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Padron-Mederos M.A.,Instituto Canario Of Investigaciones Agrarias Icia | La serna-Ramos I.E.,University of La Laguna
Plant Biosystems | Year: 2011

The pollen of Canary endemic genus Allagopappus Cass., which includes two species, was examined by light and scanning electron microscopy. Ten populations in all were studied and the following parameters were measured: polar axis (P), equatorial diameter (E), polar exine thickness (Ex1), length (L) and thickness (A) of the spines in the meridional optical section, exine thickness at the centre of the mesocolpium in the interapertural area (Ex2) and distance between spines (De) in the equatorial optical section. The data were processed statistically by the Simpson & Roe graphical test, ANOVA I test for population analysis, and Student's t test for species analysis. Pollen grains are trizonocolporate with shape generally oblate-spheroidal and also prolate-spheroidal, spheroidal or suboblate. Tectum is complete, perforate, with supratectal spines. The results show that the pollen of the two species is very similar regarding shape, apertures, and ornamentation. Nevertheless, the Student's t test shows that pollen from Allagopappus viscosissimus Bolle is larger and it has a thicker exine than that of Allagopappus dichotomus (L. f.) Cass. with a highly significant difference. Furthermore, the ANOVA test seems to point out differences for P, E, Ex1, and Ex2 between populations. © 2011 Società Botanica Italiana. Source


Rodriguez A.,University of La Laguna | Rodriguez C.,Instituto Canario Of Investigaciones Agrarias Icia
World Journal of Microbiology and Biotechnology | Year: 2014

Tomato greenhouses in the Canary Islands, Spain, were surveyed to estimate frequencies of resistance to benzimidazoles, dicarboximides, anilinopyrimidines and N-phenylcarbamates in Botrytis cinerea. Resistance to carbendazim, iprodione, pyrimethanil and diethofencarb was found in 74.2, 86.4, 28.8 and 31.8 % of isolates, respectively. Benzimidazole- and anilinopyrimide-resistant isolates were highly resistant, showing EC50 values above 500 μg/ml carbendazim and a mean EC50 value of 28.42 μg/ml pyrimethanil, respectively. By contrast, a low level of resistance was observed among dicarboximide-resistant isolates (mean EC50 value of 1.81 μg/ml iprodione). Phenotypes with double resistance to carbendazim and iprodione, and triple resistance to carbendazim, iprodione and pyrimethanil were the most common, occurring in 36.4 and 28.8 % of isolates. The surveyed greenhouses had never been treated with fenhexamid and Signum™ (pre-packed mixture of boscalid and pyraclostrobin), and baseline sensitivities of B. cinerea isolates to these fungicides were determined. The EC50 values were within the range of 0.009-0.795 μg/ml fenhexamid and of 0.014-0.48 μg/ml Signum. In addition, available formulations based on elicitors of plant defense response and biocontrol agents were evaluated against B. cinerea in tomato plants under semi-controlled greenhouse conditions, the yeast Candida sake CPA-1 being able to reduce gray mold significantly when it was applied on petiole wounds and the plants were inoculated 24 h later. Likewise, C. sake was effective against B. cinerea in harvested tomato fruits, yeast-treated tomatoes showed a 70.66 and 30.31 % reduction in the diameters of decay lesions compared with controls after 10 days of storage at 20 and 9 °C, respectively. © 2014 Springer Science+Business Media Dordrecht. Source


Sauco V.G.,Instituto Canario Of Investigaciones Agrarias Icia
Acta Horticulturae | Year: 2013

Despite globalization, most tropical fruits are still confined to their area of origin or nearby regions. The reasons for this confinement are complex but the lack of research into different horticultural practices, such as cultivar improvement, methods of propagation, nutrition and irrigation, pest and disease control, postharvest and marketing is always a common feature. The introduction of exotic fruits outside the normal cultural and dietary habits of the consumers also requires a lot of promotional effort in market development. This paper outlines the factors, which may be of major importance in creating a continued and sustainable demand for a new fruit in the international market. © 2013 ISHS. Source


Regalado C.M.,Instituto Canario Of Investigaciones Agrarias Icia | Ritter A.,University of La Laguna
Tree Physiology | Year: 2013

We investigate evapotranspiration, sap flow and top soil water content variations in a wax myrtle-tree heath ('fayal-brezal' in Spanish) cloud forest in the Garajonay National Park (La Gomera, Canary Islands) over a 1-year period. We provide transpiration estimates for one of the representative species, the shrubby needle-like Erica arborea L., present in this relict subtropical forest. An ad hoc tree up to the stand scaling method that combines the sap flow and auxiliary reference evapotranspiration data is illustrated, showing to be useful when sap flow in a limited number of trees has been monitored. Individual daily-based scaling curves of the Gompertz type were necessary to explain the observed sap flow variability in E. arborea during the 1-year period investigated (r2 ≥ 0.953 with mode of r2 = 0.9999). The mean daily sap flow of an E. arborea individual amounted to 8.37 ± 5.65 kg day-1 tree-1, with a maximum of 20.48 kg day -1 tree-1, yielding an annual total of 3052.89 kg tree-1. A comparison of the computed daily transpiration with the continuous micrometeorological time series monitored in the studied plot suggested that solar radiation was the main driving force of transpiration in E. arborea (cross correlation index = 0.94). Fog may also affect tree transpiration via its reduction of radiation and temperature, such that during foggy periods the mean daily water loss estimate of E. arborea was 5.35 ± 4.30 kg day-1 tree-1, which sharply contrasted with the 2.4-fold average transpiration values obtained for fog-free days, i.e., 12.81 ± 4.33 kg day-1 tree-1. The annual water balance rendered a 288 mm year-1 water input to the forest and evidenced the need for accurately quantifying the contribution of fog water dripping from the canopy. © 2013 The Author 2013. Source


Regalado C.M.,Instituto Canario Of Investigaciones Agrarias Icia | Ritter A.,University of La Laguna
Atmospheric Research | Year: 2016

We investigate the collection efficiency of different fog water catchers assemblies (mainly flat and cylindrical structures equipped with several screens of staggered filaments) by means of parametric equations which take into consideration both impaction and aerodynamic effects. We introduce different models that vary in complexity and range of applicability, and may be used to analyze the effect that geometry, number of screens, spacing and inclination of the filament strands have on the fog water yield of the collector. Increasing the number of impacting screens, nR, is shown to improve the collection efficiency up to an optimum for nR = 3-5; beyond nR > 5 impermeability to the airflow makes the fog catcher less efficient. Geometry of the collector is shown to be relatively important: unless wind direction varies widely, the rectangular flat design is preferred over the cylindrical one, because of its larger drag, i.e. increased aerodynamic efficiency, ηa. In fact ηa is shown to be limiting, such that values over ηa > 50% are difficult to attain. By contrast the impaction efficiency, ηimp, of fog water droplets onto multiple nR parallel screens of filaments may reach theoretical values of ηimp > 80%. Inclination of the impacting screens over the vertical may slightly reduce ηimp, but this may be compensated by a reduction in flow resistance, i.e. increased aerodynamic efficiency. © 2016 Elsevier B.V. Source

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