Metabolic Status during Germination of Nano Silica Primed Zea mays Seeds under Salinity Stress

Journal of Crop Science and Biotechnology - Priming is a safe, easy, and effective way to increase plant tolerance against stress. This research aims to study the metabolic status of the...     

Evaluation of finger weeder safety and efficacy for intra-row weed removal in irrigated field crops

Increased demand for pesticide-free food and the development of herbicide-resistant weed populations have created a need for non-chemical weed-control tools. A candidate mechanical tool for controlling weeds in the seeding line (intra-row zone) is the finger weeder. This study thus aimed to evaluate the safety and weed-control efficacy of the finger weeder in various irrigated field crops. Eight field trials were conducted in processing tomato, sweet corn, sunflower, cotton, and beetroot over 2 years. The finger weeder treatments were applied as the sole weed-control method (single or double treatments) and in combination with herbicides. A mini meta-analysis was used to evaluate the overall effect of the finger weeder treatments on crop stand and yield and on weed control efficacy. Weed density in the control not treated with herbicides nor a finger weeder ranged between 2 and 62 weeds m⁻². The finger weeder treatments resulted in a significant reduction in weed density, which ranged between 40% and 90%. The weed density following the double finger weeder treatment was not significantly different from that for the conventional herbicide-based treatment (p = 0.32) and could therefore be considered as an effective environmentally friendly alternative. Furthermore, a single FW treatment integrated with herbicide application gave better weed control than the conventional herbicide treatment (p = 0.04). This treatment was safe for the crops with no significant stand (p = 0.19) or yield (p = 0.29) reductions compared to commercial treatment. The results of this study demonstrate the promise of the finger weeder as an effective tool within integrated weed management systems for conventional agro-systems. The tool offers a rational weed-control solution for sustainable systems under irrigation.     

Three<Emphasis Type="Italic">Orobanche</Emphasis> species newly found on crops in israel

Orobanche amethystea Thuill.,O. loricata Reichenb. andO. pubescens D’Urv. were found to parasitize the roots of cultivated plants in Israel.Orobanche pubescens is known from the local flora, and was now found to cause damage in parsley fields and toTropaeolum majus L. (nasturtium) in ornamental gardens.Orobanche amethystea andO. loricata are known as occasional weeds in Europe and were recently found for the first time in Israel.Orobanche amethystea densely populated vetch fields in Israel, andO. loricata was found in ornamental gardens. A key for the identification ofOrobanche species in cultivated areas in Israel is given, based on morphological features. http://www.phytoparasitica.org posting Jan. 13, 2002.     

西门塔尔牛胰腺间充质干细胞原代培养及其多向分化潜能研究

旨在对西门塔尔牛胰腺间充质干细胞（pancreatic mesenchymal stem cells,PMSCs）进行原代培养并研究其体外分化潜能,为细胞疗法和组织工程学方面提供新的种子细胞。本研究从3月龄的西门塔尔牛胚胎中无菌分离胰腺组织,分别采用胶原酶消化法和组织块贴壁法分离PMSCs,进行原代培养;绘制第3代、第9代、第15代细胞生长曲线并测定群体倍增时间及克隆形成能力,采用免疫荧光检测干细胞表面标志物（CD29、CD44、CD73、CD90、CD34和CD45）,RT-PCR检测干细胞细胞表面标志物（CD29、CD44、CD73、CD90、CD106、CD166、CD34和CD45）;染色体核型分析检测其基因稳定性,通过向成脂、成骨、成软骨和成肝样细胞诱导分化,检测其多向分化潜能。结果表明,两种方法都可成功分离出PMSCs,细胞贴壁后形态均为长梭形,漩涡状生长,生长趋势呈典型的S形;第9代细胞群体倍增时间显著低于第15代而高于第3代（P<0.01）;第9代PMSCs克隆形成率显著低于第3代而显著高于第15代（P<0.05）;免疫荧光结果表明,PMSCs特异性表达CD29、CD44、CD73和CD90,RT-PCR结果显示PMSCs特异性表达CD29、CD44、CD73、CD90、CD106和CD166,未表达造血细胞表面标志物CD34和CD45,与国际细胞治疗学会组织干细胞委员会指定的MSCs表面标记物相对应;核型分析表明,PMSCs为正常二倍体（2n=60,XY）,染色体基因组未发生变异;特异性染色和RT-PCR结果表明,从西门塔尔牛体内获得的PMSCs可分化为脂肪细胞、骨细胞、软骨细胞和肝样细胞。本试验证实两种方法均可成功建立西门塔尔牛PMSCs体外分离培养体系,PMSCs具有活性好、增殖速度快的特点,与MSCs有相似的生物学特性和多项分化的潜能。可为组织工程学提供新的种子细胞。     

Black nightshade (<Emphasis Type="Italic">Solanum nigrum</Emphasis>) emergence and development is affected by seed density and burial depth

Black nightshade (Solanum nigrum L.) is a troublesome weed worldwide, affecting a large number of crops. As weed development is affected by a variety of factors, advanced knowledge on the plant’s biological and ecological qualities can support favorable management strategies. Seed density is an ecological factor affecting emergence and early growth of many weed species. For that reason, the current study characterizes and quantifies the seed density impact on black nightshade seedling-emergence and early growth, and the interaction between seed density and burial depth on these growth parameters. Greenhouse studies conducted in 2005, 2006 and 2010 examined black nightshade seed densities of 1, 5, 10, 25 and 50 seeds per pot, buried at, 1, 2, 3, 4 and 5 cm. Impact of seed density on weed emergence and growth was characterized by number of emerged plants and leaves, followed by biomass measurements. Seed density had no impact on emergence at the tested burial depths. There was a strong logistic relationship (P < 0.001, and R ²  > 0.97) between time and emergence, and a strong linear relationship (P < 0.002 and R ²  > 0.86) between time and number of leaves produced in all depths and seed densities. A negative relationship was observed between seed density and plant development and growth rate. Results of this study extend the knowledge on black nightshade biology and support decision-making concerning rational weed management.     

基于聚乙烯袋水培法9个甜瓜品种对埃及列当的抗性鉴定

【目的】基于聚乙烯袋水培法研究甜瓜不同品种对列当的抗性鉴定方法,为甜瓜抗列当品种选育提供技术支撑。【方法】利用聚乙烯袋水培法,研究不同甜瓜品种根系分泌物对埃及列当种子萌发诱导活性及寄生的影响,评价甜瓜品种抗性。【结果】聚乙烯袋水培9个接种埃及列当种子的甜瓜品种,其根系分泌物都可刺激列当种子发芽,但瘤状茎数量差异显著。用瘤状茎数量评价9个甜瓜品种对埃及列当的抗性,结果表明,参试甜瓜品种对列当寄生的抗感性存在差异,k2-2、k2-7及CEZ这3个品种抗性优于其他品种。【结论】聚乙烯袋水培法可作为有效的甜瓜列当抗性室内鉴定方法。     

Response of wheat growth and productivity to exogenous polyamines under lead stress

Polyamines [i.e. spermine (Spm), spermidine (Spd) and putrescine (Put)] antagonistic effects on stress imposed by 2.0 mM lead (Pb²⁺) on growth, yield and its components and changes in the osmoprotectant and endogenous Pb²⁺ concentrations, the contents of some nutrients and tissue health in wheat plants were evaluated. Under the three applied polyamine (PAs) applications, the efficiency of wheat plants to tolerate Pb²⁺ stress in terms of growth and yield characteristics was noticed to varying degrees. The enhancements in osmoprotectant concentrations and plant health [in terms of relative water content (RWC) and membrane stability index (MSI)], and reductions in electrolyte leakage (EL) and plant Pb²⁺ concentration were correlated with the reasonable growth of Pb²⁺-stressed plants and their grain yield. Results point out that, better growth and yield characteristics, MSI, RWC, leaf photosynthetic pigment and osmoprotectant concentrations, and nutrient contents were obtained with seed soaking in 0.25 mM Spm, 0.50 mM Spd or 1.0 mM Put than those generated with seed soaking in water under 2.0 mM Pb²⁺ stress. In contrast, EL and the concentration of endogenous Pb²⁺ were significantly reduced. However, the Pb²⁺-free control positively exceeded the all stressed treatments. Among all tested PAs, 1.0 mM Put showed the best results and thus is recommended, as seed soaking, for wheat to grow well under Pb²⁺ stress.     

Evaluation of herbicides for selective weed control in grafted watermelons

Grafted watermelon is a combination of two plants, aCucurbita rootstock and a watermelon scion. Therefore, weed control for this crop faces a unique problem: the safety of the selected herbicide has to be tested for both plants that make up the grafted plant. In the current study, we evaluated the usage safety of selected herbicides forCucurbita rootstocks as well as for non-grafted and grafted watermelons, and the control ofAmaranthus retroflexus by the same herbicides. In addition, the residual effect of the herbicides was tested for seeded and transplanted melons representing the next crop following cultivation of the grafted watermelons. The herbicides ethalfluralin, pendimethalin, ethalfluralin, sulfentrazone, oxyfluorfen, chlorsulfuron and clomazone were chosen for their potential to controlA. retroflexus. Pendimethalin and trifluralin were less effective than the other herbicides in controllingA. retroflexus; sulfentrazone, chlorsulfuron and clomazone were not safe for use on the tested cucurbits and thus cannot be recommended for weed control in grafted watermelons. Therefore, by eliminating the herbicides that are toxic to cucurbits and those that are ineffective forA. retroflexus control, it was concluded that the herbicides ethalfluralin and oxyfluorfen can be considered effective and safe for weed control in grafted watermelons. It was shown that trifluralin and oxyfluorfen have the potential to be applied effectively through the drip irrigation system. http://www.phytoparasitica.org posting Jan. 10, 2008.     

Productivity,Respiration, and Light-Response Parameters of World Grassland and Agroecosystems Derived From Flux-Tower Measurements

Grasslands and agroecosystems occupy one-third of the terrestrial area, but their contribution to the global carbon cycle remains uncertain. We used a set of 316 site-years of CO₂ exchange measurements to quantify gross primary productivity, respiration, and light-response parameters of grasslands, shrublands/savanna, wetlands, and cropland ecosystems worldwide. We analyzed data from 72 global flux-tower sites partitioned into gross photosynthesis and ecosystem respiration with the use of the light-response method (Gilmanov, T. G., D. A. Johnson, and N. Z. Saliendra. 2003. Growing season CO₂ fluxes in a sagebrush-steppe ecosystem in Idaho: Bowen ratio/energy balance measurements and modeling. Basic and Applied Ecology 4:167–183) from the RANGEFLUX and WORLDGRASSAGRIFLUX data sets supplemented by 46 sites from the FLUXNET La Thuile data set partitioned with the use of the temperature-response method (Reichstein, M., E. Falge, D. Baldocchi, D. Papale, R. Valentini, M. Aubinet, P. Berbigier, C. Bernhofer, N. Buchmann, M. Falk, T. Gilmanov, A. Granier, T. Grünwald, K. Havránková, D. Janous, A. Knohl, T. Laurela, A. Lohila, D. Loustau, G. Matteucci, T. Meyers, F. Miglietta, J. M. Ourcival, D. Perrin, J. Pumpanen, S. Rambal, E. Rotenberg, M. Sanz, J. Tenhunen, G. Seufert, F. Vaccari, T. Vesala, and D. Yakir. 2005. On the separation of net ecosystem exchange into assimilation and ecosystem respiration: review and improved algorithm. Global Change Biology 11:1424–1439). Maximum values of the quantum yield (α=75 mmol · mol^?1), photosynthetic capacity (A_max=3.4 mg CO₂ · m^?2 · s^?1), gross photosynthesis (P_g,max=116 g CO₂ · m^?2 · d^?1), and ecological light-use efficiency (ε_ecol=59 mmol · mol^?1) of managed grasslands and high-production croplands exceeded those of most forest ecosystems, indicating the potential of nonforest ecosystems for uptake of atmospheric CO₂. Maximum values of gross primary production (8 600 g CO₂ · m^?2 · yr^?1), total ecosystem respiration (7 900 g CO₂ · m^?2 · yr^?1), and net CO₂ exchange (2 400 g CO₂ · m^?2 · yr^?1) were observed for intensively managed grasslands and high-yield crops, and are comparable to or higher than those for forest ecosystems, excluding some tropical forests. On average, 80% of the nonforest sites were apparent sinks for atmospheric CO₂, with mean net uptake of 700 g CO₂ · m^?2 · yr^?1 for intensive grasslands and 933 g CO₂ · m^?2 · d^?1 for croplands. However, part of these apparent sinks is accumulated in crops and forage, which are carbon pools that are harvested, transported, and decomposed off site. Therefore, although agricultural fields may be predominantly sinks for atmospheric CO₂, this does not imply that they are necessarily increasing their carbon stock.     

Characterization of midgut and salivary gland proteins of Hyalomma dromedarii females controlled by entomopathogenic nematodes

Biological control of hard ticks, Hyalomma dromedarii (Acari: Ixodidae) using entomopathogenic nematode of two families; Heterorhabditidae and Steinernematidae was studied. The protective effect of controlled ticks including haemolymph and haemocytes against these biological agents were also investigated. It was found that heterorhabditid strains cause a higher effect in biological control of engorged female H. dromedarii than those of stienernematid strains. It induced mortality rates ranged from 12-92% versus 4-88% for stienernematid strains. It was also found that these entomopathogenic nematodes can not reproduce within the exposed ticks. SDS-PAGE of proteins extracted from midguts and salivary glands infected with 4000 IJs tick(-1) separated 21 and 25 protein bands versus 13 and 19 protein bands from non-infected ones, respectively. It was concluded that entomopathogenic nematodes of family Heterorhabditidae proved to have a potential acaricidal effect in the control of hard ticks. Moreover, the controlled ticks released unknown proteins in their haemolymph that may promote the haemocytes to phagocyte the nematodes as a type of defense mechanism.