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The tomato (Solanum lycopersicum L.) is one of the most popular and widely consumed vegetables in the world, being also the most common vegetable within the Mediterranean diet. The last few years have seen the appearance on the market of several types of agricultural plastic developed to alter the spectrum of radiation that enters the greenhouse, sometimes filtering it and, in other cases, intensifying certain wavelength bands. The objective of this study was to evaluate the production of tomato cultivated under different covers and to analyze the profitability of the yield, under each of them. A study was carried out in six tunnel greenhouses, with an area of 100 m² each, to evaluate the effect of different types of plastic roof, with different radiation properties. The yield of tomatoes was recorded and valued economically as a function of the mean prices of the Consejería de Agricultura de la Región de Murcia (CARM) (Department of Agriculture of the Region of Murcia) of the last years and one survey of the wholesale markets network (Mercas) and farmers, in order to know the weekly prices according to the caliber. The production costs of each of the alternatives were determined and the net present value of the yield and the annualized value were obtained. The highest annualized value was obtained with the UVA100%e cover (€24,856.04 per year), followed by UV90%e and PeTc (€18,931.49 and €16,205.53 per year, respectively). The LDe and Anti NIR covers provided the poorest results (€3,954.93 and €10,480.40 per year, respectively).
 

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In recent years, the use of photoselective shading nets to mitigate the harmful high radiation caused by the increase in temperatures is growing. The objective of this work was to study the positive effects - in terms of yield and profitability of photoselective shade nets in two types of pepper: Lamuyo (cultivars Alcudia and Pompeo) and California (cultivars Bendigo and Cayetano). The weekly yields, classified into different calibre, were analysed over two years, and for the analysis of economic profitability, the Equivalent Annual Value (EAV) was used with an analysis of sensitivity. The yields obtained with the pearl-colored net giving 30% shading were superior to open cultivation (no netting), in all the studied cultivars; in particular, Cayetano and Pompeo had 136 and 86% greater yields, respectively. This same trend was observed for the red-colored net giving 30% shading, with 88 and 74% increase in yield in Cayetano and Pompeo, respectively. In economic terms, the EAV was superior with the use of the pearl net, especially for the cultivars Alcudia and Cayetano - being €14,864 and €13,326 ha^-1 yr^-1, respectively. The yield and profitability were better for the crops grown under the pearl-colored photoselective net, especially for cultivars Alcudia and Cayetano. The sensitivity analysis showed that the probability of obtaining negative returns was higher in the absence of netting, while under the shade nets it was below 10%.

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Photoselective nets are used to protect horticultural plants from sunburn and prolong the cropping period in conditions of excess light. In this work, we studied the influence of four photoselective shading nets (Pearl 30, Red 30, Silver 30, Red 40), a standard black-colored net (Black 35), and a control (no cover) on the evolution of color during the ripening of two types of pepper, namely, Lamuyo and California. For this purpose, the evolution of the colors of the fruit was followed from the beginning of their formation until the harvest, and was correlated with the total radiation and the temperature. The plant material used were peppers of the California type -cultivars Bendigo and Cayetano- and of the Lamuyo type, cultivars Alcudia and Pompeo. The results showed that the rate of change of the pepper coloration depended on the net used in the greenhouse. The speed of the change in color from green to red was more dependent on the cultivar and the total radiation, as conditioned by the different photoselective nets, than on the type of pepper. The greatest differences were between the control (without a net) and the black net, the increase in the red color of the peppers being faster in the former. Radiation values below 75 W m^-2 or greater than 110 W m^-2 negatively affected the yield. The temperature below the net was not affected significantly by the type of net, and thus its effect on the different cultivars was similar.