Miguel Urrestarazu

Vegetable Waste Compost as Substrate for Melon

Abstract The suitability of compost from horticultural residues as a growing medium in vegetable crop production was compared with the popular rock wool and coconut coir waste substrate. Physical and physio-chemical properties were initially characterized to adjust the management of this substrate for horticultural purposes. Leaching experiments were carried out with acid solution and standard nutrient solution. Two experiments were conducted to compare this compost with rock wool and coconut coir waste in terms of yield and fruit quality of a melon crop. The compost was found to initially have high salt content and a high pH. The results suggested that compost seems to be an acceptable growing medium for soilless vegetable production, provided that it is leached prior to use. Once it is leached, the compost is an acceptable substitute for rock wool and coconut coir waste.

Effect of Substrate Reutilization on Yield and Properties of Melon and Tomato Crops

ABSTRACT Certain ecologically-friendly substrates have recently been shown to be perfectly viable alternatives to other more traditional ones such as rockwool, perlite, or some hydroponic systems. However, in order to be competitive for vegetable production in the Mediterranean region, substrates must be used for at least one year. The present study assessed random samples of two commercial substrates, almond shell and compost from greenhouse vegetable residue. The substrates were evaluated as growing media for long-term soilless production. Three experiments were conducted to evaluate the effects of reusing these substrates, comparing them with rockwool in terms of yield and fruit quality characteristics of melon and tomato. The physical, physico-chemical, and chemical properties studied differed significantly on reutilizing these materials. However, these differences did not prove to be limiting factors when fertigation parameters applied were adjusted according to substrate properties. The results suggest that compost and commercial almond shells seem to be acceptable growing media after at least 265 and 530 days of reutilization, respectively.

Effects of Heating Nutrient Solution on Water and Mineral Uptake and Early Yield of Two Cucurbits under Soilless Culture

ABSTRACT Root temperature may affect the production of greenhouse vegetables under soilless culture. Four independent experiments were carried out over two consecutive crop cycles using two different substrates: rockwool and coconut coir waste. Three heating treatments were applied: non heating (T0), nutrient solution at 12–16°C (T1), and at 18–22°C (T2). The experiments were carried out in greenhouses in Almería (SE Spain) on cucumber and melon. Mean substrate and air temperature were not affected by the treatments. Under conditions of nutrient solution heating EC and percentage of drainage volume decreased, while water and mineral nutrient absorption increased. However, results showed great differences between both crops and substrates. A significant decrease in nitrate and phosphate emission from the substrates was also recorded, especially in rockwool substrate. Few effects were observed concerning yield and fruit quality parameters, but in rockwool-grown melon early yield was enhanced. It follows that nutrient solution heating is a low-cost and environmentally friendly method of increasing early melon yield.

Nitrate accumulation reduction using chloride in the nutrient solution on lettuce growing by NFT in semiarid climate conditions

Abstract Nitrate accumulation in vegetable represents a serious threat to mans health. Different methods have been reported to reduce the nitrate accumulation in lettuce and other leafy vegetables with or without variation in the yield. The aim of this experiment was to show the different behavior of some cultivars of lettuce using the replacement of N‐NO3 for chloride in the nutrient solution during last week before harvest. The trial was carried out with three lettuce cultivars: Domino, Elvira, and Daguan and took place in southern Spain (Almeria) under greenhouse by NFT. The results indicated a correct method to decrease nitrate content in leafy vegetables and perhaps sulphate could be an anion to study their effect in this way.

Xylem sap extraction: A method

Abstract Xylem sap extraction from decapitated plants by negative pressure will be discussed in this paper. This method of extraction, in which transpiration is simulated by a negative pressure, uses as a quantitative reference generated by non‐decapitated plants. For this method, several horticultural plant have been used with the main nutritive elements in the sap analyzed by ionic chromatography.

A daily rhythmic model for ph and volume from xylem sap of tomato plants

Abstract Ten‐day‐old tomato plants (Lycopersicon esculentum Mill. cv. Rambo) were transplanted in a NFT special system. The experiment was repeated three consecutive times. Each experiment consists of three replicates. The experiments were carried out first with 30‐day‐old plants and subsequently with plants which were 45‐days‐old. The sap flux rates (V) vary considerably during the day at both harvest dates and there was has highly significant correlation (p>0.999) with the chronophysiological rhythm (Halberg, 1969) which has the highest rates in the day and the lowest rates at night. The pH rhythm, which shows an opposite behavior of the sap flux rate, is related to organic anion equivalents (C‐A). A markedly difference in the behavior of C‐A values occurred at both harvest dates. The model presented in this paper may provide a framework for the explanation of short and long term V and pH fluctuation of xylem sap. The changes in the pH of the xylem sap are probably normally buffered, but may have the po...

Infrared thermography used to diagnose the effects of salinity in a soilless culture

Thermography is a tool used in many scientific disciplines, including agriculture. This paper describes the application of thermography to rapidly diagnosing salinity stress with a high degree of temperature resolution in potted ornamental crops. Syngonium podophyllum and Philodendron erubescens were transplanted to pots in a greenhouse in Almeria (Spain). Salinity treatments were 1, 2, 6 or 12 dS m−1 of electric conductivity in a nutrient solution. The comparison of thermography in relation to other assessment methods to measure salinity stress was studied. The results suggest that thermography can be an early useful method to diagnose saline stress in potted plants.

EFFECTS OF SALINITY AND THE INTERACTION BETWEEN THYMUS VULGARIS AND LAVANDULA ANGUSTIFOLIA ON GROWTH, ETHYLENE PRODUCTION AND ESSENTIAL OIL CONTENTS

This study evaluated the effects of salinity on thyme (Thymus vulgaris) and lavender (Lavandula angustifolia) plants grown alone and in combination with each other. After transplanting, two-month-old plants received nutrient solutions supplemented with 0, 50, and 100 mM sodium chloride (NaCl) for 21 d. Thyme and lavender grown alone were each more tolerant to salt stress than thyme and lavender grown together. In the 100 mM NaCl treatment, all lavender plants grown with thyme died. In thyme, the carbon (C) and nitrogen (N) contents of the roots increased. Ethylene production in thyme was stimulated by salinity only in plants that interacted with lavender. However, in lavender, ethylene production was not influenced by the presence of thyme. The production of essential oils (EOs) was increased by salinity in thyme plants, whereas the EO production of lavender plants depended on the presence of thyme.

Modeling electrical conductivity management in a recirculating nutrient solution under semi‐arid conditions

Abstract Our objective was to find an experimental and theoretical relationship between the electrical conductivity (EC) of nutrient solutions applied in open and closed systems for hydroponically‐grown plants in the semi‐arid regions of southern Spain. The experiments took place in a plastic greenhouse and were conducted from 1995 to 1998. In the first two years, beans and cherry tomatoes were grown in the autumn and spring, respectively, and in the last year, cucumber was grown in the autumn and spring. Crops were grown in soilless culture using perlite bags. The treatments were as follows: (i) no re‐use of the drainage nutrient solution, i.e., an open system, and (ii) re‐use of 100% of the drainage nutrient solutions, i.e., a closed system. In our region, irrigation water EC varies from 1.2 to 0.6. In the closed system, we noted an increase in the salinity of the nutrient solution and have suggested different methods to avoid salinity in the closed system.

The Effect of Amendment of Vegetable Waste Compost Used as Substrate in Soilless Culture on Yield and Quality of Melon Crops

One of the main environmental impacts of forced systems in horticulture — such as plastic covered and soilless culture — is the generation of organic plant residues and substrate waste. Many people are keen on research and development of ecologically friendly substrates. Thus, leaching experiments have been carried out with distilled water to determine whether compost — from horticultural greenhouse crop waste — can be used as growing media in vegetable crop production. The compost was examined and compared to other substrate alternatives like coconut coir waste. Two experiments were conducted in order to compare the two composts with coconut coir waste in terms of yield and fruit quality of melon crops (Cucumis melo). Electrical conductivity decreased sharply with leaching and eventually reached acceptable levels despite the high initial value of this parameter in the composts. This drop in electrical conductivity was parallel to that experienced in the contents of soluble mineral elements, with mainly high levels in SO42−, K+, Cl−, Mg2+, Ca2+ and Na+- concentrations. Most of the soluble mineral elements in compost were removed applying six times the amount of water. The comparison between two environmentally sound substrates, show that compost seems to be an acceptable ecological growing medium and similar to commercial coconut coir in soilless culture, it does not affect yield and quality of melon crops.