ‘Improved Nabali’ and Cu in ‘Nabali’ and ‘Manzanillo’. In view of these findings, the negligible accumulation of minerals in leaves and roots indicated that this kind of textile effluent can be used as a valid alternative for irrigation of olive orchards with continuous monitoring of mineral levels.     

广东省水稻生产机械装备水平灰色预测与分析

利用广东省水稻生产主要环节机械装备保有量的历史数据,建立了灰色GM(1,1)预测模型,对2006-2020年广东省水稻生产机械装备水平进行了预测,并参考广东省水稻生产机械化作业水平值,对其预测结果进行了修正,以便能为政府主管部门制定提高水稻生产机械装备水平的政策措施提供参考依据.     

烟叶编持机的设计与开发

为了解决人工编烟费时、费力,效率低下的问题,设计开发了摆动钩针式烟叶编持机,设计编烟速度为12～20s/m可调,铺叶厚度和编叶数量可自动调整,综合辅助用工实际应用效率达手工编烟的5倍以上.编烟测试表明,该型编烟机编制均匀牢固,线迹美观,明显减少了编烟用工,具有较好的应用前景.