Occurrence and diversity of Xanthomonas campestris pv. campestris in vegetable brassica fields in Nepal

Black rot caused by Xanthomonas campestris pv. campestris was found in 28 sampled cabbage fields in five major cabbage-growing districts in Nepal in 2001 and in four cauliflower fields in two districts and a leaf mustard seed bed in 2003. Pathogenic X. campestris pv. campestris strains were obtained from 39 cabbage plants, 4 cauliflower plants, and 1 leaf mustard plant with typical lesions. Repetitive DNA polymerase chain reaction-based fingerprinting (rep-PCR) using repetitive extragenic palindromic, enterobacterial repetitive intergenic consensus, and BOX primers was used to assess the genetic diversity. Strains were also race typed using a differential series of Brassica spp. Cabbage strains belonged to five races (races 1, 4, 5, 6, and 7), with races 4, 1, and 6 the most common. All cauliflower strains were race 4 and the leaf mustard strain was race 6. A dendrogram derived from the combined rep-PCR profiles showed that the Nepalese X. campestris pv. campestris strains clustered separately from other Xanthomonas spp. and pathovars. Race 1 strains clustered together and strains of races 4, 5, and 6 were each split into at least two clusters. The presence of different races and the genetic variability of the pathogen should be considered when resistant cultivars are bred and introduced into regions in Nepal to control black rot of brassicas

Pesticide Use in Vegetable Crops: Frequency, Intensity and Determinant Factors

This paper has examined pest management practices in four important vegetable crops, viz. chillies, cauliflower, brinjal and bhendi using farm level cross-sectional data. Average pesticide usage has been estimated at 5.13, 2.77, 4.64 and 3.71 kg active ingredient per hectare on chillies, cauliflower, brinjal and bhendi crops, respectively. On an average, cauliflower and brinjal are each given 15 applications, chillies is given 13 and bhendi is given 12 applications. The study has suggested that for reducing pesticide-use, farmers need to be educated about different nonchemical control methods and should be encouraged to adopt integrated pest management (IPM) practices.Agricultural and Food Policy,

PlantyOrganic: Design and results 2012

Increasingly strict legislation about fertilizer inputs and developing organic regulations are a strong stimulation to optimize the internal nutrient dynamics of organic arable farms. In the project “PlantyOrganic” , initialized by Biowad and realized at SPNA location Kollumerwaard, a challenging arable system is developed and tested: 100% internal nitrogen supply without input of nutrients from outside. In this report the design of the rotation and fertilizer scheme is presented and discussed, and the starting conditions in spring 2012 are documented. The NDICEA nitrogen model is used to explore the nitrogen dynamics. It is concluded that a 100% farm-own nitrogen supply can be achieved with good production levels. The 2012 results gave no reason to reconsider the rotation and fertilizer design, but since this was the first year of this experiment none of the crops had the precrop as foreseen in the design and the fertilizer used was only partly cut-and-carry fertilizer

Management of vegetable crop residues for reducing nitrate leaching losses in intensive vegetable rotations

Crop residues of field vegetables are often characterized by large amounts of biomass with a high N-content. Despite low soil temperatures during autumn, high rates of N mineralization and nitrification still occur causing important N-losses through leaching1. Crop residues pose a possible threat to maintaining water quality objectives, while at the same time being a vital link in closing the nutrient and organic matter cycle of soils. Appropriate and sustainable management is needed to obtain the full potential of crop residues. In this research some novel strategies for vegetable crop residue management are being investigated. The outcome of this work will help in defining the best practices in vegetable production in order to better meet the requirements set by the nitrate directive, whilst making best use of a valuable organic material. Vegetable crop residues constitute an important link in the soil nutrient and organic carbon cycle and aid in maintaining soil quality and fertility. However during autumn large amounts of N are released by vegetable crop residues causing important N-losses through leaching. Appropriate and sustainable management is needed to obtain the full potential of crop residues while meeting water quality objectives. In this research the potential of removal and valorisation of vegetable crop residues by means of ensilage or composting was evaluated

Multiplex quantitative PCR for single-reaction genetically modified (GM) plant detection and identification of false-positive GM plants linked to Cauliflower mosaic virus (CaMV) infection.

BACKGROUND:Most genetically modified (GM) plants contain a promoter, P35S, from the plant virus, Cauliflower mosaic virus (CaMV), and many have a terminator, TNOS, derived from the bacterium, Agrobacterium tumefaciens. Assays designed to detect GM plants often target the P35S and/or TNOS DNA sequences. However, because the P35S promoter is derived from CaMV, these detection assays can yield false-positives from non-GM plants infected by this naturally-occurring virus. RESULTS:Here we report the development of an assay designed to distinguish CaMV-infected plants from GM plants in a single multiplexed quantitative PCR (qPCR) reaction. Following initial testing and optimization via PCR and singleplex-to-multiplex qPCR on both plasmid and plant DNA, TaqMan qPCR probes with different fluorescence wavelengths were designed to target actin (a positive-control plant gene), P35S, P3 (a CaMV-specific gene), and TNOS. We tested the specificity of our quadruplex qPCR assay using different DNA extracts from organic watercress and both organic and GM canola, all with and without CaMV infection, and by using commercial and industrial samples. The limit of detection (LOD) of each target was determined to be 1% for actin, 0.001% for P35S, and 0.01% for both P3 and TNOS. CONCLUSIONS:This assay was able to distinguish CaMV-infected plants from GM plants in a single multiplexed qPCR reaction for all samples tested in this study, suggesting that this protocol is broadly applicable and readily transferrable to any interested parties with a qPCR platform

The Production of Cauliflower Microshoots using Curd Meristematic Tissues and Hypocotyl–derived Callus.

The capacity for microshoot production from cauliflower was investigated applying two different protocols. In the first, cauliflower curd meristematic tissue was used as a source of explants. The meristematic layer was shaved off and the clusters produced were homogenised using a commercial blender. In terms of its effect on the number and viability of microshoots, the use of 30 s blending duration treatment was found to be optimal between several treatments tested in the range 15 to 120 sec. Explants were cultivated in agitated S23 (MS (Murashige and Skoog, 1962) + 3 % sucrose) liquid media supplemented with different combinations of plant growth regulators. The use of 2 mg/L kinetin and 1 mg/L IBA gave the optimal results in terms of the number and viability of microshoots. The second protocol was designed to investigate the regeneration potential of hypocotyl explants of cauliflower via callus culture. The callus tissue was initiated from hypocotyl explants in callus induction medium (CIM), which consisted of S23 supplemented with 2,4-D at 1 mg/L and kinetin at 1.5 mg/L. The highest number of shoots was obtained after 28 days from sub-cultured hypocotyl derived callus on S23 basal media containing 0.5 mg/L of kinetin. This study demonstrated the ability of producing microshoots using various parts of cauliflower through both callus and without callus formation which can be useful in the later applications of cauliflower tissue culture such as the production of artificial seeds