Scientific Journals of INIA (Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria)
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Effects of two commercial feeds with high and low crude protein content on the performance of white shrimp Litopenaeus vannamei raised in an integrated biofloc system with the seaweed Gracilaria birdiae
Get PDF A trial was conducted for 42 days to evaluate the effects of two commercial feeds with high and low crude protein content on the performance of white shrimp Litopenaeus vannamei cultivated in an integrated biofloc system with the seaweed Gracilaria birdiae. The experiment had a 2 × 2 factorial design (a biofloc monoculture or an integrated system with 32% (low) or 40% (high) crude protein content) with the following treatments: IS32 (an integrated system using low protein commercial feed); IS40 (an integrated system using high protein commercial feed); M32 (a monoculture system using low protein commercial feed); and M40 (a monoculture system using high protein commercial feed), all in triplicate. Shrimp individuals (0.23 ± 0.04 g) were stocked at a density of 500 shrimp/m3 and no water exchange was carried out during the experimental period. No significant influence (p > 0.05) was found to be caused by the integrated system or the crude protein levels on water quality. However, a significant influence (p < 0.05) was found for final weight (3.21–4.12 g), weight gain (2.97–3.89 g), yield (1.39–1.96 kg/m3) and feed conversion ratio (1.47–1.74). Growth was similar in IS32, M40 and IS40, indicating that crude protein levels can be reduced with no adverse effect on shrimp performance variables in integrated biofloc systems with G. birdiae
Valuation of agrifood SMEs. Lessons to be learnt from the stock market
Get PDFThe European agrifood industry is mostly characterized by small and medium enterprises (SMEs); as in 2013, SMEs represented 99.13% of the total number of companies. The valuation of SMEs not listed in any stock market is a complex task since there is not enough information on comparable transactions. When applying discounted cash flow (DCF) models to value private agrifood companies, the capital structure and the cost of equity are two key parameters to be determined. The implications of these parameters in the value of the enterprise are not clear inasmuch as it is not possible to carry out a contrast due, precisely, to the lack of comparables. The main goal of this study is to determine the biases that those two parameters can introduce into the valuation process of an agrifood company. We have used the stock market as a framework wherein to apply a simple fundamental model to the companies of the European food industry in order to obtain three valuation multiples. By means of two bootstrap approaches, the bias induced in the multiples has been assessed for every year from 2002-2013. Results show that the use of the return on equity as cost of equity tends to undervaluation; the use of capital asset pricing model (CAPM) tends to a slight overvaluation, whereas using the total beta induces an undervaluation bias. Moreover, the capital structure shows little influence on the valuation multiples. The conclusions drawn from this paper can be useful for managers and shareholders of privately-held agrifood companies
Begomoviruses infecting common beans (Phaseolus vulgaris L.) in production areas in Cuba
Get PDFViral diseases caused by begomoviruses are economically important for their depressing impact on common bean production in Cuba. Mayabeque is a Cuban province where this crop is significantly grown and affectations by Bean golden yellow mosaic virus (BGYMV) have been detected in the last 30 years. Integrated pest management (IPM) programs in this crop have allowed controlling the disease for a long time. However, in prospections of the last years, an increase of the incidence of various yellowing symptoms typical of begomoviruses has been observed in common bean production areas. DNA was extracted from leaf samples taken from symptomatic plants. Non-radioactive nucleic acid hybridization and a specific PCR assay were used to detect BGYMV, Common bean severe mosaic virus, Common bean mottle virus, and Tobacco leaf curl Cuba virus. Of the 218 bean plants sampled, 89.5 % was positive to BGYMV; the presence of the rest of the begomovirus species was between 3 and 4% (3.08% of CBMoV, 3.08% of TbLCCuV and 4.32% of CBSMV). The viral DNA from some samples was analyzed by rolling circle amplification (RCA), by restriction fragment length polymorphism analysis using restriction enzymes, and by cloning and sequencing of the viral components. The DNA sequences from BGYMV isolates showed 98% of identity with the isolates reported in Cuba in 2003. The infection by Tobacco leaf curl Cuba virus (TbLCCuV) was confirmed also in fields in the Cuban western region. This is the first work where the DNA-B of TbLCCuV is identified. These studies will help to strengthen phytosanitary surveillance and management programs implemented in the country to control the whitefly-begomovirus complex in this economically important crop
Short communication: Identification of cultivated and wild Vaccinium species grown in Portugal
Get PDFVaccinium crops offer a variety of benefits for human health due their high levels of antioxidants. Genetic diversity between two Vaccinium species (sixteen cultivars of Vaccinium corymbosum and three wild populations of Vaccinium myrtillus) were evaluated using Inter Simple Sequence Repeat (ISSR) markers. In V. corymbosum 74 polymorphic markers corresponding to 83.2% of polymorphism were obtained while in V. myrtillus only four polymorphic markers corresponding to 83.2% and 10.6% of polymorphism were observed. The dendrogram obtained showed a clear division into two distinct groups corresponding to the two analyzed species. V. corymbosum group is divided in different sub-clusters based on cultivars pedigree relationships. Twenty-eight specific bands were detected in total; 6 for V. corymbosum and 22 for V. myrtillus. Results allowed the selection of five primers due it potential to detect specific bands in the two species. These markers could be useful for identifying species and cultivars and consequently help in the management of germplasm collections and in breeding programs
Deficit irrigation in commercial mandarin trees: water relations, yield and quality responses at harvest and after cold storage
Get PDFTwo experiments were conducted on a commercial farm of late ‘Fortune’ mandarin trees in order to know the response of regulated deficit irrigation (RDI), mainly applied during the most harmful ripening stages, on plant water relations, yield and fruit quality at harvest and after cold storage at different temperatures. Control trees were irrigated to satisfy maximum crop evapotranspiration, while RDI-1 and RDI- 2 represented a 20% and 40% reduction, respectively, in the water applied. Total yield and fruit quality at harvest were not significantly affected by either treatment. Late stage II of fruit growth was the most sensitive period to water stress, while deficit irrigation applied during flowering and stage I of fruit growth resulted in a significantly higher number of fruits per tree and an improvement in irrigation water productivity compared with the Control treatment. In both experiments, skin chroma decreased during cold storage, at the same time as titratable acidity fell. Fruit quality (titratable acidity, skin C* and ascorbic and glutamic acids) were more affected by cold storage than by differences between the RDI treatments. The use of trunk diameter fluctuation was useful for restoring the RDI irrigation to levels of the Control at the end of early stage II. From a quality point of view, any difference between treatments found at harvest tended to diminish during the subsequent shelf-life after cold storage. Quality traits (titratable acidity, ascorbic and glutamic acid) could be used as chilling biomarkers
A sensitive real-time RT-PCR reveals a high incidence of Southern tomato virus (STV) in Spanish tomato crops
Get PDFSouthern tomato virus (STV) is a double-stranded RNA (dsRNA) virus belonging to genus Amalgavirus (family Amalgamaviridae). STV has been detected in tomato plants showing different symptoms although it has not been demonstrated that STV is the causal agent. To study the STV incidence and its pathogenic role, a sensitive and quantitative real-time reverse transcription-polymerase chain reaction assay (RT-qPCR) was developed. The standard curve performed with viral RNA transcripts allowed a wide dynamic range for STV quantitation from 104 to 1011 copies/ng of total RNA. STV detection by RT-qPCR was 102-fold more sensitive than conventional RT-PCR or RT-LAMP and 104-fold more sensitive than molecular hybridization. STV was detected in different tomato plant tissues, as well as in the coat and the embryo of individual seeds. Also, viral concentration remained constant over time in leaf tissues of STV-infected tomato plants. Surveys on different tomato fields from Spain revealed that STV was widespread. In addition, the virus was detected in almost every tomato variety and nursery analyzed. STV-infected tomato plants did not show any disease-related symptom suggesting that the virus was not directly the causal agent of any tomato disease. However, there is no information about the STV effect in mixed infections or in abiotic stressed conditions and further studies must be performed to clarify it. The RT-qPCR assay developed in this work could be implemented on sanitation programs in order to limit the virus spread and could be used to study the effect of STV in mix infections or abiotic stressed conditions
Pathogenic and biological characterization of Phytophthora capsici isolates from zucchini and pepper in Southeast Spain
Get PDFIn this work, isolates from pepper and zucchini were tested for pathogenicity on crops commonly cultivated in Mediterranean greenhouses. Also, morphological and growing features and mating types have been studied to find any differences linked with the plant origin and pathogenicity of each isolate. Three isolates were highly pathogenic on all cucurbitaceous and solanaceous hosts tested and caused root rot and wilting. Eggplant and pepper were moderately susceptible, while zucchini, tomato and cucumber were highly susceptible. No root rot symptoms occurred on the fabaceous plants inoculated with Phytophthora capsici, including bean and pea. Moreover, the pathogen was never reisolated from the roots of fabaceous plants. Other isolate of P. capsici was less pathogenic on cucurbitaceous and solanaceous crops, causing only slight root damages. None of the isolates tested produced chlamydospores, and all belonged to A1 mating type. These findings suggest that beans or peas may be a feasible alternative crop for those Mediterranean greenhouses with a history of root rot due to P. capsici
Optimum combination of soil amendments under drip irrigation with different water sources in coastal areas of East China
Get PDFThe effects of drip irrigation (DI) with fresh water (FW) and brackish water (BW) on saline-alkali soil improvement were compared under treatments of five amendment combinations. The experiment was designed using the orthogonal test method and performed using an indoor DI system. Soil electrical conductivity (EC), pH, sodium adsorption ratio and soil nutrients were analyzed after DI both before evaporation and after one month of evaporation. The results showed that after one month of evaporation, soil EC increased by an average of 97.26% and 27.76% for the FW and BW treatments, respectively. Furthermore, it was shown that soil nutrients increased greatly under the BW treatment and that cow dung proved to be a leading agent influencing soil nutrients except available soil potassium (p<0.05). Consequently, the optimum combination of soil amendments was determined as 0.03 m3/m2 of straw, 3 kg/m2 of phosphogypsum, 0.04 m3/m2 of cow dung, 0.6 kg/m2 of humic acid and 0.18 kg/m2 of microbial fertilizer under the BW treatment
