Abstract
Abstract The spatial behavior of the environmental variables involved in rose production is one of the factors of greatest current interest in the Colombian ornamental sector. The aim of this work consisted in the evaluation of a passive greenhouse through an experimental approach that included the capture and recording of data through a grid of 40 sensors homogeneously distributed inside the greenhouse. The data processing was carried out through the application of geostatistical techniques that allowed to obtain contour plots for 5 levels of radiation intensity. The results of the exploratory analysis showed that the behavior of temperature, relative humidity and vapour pressure deficit are not the most suitable for rose production, mainly for the conditions of the night period where the temperature exhibited values below 12.5 °C, the relative humidity was above 90% and the vapour pressure deficit was below 0.1 kPa. On the other hand in the structural analysis the circular model of theoretical semivariogram was the one that better degree of adjustment presented in comparison with the experimental data finding that a strong spatial dependency exists for the studied variables, the prediction of the not sampled points was made by means of the method of ordinary kriging finding that horizontal gradients of temperature and relative humidity exist inside the greenhouse that increases in magnitude according to the level of radiation arriving to reach values of 6.1 °C and 30.4%.
Highlights
The rose is a semi-climbing woody plant that produces flowers
For rose production under greenhouse the following microclimate conditions are recommended as being optimal for production, the temperature value should be between 18 and 25 °C for the day period (Kinfe et al, 2014) and for the night period between 14 and 18 °C (Reid, 2008), on the other hand it is appropriate that the relative humidity conditions are above 70% during the day and maximum 85% at night (Torre and Fjeld, 2001), likewise the value of the vapour pressure deficit should be between 0.4 and 1.2 kPa for the day and between 0.2 and 0.4 kPa for the night (Konopacki et al, 2018)
For the external solar radiation recorded during the measurement period, the quartiles were calculated excluding the solar radiation recorded during the night time as it is equal to zero, in total the data were grouped in 5 levels of radiation (Table 1). These are upper limits of the radiation level at which the data of the climate variables under study were grouped for subsequent analysis using geostatistical methods
Summary
The rose is a semi-climbing woody plant that produces flowers. It belongs to the Rosaceae family and is considered one of the four most important cut flowers in the world. Colombia is the second largest exporter of flowers after the Netherlands, its share of the international market is 16% of the world total. According to statistics from the Ministry of Agriculture and Rural Development (MADR) the main destination country for Colombian flowers is the United States with 78.1%. The area of cultivation under glass of the sector for the year 2018 was 8,433 hectares where a total of 239.497 tons of stems were produced for export generating foreign exchange earnings to the country of 1,403 million dollars, where the rose participated with a 23.8% which is equivalent to 333.8 million dollars (MADR, 2019). The Colombian ornamental sector has been established since its origins in a productive system under cover where passive greenhouses with natural ventilation predominate (Villagrán and Bojacá, 2019a, 2019c)
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