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Saffron is one of the most appreciated, traditional, and expensive spices in the world. The objective of our study was to evaluate the effect of cooling the nutrient solution on the production, and organoleptic and commercial qualities of saffron grown in soilless culture. The nutrient solution was cooled to 4 to 5 °C 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, crocin, and picrocrocin were analyzed spectrophotometrically according to the International Organization for Standardization [ISO/TS 3632-2 (2011) Normative]. Our results show that cooling of the nutritive solution increased flower production, the commercial phytochemical content, and organoleptic properties.

The response of root growth in containers has been studied in recent decades. The objective was to evaluate the effect of four types of containers on root and shoot growth. The containers were two shapes, round and square, and in some containers, internal vertical walls (IVWs) were placed that increased the internal container surface area with two substrates: perlite and coir fiber. Seedlings of cucumber, pepper, and tomato were transplanted. Two experiments were performed: vegetative growth and drought stress by partial decapitation and a period without fertigation. After decapitation, preexisting and new leaf area, dry biomass or the leaves, and stem were measured. The results revealed that the type of container had no effect, nor were there significant differences between substrates. The containers with IVWs exhibited an increase in biomass and the root surface. The total contact surface with the substrate of the four container types was closely related to the recorded plant growth. Thus, IVWs not only decrease mechanical problems of roots by preventing spiralling but also favor the production of biomass in vegetable plants and substantially increase the root, enabling the plants to manage water deficit and potentially improve posttransplant stress.

The effect of pH and silicon (Si) in the nutrient solution on the vegetative development of 2-year-old blueberry plants (Vaccinium corymbosum L. cv. Ventura) was studied. Two independent experiments were performed on coir fiber (CF) and sand as substrates. In experiment 1, Si was applied in the nutrient solution at a dose of 0.0, 0.3, 0.6, and 1.2 mm. In experiment 2, plants were treated with nutrient solution at pH 4.00, 4.75, 5.50, and 6.25, using two sources of acidification: nitric acid and citric acid. The parameters of plant growth, foliar surface, and stem biomass were measured. With the application of 1.2 mm Si to CF, plant height registered a significant increase of 8%, and shoot dry and fresh biomass increased by 21% and 25%, respectively. The results of experiment 1 indicated that the application of Si benefits the vegetative growth of blueberry plants in CF, but no effect was observed in the sand substrate. In the results of experiment 2, the pH level of 6.25 in CF decreased the dry weight of stems and leaves by 21% and 18%, respectively. A significant increase in the pH range of 4.00 to 5.50 was recorded in both the citric acid and nitric acid treatments, but these significant effects were not found in sand. Citric acid presented a similar behavior to nitric acid, which indicates that it can be a good source of acidification in organic and ecologically friendly crops.

The use of colored shade nets is a method to protect plants from direct solar radiation and optimize the light spectra they transmit. The purpose of this work was to evaluate the photosynthetically active radiation (PAR), the photosynthetically active integrated radiation (IPAR), temperature, relative humidity, growth, production, and fruit quality of Physalis ixocarpa variety Tecozautla, cultivated under nets generating 60% shade in the colors beige, blue, green, red, and black and under a treatment without netting (control group). Different variables were observed: climatic variables, such as radiation, temperature, and relative humidity; growth variables, such as plant height and stem diameter; production variables, such as number, weight, and caliber of the fruit; and quality variables of the fruit, such as pH and total soluble solids. The highest PAR, IPAR, and temperature and lowest relative humidity were obtained in the absence of netting. The white net resulted in the highest PAR and IPAR but no difference in temperature or relative humidity. In addition, an increase in the height, stem diameter, number of branches, and weight, number, and size of the fruit was observed. The white net resulted in the highest yield: 88% higher than in the control group. The pH of the fruit was significantly higher under the white netting, and no differences among the treatments in terms of the content of total soluble solids were found.

An intercrop is studied here as a new way of farming in soilless systems within a protected environment. To estimate the efficiency of intercropping in this cultivation system, an experiment was conducted to evaluate the effect of the electrical conductivity (EC) of the nutrient solution (2.0, 2.5, and 3.0 dS·m−1) on lettuce and tomato plants and on the agronomic and economic feasibility of the intercrop compared with monoculture. The results indicated that a moderate increase in EC from 2.0 to 3.0 dS·m−1 did not exert any important effect on tomato plant production or quality but did cause a decrease in lettuce yield in both the first and second crops. Intercropping was only feasible for lettuce when the tomato and lettuce plants were transplanted on the same day. The highest tomato (G class) and lettuce yields were achieved at an EC of 2.5 dS·m−1; this condition resulted in the highest intercrop profitability (0.53 €·m−2 more) when compared with tomato monoculture.

Greenhouse tomato production is shifting to meet emerging consumer needs. Increasing environmental concerns have pressured growers to supply high-quality vegetables using sustainable production methods. The utilization of adapting fertigation to production conditions and/or nutrient solutions of moderately high conductivity seems promising in providing high yields of superior quality while limiting the emission of nutrients to the environment in greenhouse tomato crops. A tomato crop was grown in soilless culture with various levels of electrical conductivity (EC), 2.2, 3.5, and 4.5 dS·m−1, adjusting the final nutrient concentration and maintaining nutritional balance. The effect of nutrient solutions with moderately high EC on fertigation parameters and the emission of nutrients to the environment, total crop productivity, distribution of fruit sizes, and dietary and organoleptic qualities were measured. Nutrient solutions of moderately high EC decreased total and commercial yield, with an average reduction from 5% to 19% and 3% to 22%, respectively. A considerable decrease in extra large and large fruits, with an average reduction from 69% to 42%, was also observed. Nonetheless, dietary-related metabolites were significantly increased at the highest EC values: lycopene (6.3%), ascorbic acid (8.8%), total phenolics content (8.3%), and total antioxidant activity (11.1%). EC values of 3.5 and 4.5 dS·m−1 are not widely used in commercial production but are frequently measured in drainage solutions in open hydroponic systems and discarded solutions in closed systems, mainly because of the use of poor-quality water and the accumulation of excess nutrients.

The effect of peracetic acid on the vase life and bud opening of cut flowers of Lisianthus was investigated. Eustoma grandiflorum is an attractive cut flower with a considerable length of vase life (usually weeks for freshly harvested stems). It is well known that the addition of sucrose into the vase solution increases significantly the longevity of cut flowers. Two different experiments of vase life were carried out. The first used cultivars of the Mariachi Series: Blue, Green, Blue Picotee, and Pink, whereas the second used Rosita White and Piccolo White 1. The control plants (T1) were supplied with tap water. Treatment 2 (T2) was similar to T1 with the addition of 3% sucrose. In the third (T3) and fourth (T4) treatments, sodium hypochlorite and a stabilized peracetic mixed system (PAA) were added, respectively. The number of flowers that opened from buds between cultivars was significantly different. With the addition of sucrose into the vase solution, a significant increase in longevity was recorded, which was also observed after the addition of both biocides to the respective treatments. This can be extended up to 15% by the addition of sucrose to the vase solution and up to 30% if PAA is incorporated into the vase solution. The results suggest that PAA can be a useful alternative to sodium hypochlorite for vase solutions because it is without the health drawbacks of trihalomethanes. The degradation of PAA is environmentally friendly, because it decomposes to form biodegradable acetic acid and eventually enters the environment as atomic oxygen.

Based on a new structure for plastic culture channels, a new system for soilless culture called New Growing Systems (NGS) has been developed. It is similar to the nutrient fi lm technique (NFT) but with several potential advantages. Each NGS growing channel has fi ve plastic layers and a large number of holes, there is a dripper every 0.5 m above the fi rst layer of plastic, and each dripper supplies the nutrient solution which fl ows from the second layer over the others to the end. Three separate greenhouse experiments with tomato, cucumber, and sweet pepper using NGS channels were conducted in Almeria (southeastern Spain). The oxygen content in the circulating nutrient solutions was determined at different points and different times along the channels of all crops. Depletion of oxygen content in the nutrient solution was lower than NFT channels. Oxygen content in NGS showed some advantages compared to NFT. Roots have to fi nd oxygen in their immedi- ate environment (Drew, 1983). Early studies about oxygen content in nutrient solution have shown that inadequate aeration may cause waterlogging in the roots of many plants; and that suffi cient forced aeration may be very expensive (Zeroni et al., 1983). It is known that oxygen concentration in the nutrient solu- tion of an important number of experiments is a limiting factor for plant growth (Adams, 2002; Morard et al., 2000; Zeroni et al., 1983). Gislerod and Kempton (1983) described varia- tions in oxygen content of the nutrient fi lm technique (NFT) solution during the daytime growth of cucumbers and tomatoes. Nutrient-fi lm technique crop production is a growing method, in which the plants have their roots in a shallow stream of recirculant- ing nutrient solution. This growing system can be found all around the world and has been in use commercially since the 1970s (Carrasco, 2004; Cooper, 1996). Based on a new structure for plastic culture channels, a private company invented and has been developing a new system in soilless culture over the last few years, it is called New Growing Systems (NGS ) and is similar to NFT but with several potential advantages. Since the 1990s NGS have been improved with commercial successful, between Spain, Italy and Mexico, the total commercial area using the NGS today is estimated to be about 100 ha. The present experiments studied the oxygen content of the new NGS. This was analyzed under commercial conditions and compared with the traditional NFT. cucumber ('Cuzco') and sweet pepper ('Mar- umba') were propagated in rockwool cubes and placed in the channels in February, July, and August respectively. Plant density was one plant per square meter for cucumber and two for tomato and sweet pepper. The nutrient solutions were similar to that used by Sonneveld and Straver (1994). Before the nutrient solution was recycled, it was poured into the catchment tank. The volume of solution in the catchment tank was maintained, a nutrient solution of the same composition and pH as was added to the tank at the beginning of the day. Temperatures were between 12 and 22 °C. The plastic channels were 22 m long and 2 m apart. The morphology, different layers and the holes between them of NGS channel are shown in Fig. 1. There was a slope 2%, and a dripper every 0.5 m above the plastic channels. Each dripper supplied the nutrient solution which fl owed from the second layer over the others to the end. Each experiment was carried out in 2500 m 2 . One plastic channel was the experimental unit and this was chosen at radom inside of greenghouse. Oxygen in the circulating nutri- ent solutions was determined by a WTW Oxi 340 oximeter. Samples of the nutrient solution were collected at six different points in the three experimental units, three from the fi nal drainage of different channels and the three drippers. The procedure use were according to (1983) using 2-mL glass syringes.