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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.

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Avocado ( Persea americana Mill) is rich in a variety of essential nutrients and phytochemicals; thus, consumption has drastically increased in the last 10 years. Avocado unlike other fruit is characterized by oil accumulation during growth and development and presents a unique carbohydrate pattern. There are few previous and current studies related to primary metabolism. The fruit is also quite unique since it contains large amounts of C 7 sugars (mannoheptulose and perseitol) acting as transportable and storage sugars and as potential regulators of fruit ripening. These C 7 sugars play a central role during fruit growth and development, but still confirmation is needed regarding the biosynthetic routes and the physiological function during growth and development of avocado fruit. Relatively recent transcriptome studies on avocado mesocarp during development and ripening have revealed that most of the oil is synthesized during early stages of development and that oil synthesis is halted when the fruit is harvested (pre-climacteric stage). Most of the oil is accumulated in the form of triacylglycerol (TAG) representing 60–70% in dry basis of the mesocarp tissue. During early stages of fruit development, high expression of transcripts related to fatty acid and TAG biosynthesis has been reported and downregulation of same genes in more advanced stages but without cessation of the process until harvest. The increased expression of fatty acid key genes and regulators such as PaWRI1 , PaACP4-2, and PapPK-β-1 has also been reported to be consistent with the total fatty acid increase and fatty acid composition during avocado fruit development. During postharvest, there is minimal change in the fatty acid composition of the fruit. Almost inexistent information regarding the role of organic acid and amino acid metabolism during growth, development, and ripening of avocado is available. Cell wall metabolism understanding in avocado, even though crucial in terms of fruit quality, still presents severe gaps regarding the interactions between cell wall remodeling, fruit development, and postharvest modifications.

Salinity is well known to reduce plant growth and yield by reducing water availability; it does so by interfering with both nutrient uptake and translocation. The objective was to determine the nitrate and potassium contents in xylem sap and the root-shoot transportation of both as a function of the salinity of the nutritional solution provided. We compared NO 3 -and K + contents and flux in xylem sap collected from cut stems of tomato seedlings, based on electric conductivity (EC) tests among five nutrition solutionsfor soilless crops ranging from medium to high salinity. The EC was 2.2, 3.5, 4.5, 6 and 12 dS m -1 . The concentration of nitrates and potassium in the xylem sap remained constant, while the external concentration in the rhizosphere varied greatly. Notwithstanding, the xylematic flux was strongly affected by the salinity of the nutritional solution: at maximum salinity, EC reached 3.5 dS m -1 ; at minimum, EC was 12 dS m -1 . For similar reasons, the longest NO 3 -and K + transportation distance between root and shoot was achieved when the EC read 3.5 dS m -1 , but was reduced by up to 80% when EC was 12 dS m -1 .

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2 Rocket (Eruca sativa Mill.) is a green leafy vegetable that is increasingly used as an ingredient in salad. The floating system is a way to grow this crop, at high density from sowing to harvest and easy to use in relation substrate culture, and it is well known water culture can be limited by hypoxia. Few studies have examined the use of peroxides or peracetic acid in nutrient solutions as a source of oxygenation. The aim of the study was to evaluate the rocket grown in substrates as compared to the floating system, with a stabilized mixture of peracetic acid in the nutrient solution. The experiment was carried out in and Talca (Chile) from October to November 2008. The treatments were substrate culture perlite and composted pine bark (1:1); floating system with trays filled with the same substrate and 0, 40 and 80 mg·L −1 of stabilized peracetic acid mix (PA). The fresh and dry weight of rocket leaves at harvest we evaluated. We recorded total nutrient solution uptake; the average dissolved oxygen; pH and electrical conductivity (EC). A randomized complete block design with four replicates was conducted using Tukey's multiple range test (P < 0.05). The results suggest from 40 to 80 mg·L −1 PA applied to the nutrient solution, increases the fresh and dry weight in the rocket crop grown by floating system and may compensate this limiting factor in the growth, if it was compared with higher oxygen available substrate culture.