Técnicas de cultivo sin suelo y fertirrigación en el cultivo de azafrán

Abstract

Saffron (Crocus sativus L.) is an ancient crop since the Bronze Age, associated with the history and sociocultural values of mankind. One of the most expensive spices used in the food industry, it has been used for centuries to treat diseases. It contains several chemical compounds of great interest in food and pharmaceuticals, such as crocin, picrocrocin and safranal, to which these beneficial medicinal properties are attributed. In recent years, the demand for saffron has increased and there have been few technological advances to improve its production and commercial quality, which is determined by the specifications recommended by the International Organisation for Standardisation (ISO/TS 3632). The overall objective is to improve the production and quality of saffron through sustainable techniques in soilless cultivation. In order to achieve this objective, three experiments were carried out. Experiment 1. The effect of cooling the nutrient solution on the production, and organoleptic and commercial qualities of saffron grown in soilless culture was evaluated. The experiment was carried out using a four-block design with twelve plants per treatment. The corms were placed in a controlled culture chamber located at the University of Almeria, after a previous incubation for 55 days at 25 ºC. The nutrient solution was cooled to 4 to 5 ºC whereas the control treatment was the fertigation supplied at ambient temperature. Corms were placed in a controlled cultivation chamber. The number of flowers per corms, and the weight and length of stigmas were measured. The amounts of safranal, crocins, and picrocrocins were analyzed spectrophotometrically according to the International Organization for Standardization [ISO/TS 3632-2 (2011) Normative]. The results showed that cooling of the nutritive solution increased flower production, the commercial bioactive compounds content, and the organoleptic properties. Experiment 2. The effect of electrical conductivities (EC) of the nutrient solution on the production and commercial qualities of saffron in a soilless culture system was evaluated. The growing conditions and the parameters measured were similar to that obtained in the experiment 1. The treatments with standard macroand micronutrient contents were EC supplied at 1.5, 2.0, 2.5, 3.0 and 3.5 dS m-1 . The best results in fertigation uptake, vegetative growth and marketable production were obtained at EC 2.0 to 2.5 dS m-1 , while the best bioactive compounds concentrations and marketable category were recorded between EC 2.5 to 3.0 dS m-1 . Experiment 3. The effects of three different light spectra were evaluated using 18 W commercial LED illuminants, with an average intensity of 5.95 lamps. m-2 and using two illuminants with specific spectra for horticulture (T1 and T2), T2 being recommended for flowering induction. The experiment was carried out with saffron corms in a controlled plant growth chamber. The saffron corms were subjected to different treatments with a design of 4 blocks and fifteen plants per treatment, all at a density of 5.95 lamps m2 . Illuminance (Lux) and photosynthetic photon (FFF, µmol m-2 s -1 ) values of the LED lamps used were measured. The parameters evaluated were similar to those in experiment 1. No statistically significant differences were found between the different treatments for production and vegetative biomass. The best treatment in terms of production of bioactive compounds content related to quality was the sunlight-equivalent spectrum lamps (T1), although it was obtained the same quality category as that of the control treatment