José Pérez-Alonso

Greenhouse tomato production with electricity generation by roof-mounted flexible solar panels

The integration of renewable energy sources into greenhouse crop production in southeastern Spain could provide extra income for growers. Wind energy could be captured by small to medium-sized wind turbines, gas could be produced from biomass, and solar energy could be gathered by solar panels. The aim of this study was to examine the effect of flexible solar panels, mounted on top of a greenhouse for electricity production, on yield and fruit quality of tomatoes (Solanum lycopersycum L., cv Daniela). This study was undertaken in a commercial raspa y amagado greenhouse, typical of the Almeria region (Spain). Tomato plantlets were planted at a density of 0.75 plants m-2. The flexible solar panels were mounted on two parts of the roof in different arrangements (T1 and T2), each blacking out 9.8 % of its surface area. A control area (T0 arrangement) was fitted with no panels. No difference was found in terms of total or marketable production under these three arrangements, although fruit mean mass and maximum diameter of T0 were significantly greater than T1 and T2. Fruit in T0 matured earlier with more intense color compared with those in T1 and T2. However, these differences had no effect on price as the tomatoes produced under three conditions fell into the same commercial class (G class; diameter 67-81 mm). Solar panels covering 9.8 % roof area of the greenhouse did not affect yield and price of tomatoes despite of their negative effect on fruit size and color.

Accidents in the greenhouse-construction industry of SE Spain

This work analyses the labour accidents in the greenhouse-construction industry of SE Spain for the period 1999-2007 through a sample of 180 accident reports. The accidents were characterised by studying 5 variables in order to know the day of the week in which the accident occurred, the hour of the day of the accident, type of accident, the region of Spain in which the accident happened, and the resulting injury. The data characterising the accidents were submitted to a descriptive multiple-correspondence analysis. The incidence of accidents in the greenhouse-construction industry presented a high mean value of 15133.7 per 100,000 workers per year. The days with the greatest incidence of accidents were Thursday and Monday, while the period of greatest number of accidents occurred in the first 4h of the workday. No significant correspondence was found between the day of the week, the hour of the day, or any of the other 3 variables studied. The types of accidents with most frequency were: cuts, punctures, contact with hard or rough material, overexertion, and falls from one level to another. The most affected parts of the anatomy were the eyes, thorax, back, sides, lower legs, and feet. The most common types of injury were bone fractures, twists and sprains, distended muscles, contusions, and being crushed. The study calls attention to the high number of accidents at work, which needs to be corrected by fulfilment of safety regulations at work, on the part of the company. Finally, recommendations are made to correct this situation of high number of accidents at work.

Musculoskeletal disorders: OWAS review

The prevention of musculoskeletal disorders (MSD) is very important in the world. Governments and companies are the most interested. The objective of the present work is to review the literature on the applications of the OWAS method in the diverse sectors or fields of knowledge and countries from its publication to March 2017. The use of OWAS method has been classified by categories of knowledge, by country and by year. The search was made by selecting only the main collection of the Web of Science. This was selected by the option “Advanced search” using the term OWAS (ts=OWAS) for the time period of 1900 to 2017. A total of 166 results were found, consisting of conference papers and articles in scientific journals. In conclusion, the OWAS has been applied mainly in two sectors: “Manufacturing industries” and “Healthcare and Social assistance activities”. This method needs to be complemented with other indirect or direct methods. Also, whenever the OWAS has been used, whether individually or together with other methods, musculoskeletal disorders risks have been detected, this perhaps being an indicator to review the evaluation parameters because overestimating the risk.

Volume application rate adapted to the canopy size in greenhouse tomato crops

The application rate of plant-protection products is indicated as a concentration or amount of product per area. Greenhouse crops grow swiftly, and an application rate based on a fi xed amount of product per hectare can result either in large losses and overdoses when the plants are small or to be insuffi cient when the plants are fully developed. To solve these problems, the application rates of plant-protection products need to be adapted to the plant mass present in the greenhouse when the spray is applied. Two models were developed to estimate the leaf area based on easily measured geometric data of the vegetation in a greenhouse tomato crop. The model based on the PRV (Plant Row Volume) had that best results. The calculation of the vol- ume application rate from the PRV has resulted in a reduction of more than 30 % of the quantity of plant protection product sprayed, without decreasing yield. The PRV of a greenhouse tomato (Lycopersicon esculentum Mill.) is an easily measured parameter that enables the estimation of the leaf area index and the use of application strategies adapted to the changes in the plant canopy, saving major amounts of plant protection product used, compared to the conventional system.

Distributed network for measuring climatic parameters in heterogeneous environments: Application in a greenhouse

Abstract In Mediterranean countries of Southern Europe, the climatic conditions are usually favourable to cultivate greenhouse vegetables but not always for workers. The aim of this study was to design a network of weather stations capable of gathering data of environmental parameters related to the wellbeing of workers in greenhouses in south-eastern Spain. The unevenness of the thermal environment was studied both vertically as well as horizontally following guideline ISO 7726. The results indicate that the greenhouse should be considered a heterogeneous environment, implying that, for an evaluation of the environmental conditions related to thermal stress of the workers inside the greenhouse, measurements should be taken at different points within the greenhouse at three heights (ankle, abdomen, and head).

On air temperature distribution and ISO 7726-defined heterogeneity inside a typical greenhouse in Almería

Abstract Studies about the air temperature inside greenhouses are usually focused on the crop growth. However, the thermal environment inside greenhouses can affect the safety of the workers and also their productivity. This work focuses on the study of air temperature conditions with respect to workers following the requirements and methods gathered in ISO 7726, which indicates that measurements should be taken at different points in both, horizontal and vertical directions in order to study heterogeneous thermal environments. For the present work, data were gathered by the Wireless Sensor Network (WSN) designed in our previous work, hereby extended by an experimental campaign carried out during a complete year in a typical greenhouse in Almeriia. The aim is performing a long-term study of air temperature inside a greenhouse as well as the assessment of air temperature heterogeneity. The results, which allow characterizing air temperature inside the greenhouse, prove the existence of patterns of heterogeneity as a function of the incidence of sunlight and time of day. During the analysed period, air temperature heterogeneity is mainly present in the central hours of the day and it is higher in the horizontal dimension rather than vertically. In addition, it has been observed that the vast majority of homogeneous days correlate with cloudy days. Finally, based on the results obtained some recommendations are presented for assessing the thermal environment of greenhouses.

The Guatemalan Construction Industry: Approach of Knowledge Regarding Work Risks Prevention

In the present work, the results are presented for the characterization of work risk prevention in the Guatemalan construction industry. This characterization has been carried out using a simple random sampling technique, employing a questionnaire that was structured into 3 groups of variables: 1. General company data; 2. Prevention and management activities regarding health and safety in the company and on the worksite; and 3. Health and safety in the contractor companies. Following the sampling phase, the data were introduced in a database format, and a preliminary analysis was performed on the studied variables, followed by a descriptive analysis and a multiple correspondence analysis. The main findings of the study emphasize that companies in the Guatemalan construction sector are characterized as dedicating most of their activity (52.0%) indistinctly between civil engineering work, building construction and other specialized construction, mainly working as contractors (47.5%). These are “medium-sized” companies, employing an average of 81.1 on-site workers, having an average of 6.8 on-site work crews, and grossing an average turnover of 1.29 million euros annually. Likewise, it found that the larger construction companies adopt better prevention and management measures for worksite health and safety the larger companies are correlated with a high awareness of experiencing worksite accidents, while medium-sized companies have medium-level awareness. Companies with fewer workers manage workplace risk prevention worse, with low accident risk awareness. This correlation between these indicative variables of company size and workplace risk management and prevention is clearly reflected in the four company “clusters” that have been identified as having homogenous characteristics using the multiple correspondence analysis technique. Companies in the Guatemalan construction sector should make a greater effort to improve manager and worker training regarding workplace risk prevention to increase the effectiveness of company prevention management.