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Liu H.W.,China Agricultural University | Luo L.X.,China Agricultural University | Li J.Q.,China Agricultural University | Liu P.F.,China Agricultural University | And 2 more authors.
Plant Pathology | Year: 2014

Cucumber green mottle mosaic virus (CGMMV) is transmitted mechanically in cucurbits, but whether it is transmitted via pollen to healthy plants and onto the subsequent generation of seedlings is unknown. Greenhouse experiments were conducted to investigate the importance of this route of infection. Cucumber seedlings at the 3-true-leaf stage were mechanically inoculated with CGMMV. At anthesis, scanning electron microscopy (SEM) and reverse transcription polymerase chain reaction (RT-PCR) were used to verify the presence of CGMMV. Pollen was collected from the flowers of the infected plants and used to fertilize non-inoculated plants. The rate of CGMMV transmission to the resulting fruits ranged from 17·1 to 51·2% compared with 33·3-100% for mechanically inoculated plants. Seeds were harvested from the cucumber fruits of both treatments and tested for the presence of CGMMV by RT-PCR. The CGMMV-positive seeds harvested from the two treatments were sown separately. The seed transmission rates for the inoculated and non-inoculated plants were 16·7-100% and 12·8-76·7%, respectively. It was concluded that CGMMV can be transmitted both horizontally via cucumber pollen and vertically, to the next generation, in infected seeds. In addition the rate of seed transmission was much higher than previous reports. These findings have important implications for the disease management of CGMMV. © 2013 British Society for Plant Pathology. Source


Niu Y.,Beijing Forestry University | Niu Y.,Key Laboratory of Soil and Water Conservation and Desertification Combating of Ministry of Educ | Liu H.,Beijing Hydraulic Research Institute | Liu H.,Beijing Engineering Technique Research Center | And 4 more authors.
Paiguan Jixie Gongcheng Xuebao/Journal of Drainage and Irrigation Machinery Engineering | Year: 2013

In order to explore appropriate irrigation mode of melon, effect of drip irrigation with diffe-rent irrigation threshold on water utilization and biomass of melon in greenhouse were investigated. The low irrigation threshold was designed based on the proportion of irrigating substrate moisture content with the substrate feild capacity (FC), and treatments including 90% of FC(T1), 75% of FC(T2) and 60% of FC(T3). Results show that the lower irrigation threshold is good at increasing leaf area and stem diameter, but the plant height is not sensitive with it. The yield of T2 is the highest followed by T3 and T1. The root is distributed in a circle with a radius of 20 cm in the horizontal direction, and is distributed in the depth of 40 cm in the vertical direction. The water use efficiency (WUE) of T3 is the highest followed by T1 and T2. The highly efficient irrigation schedule is made with the value of crop factor (Kc) in different periods are 1.81, 1.61, 2.21 and 2.19. Source


Zhu C.,China Agricultural University | Zhu C.,Chinese Institute for the Control of Agrochemicals | Xie B.,Chinese Academy of Agricultural Sciences | Zheng J.,Beijing Plant Protection Station | Li J.,China Agricultural University
Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery | Year: 2011

A safe and reasonable application of pesticides expert system was designed with B/S structure which had six sub-systems such as pests querying, pest identifying, decision-making of control methods, pesticide recommendation, knowledge management and expert consulting. Ontology technology was applied to model expert knowledge in order to achieve high intelligent reasoning and the sharing, and the knowledge reusing. Furthermore, a multi-factor model of pesticide evaluation was designed for comprehensively considering various factors that affect the reasonable selection of pesticides. The implemented prototype system verified that the solution was low-cost, high scalable, user-friendly and efficient. It is widely prospective in various vegetable productions and will supply a guideline for other crops production. Source


Zhu X.,China Agricultural University | Chen X.,Beijing Plant Protection Station | Guo L.,China Agricultural University
Plant Disease | Year: 2011

In total, 455 Monilinia isolates from stone fruits collected from several provinces (cities) in China from 2003 to 2009 were identified to species based on morphological characteristics, molecular identification, and the sequence of the internal transcribed spacer (ITS) regions 1 and 2 and the 5.8S gene of the ribosomal RNA. Overall, four species were detected (Monilinia fructicola, M. fructigena, M. laxa, and Monilia polystroma). M. fructicola was the most prevalent (93.0%) followed by M. fructigena (4.8%), M. laxa (2.0%), and Monilia polystroma (0.2%). M. fructicola and M. fructigena were found on peach, plum, and apricot; M. laxa was found only on apricot, cherry (in an organic orchard), and wild peach; and Monilia polystroma was found only on plum in Heilongjiang. The pathogenicity of Monilinia fructicola, M. laxa, and M. fructigena did not significantly differ on wounded nectarine and apricot, indicating that the differences in frequency of occurrence were not linked to virulence. Phylogenetic analysis based on ITS sequences showed that the isolates of M. laxa and M. fructigena from China differed from isolates of these species from other countries, and that the difference led to the separation of the isolates from China and those from other countries into different phylogenetic groups. Further study is needed to determine whether they are cryptic species. © 2011 The American Phytopathological Society. Source


Wang X.,China Agricultural University | He X.,China Agricultural University | Herbst A.,Institute of Chemical Technology | Langenakens J.,AAMS Salvarani Bvba | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2014

The use of pesticides is an important part of modern agriculture and contributes to the productivity and the quality of the cultivated crop. Pesticide exposure via spray drift can have a negative impact on bystanders, residents, livestock, terrestrial and aquatic ecosystems. Several reviews related to drift phenomenon have been published since the negative effect of spray drift has been recognized. Spray drift is affected by environmental and meteorological conditions, the spray technique and the crop. Wind speed and wind direction are meteorological factors affecting spray deposition. Relative humidity and high air temperature can reinforce evaporation by decreasing the droplet size of particularly small spray droplets, subsequently decreasing their sedimentation velocity and making them more drift-prone. The fate of spray droplets is influenced by operating conditions such as application height, driving speed of sprayer, and nozzle spacing. Air-assisted spraying and use of shielded sprayers in general reduce spray drift. The use of an end nozzle at the edge of the field can prevent overspray of pesticides. A new equipment was developed to study spray drift of boom sprayer and to evaluate drift risk of different spray equipment in this study. ISO 22369-2-2010 had been proposed in which sprayers were classified based on the results of field tests conducted following the ISO 22866 Standard "Methods for field measurement of spray drift". However, this test required well defined and stable conditions of wind speed and wind direction with respect to the sprayer travel direction. As an alternative methodology to simplify the assessment of spray drift risk for different equipment, this study developed drift test system to assess the amount of drift generated by field boom sprayers. The system was expected to be an effective alternative for drift assessment when wind tunnel was unavailable. This study followed the ISO 22369-2-2010 standard to test the potential drift of different nozzles indoor. According to the international standard ISO 22369-2-2010, the spray drift potential of six kinds of fan nozzle (XR110-04, IDK120-03, IDK120-04, ID120-015, ID120-025, and ID120-05) were tested and evaluated indoor by measuring the drift loss and calculating the potential drift. The method could be used for direct evaluation of drift. In the test, BSF (1‰) tracers were used to test the droplet. The test showed that the droplet size and pressure were the main factors affecting drift loss (P<0.05). When the pressure was 0.3 MPa, the potential drift of XR110-04 was 33%, which was much higher than the other 5 kinds of nozzles. The potential drift loss of nozzle Lechler ID120-025 was only 6%, which was the minimum. The risk of spray drift was closely related with the spray pressure in this study. The result showed that as the spray pressure increased, the volume of the droplet diameter became smaller, which greatly increased the potential drift. The results can provide valuble information for the reduction of pesticide spray drift and drift classification. Source

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