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To exploit the full potential of plants, it is essential to provide an adequate water balance during critical growth stages. With knowledge of the substrate’s matric potential, it is possible to realistically measure the amount of water available to the plant. The objective of this research is to study the effect of the matric potential of the substrate on the growth of beans, lettuce, sweet peppers, watermelon, and cauliflower plants. The research goal was to evaluate the effect of the matric potential on the main fertigation parameters of horticultural plants. The plants were cultivated at the University of Almería (Spain) in a controlled chamber in a pot with 250 mL of coconut fiber substrate from block propagation. For treatments T15, T30, T45, and T60, new irrigation was applied when easily available water (EAW) depletion levels of 15, 30, 45, and 60% were reached, respectively. The efficiency of the use of water (WUE), nitrate (NUE), and potassium (KUE) was measured. From T15 to T60, a significant effect was found for the absorption of water, nitrate and potassium, WUE, NUE, and KUE. T60 reduced the plant growth by half. The largest growth was between 15 and 30% of the level of use of EAW. Two different models were constructed according to each plant. It is possible to have a small depletion in the available water and still have plant growth, if there is a balance between the air and water needs of the substrate.

The response of pepper (Capsicum annuum L.) to Ammonium-N was studied in a multispan greenhouse under soilless culture using coir fiber as substrate. Ammonium-N application rates were 0, 2, 4, 6 an...

French lavender (Lavandula dentata L.) is of great ornamental, medicinal, and aromatic interest. It is generally propagated vegetatively using stem cuttings. When using artificial lighting, a specific light composition can modify the entire plant phenology and is a factor that can be managed in controlled conditions. This study evaluated the rooting of stem cuttings and growth of lavender under four spectral LED lights. The LED lights used were: T0 (white LED, Roblan®), T1 (AP67 Milky, Valoya®), T2 (NS1, Valoya®), and T3 (AP673L Milky, Valoya®). The first phase evaluated the rooting of stem cuttings and initial development. The plants were then transferred to plastic pots to evaluate plant growth. In both rooting and growing phases, the plant morphological characteristics and water and light efficiencies were evaluated. Nutrient-uptake efficiencies were also evaluated after the growing phase. It was observed that cuttings rooted under the influence of T1 showed greater height. After the growing phase, plants under T3 showed better results in electricity use efficiency, water use efficiency, and nutrient-uptake efficiency and less nitrate leaching. They also presented more uniform growth with a compact canopy. Thus, T1 was better for the stem cuttings rooting phase, while T3 was better for growth and energy efficiency.

Changes in plant responses have been associated with different fractions of the visible spectrum and light intensity. Advances in light-emitting diodes (LED) have enabled the study of the effect of narrow wavelengths on plant growth and antioxidant compound synthesis. LED technology also facilitates the incorporation of light sources in a controlled setting where light spectra and intensity can be regulated. The objective of this study was to compare the effect of two commercial light spectra (S1: standard white light with 32.8% blue, 42.5% green, 21.7% red, and 2.4% far-red; S2: AP67 spectrum, designed for horticultural growth, with 16.9% blue, 20.5% green, 49.7% red and 12.3% far red) at two light intensities [low intensity (78 μmol m–2s–1 of photons for S1 and 62 μmol m–2s–1 for S2, and high intensity (HI) (102 and 100 μmol m–2s–1 for S1 and S2, respectively)] on growth and antioxidant compound contents in two leafy vegetables: endive (Cichorium endivia L.) and lettuce (Lactuca sativa L.). Fresh weight (FW), dry weight (DW), and DW% of plants were taken as growth indicators. In addition, leaf number, soil plant analysis development index, leaf area (LA), and specific leaf area were also evaluated. Antioxidant synthesis was measured as total phenol content, total flavonoid content, and antioxidant activity. The results showed that S2 and HI increased the FW, DW, and LA in both species. On the other hand, antioxidant compound contents were significantly increased by HI but did not vary with the spectrum. Highlights - The spectra of LED affected leaf number in lettuce and endive. - S2 spectrum improved growth parameters of both leafy vegetables. - Light intensity improved growth parameters of both leafy vegetables. - Antioxidant compound contents were significantly increased by high intensity LED light.

The presence of micro and nanoplastics in the food chain constitutes an emergent multifactorial food safety and physiological stress problem, which must be approached with a strategic perspective since it affects public health when consuming products that have this pollutant, such as fish and crustaceans, fruits, and vegetables. In this review, the authors present the results by scientists from different disciplines who are dedicated to discovering their chemical constitution and origin, the contents of these microparticles in edible plants, the contamination of water-irrigated soils, the mechanisms that concentrate microplastics in these soils, methods to determine them, contamination of freshwater sources of cities, and the negative effect of nano and microplastics on various food products and their detrimental impact on the environment. Recent findings of plant uptake mechanisms complement this, but more research is needed.

Tomato fruit possess high lycopene concentrations, which increases after reaching the breaker stage of ripeness. Light emitting diode (LED) systems have emerged as a clean and efficient artificial lighting technique for use in horticulture. The objective of this research was to examine the effect of LEDs on postharvest and lycopene quality parameters. The effects on quality parameters were significantly different depending on the tomato fruit cultivar. The commercial and organoleptic quality parameters most affected were firmness and titratable acidity. The lycopene concentration in all tomato cultivars increased between 30% and 60% when they were exposed to LED light compared with dark-exposed fruit. One hour of LED light exposure per day during the postharvest phase of fruit increased commercial and organoleptic parameters, and increased the lycopene concentration. Fruit exposed to LED light with a high red:far red (R:FR) light ratio had increased firmness compared with those exposed to other types of white LED light. The highest R:FR ratio used in this study resulted in fruit with higher titratable acidity than those exposed to lower R:FR ratios. Overall, the results of this study demonstrated that the postharvest exposure of tomato fruit to LED light with a high R:FR ratio induces lycopene synthesis, with lycopene concentrations being 41% higher in comparison with exposure to darkness and 24% higher in comparison with exposure to other LED lighting conditions.

Made available in DSpace on 2018-12-11T17:15:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-11-08 An experiment was conducted to develop a model of vegetative growth based on the nitrate concentrations in nutrient solutions using the nutrient film technique and to determine the best cultivar for each concentration. The chicory cultivars (“Pão de Açúcar,” “Folha Larga,” “Precoce de Trieste” and “Catalonha”) and the subplots corresponded to different nitrate concentrations (6.68, 10.0, 13.32 and 16.64 mmol L−1). There was an interaction between the evaluated factors, such that there was no similarity in the response of the chicory cultivars to the N concentrations in the nutrient solution. The most productive chicory cultivar was “Pão de Açúcar,” which exhibited 10.5% higher productivity than the average, and the least productive was “Folha Larga,” which showed approximately 8.5% lower productivity than the average. Departamento de Produção Vegetal Faculdade de Ciências Agrárias e Veterinárias Campus de Jaboticabal UNESP–Universidade Estadual Paulista Departamento de Agronomía Universidad de Almería Departamento de Produção Vegetal Faculdade de Ciências Agrárias e Veterinárias Campus de Jaboticabal UNESP–Universidade Estadual Paulista

Thermography is a tool used in many scientific disciplines, including agriculture. Determining the behavior of a nutritive solution in soilless culture containers using substrates is very important in order to establish the position of drippers, drainage holes, the use of humidification agents, and fertigation management in culture units. This paper describes the application of thermography to determine the humidification bulb in horticulture crops to rapidly diagnose the best way to advance fertigation in different horticultural substrates in soilless culture. Thermography was seen to be an excellent tool for evaluating the movement and distribution of the nutritive solution within the soilless culture container with different substrates.

Modern agriculture has a growing level of technification, through the incorporation of new technologies of great utility in other disciplines different from the agricultural sector. The use of remote sensing systems to monitor the physiological state of crops by observing the volume and appearance of the roots is another example of its application. These systems are based on the detection and recording of spectral variations of crops both in the range of visible radiation and within the electromagnetic spectrum in the infrared range. Thermography is a visual tool that has found applications in agriculture. The monitoring of water status through the observation of crop roots is essential to optimize the use of water in agriculture, as well as its development and final production. The efficiency of root growth in basil crops has been analysed in a chamber with controlled humidity and temperature. The aim of this work was to demonstrate a better efficiency of root analysis with a first non-invasive and environmentally friendly method, visually, using thermal imaging and digital processing in the evaluation of radical growth versus two other conventional methods: traditional standard analysis and invasive analysis with digital image treatment. The results also showed advantages in the use of thermographic images compared to the use of RGB images for roots smaller than 1 mm.

The bagasse of mezcal maguey and the fiber of coconut fruit are organic byproducts of the mezcal and copra agro-industries in Oaxaca, Mexico. The effects of different particle sizes and prior usage times as substrates on the production and quality of tomato (Lycopersicon esculentum Mill) were studied. Three independent and simultaneous experiments were conducted in multi-tunnel greenhouses. Three prior growing cycles of tomato crop, each 150 days in length days of use (DOU), were used for the usage time experiments with mezcal maguey bagasse as the growth medium. In the first experiment, tomato plants grown on substrate with 150 DOU produced the highest yields, the largest number of commercial quality fruits and the fewest non-commercial quality fruits. In the second experiment, the combination of fine particle size and maguey bagasse substrate with 150 DOU produced the highest yields. In the third experiment, fine and medium-sized particles of maguey bagasse and coconut fiber produced the highest yields....

The growth and essential oil (EO) production of parsley were evaluated in response to salinity and nutrient solution concentrations in a soilless culture. Parsley plants that were 60 days old were potted in a coconut fiber and peat moss medium and were treated with four different nutrient solutions, including T1, T2, T3 and T4. The T1 nutrient solution was the standard, the T2 and T3 solutions contained incremental macronutrient concentrations with an electrical conductivity (EC) of up to 2.2 and 3.2 dS m−1, respectively, and the T4 solution was the same as T2 but with sodium chloride (NaCl) and an incremental macronutrient concentration with an EC of 3.2 dS m−1. Next, these plants were grown for 90 days in a greenhouse with natural daylight in Nador, Morocco. Shoot and root growth significant decreased with increasing EC. However, the salinity that resulted from the addition of NaCl did not affect plant growth in the nutrient solutions. The optimum obtained growth and EO production were 1.2 and 2...

Commercialization of watercress in the Sierra Norte mountain range in Oaxaca, Mexico principally relies on harvesting plants growing on riverbanks; however, semi-intensive cultivation throughout the year could be established as an alternative for the region. With this as an objective, the present study was carried out using the laminar flow of nutrients technique to evaluate four solutions of different macronutrients and four shade percentages. Treatment distribution was formulated according to a bifactorial arrangement. Four harvest periods were employed, in April, June, September, and November of 2010. Yields and vegetative growth of watercress decreased linearly with increasing shade levels. The best results were obtained with a nutrient solution using an electrical conductivity (EC) of 0.90 dS m−1. Shade cloth percentages higher than 10% caused a significant decrease in total cycle production; the use of shade cloth is not recommended during seasons with low incident radiation.

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.

Aquaculture effluent can supply certain plant nutrients in adequate amounts. However, the nutrients present in the fish waste solution are not balanced. Mixing this effluent in an independent unit with a hydroponic nutrient solution can help to optimize conditions for the plants and minimize such drawbacks. The objective of this work was to assess the crop production and the nutritional responses of Pelargonium zonale fertigated with different percentages of fish wastewater. Five treatments were performed: 100NS, 75NS + 25AS, 50NS + 50AS, 25NS + 75AS and 100AS, where AS is the fish wastewater and NS a hydroponic nutrient solution. The species used to provide the fish waste solution was tilapia nilotica (Oreochromis niloticus). The results of this assay show that: i) fish wastewater can be utilized for the fertigation of Pelargonium zonale (a short-cycle crop) as there are no differences in the leaf, stem-petiole and flower dry matter, leaf water content, leaf area, plant height and leaf color compared to Pelargonium zonale fertigated with a chemical fertilizer; ii) the application of 75NS + 25AS accelerated flowers, shoots and leaves production. A higher percentage of fish waste solution mixed with the applied nutrient solution significantly reduces the K concentration in the nutrient solution and in the leaf; however, tilapia waste solution supplies adequate N, P and Ca nutrients to the pelargonium plants. Therefore, the reuse of fish waste solution can reduce the application rate of some inorganic fertilizers, which in turn can reduce the cost of fertilizers while preventing environmental pollution.

□ Plants from 60-day-old Lime Thyme (Thymus citriodorus) cuttings were potted in a medium of coconut fiber and peat moss and were treated with three different nutrient solutions: T1, T2, and T3. T1 was a standard nutrient solution; T2 was incremented with macronutrients up to an electrical conductivity (EC) of 2.8 dS m−1; and T3 was the same as T1 but incremented up to an EC of 2.8 dS m−1 with sodium chloride. The plants were then grown for 90 days in a greenhouse with natural daylight in Almeria, Spain. Root growth was not affected by the treatments. The dry weight of the leaves and the total dry weight of the plants benefited from the salinity. The specific salinity of the sodium chloride negatively affected growth compared to the same salinity in the complete nutrient solution.

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 NO3-and K+ contents and flux in xylem sap collected from cut stems of tomato seedlings, based on electric conductivity (EC) tests among five nutrition solutions for 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 NO3- 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.

The soilless culture of vegetables in protected environments has increased in southern Mexico. However, the use of materials such as mineral wool or perlite as substrates is expensive and unsustainable. Therefore, the use of alternative, local materials such as the waste from mescal and coconut industries, including maguey (Agave spp.) bagasse, coconut fruit fiber and dust, as well as non-metallic mining products, such as vermiculite, is desirable. In this study, the physical, chemical and biological properties of vermiculite, coconut fiber, and maguey bagasse were determined, and their potential for cultivating melons (c.v. ‘Magno F1’) and tomatoes (Mill. c.v. ‘Don Raul’) was evaluated. Moreover, 13 different substrates, based on combinations of the aforementioned materials, were analyzed. Materials were characterized at the Oaxaca Unit of the National Polytechnic Institute, and experiments were conducted in a multi-tunnel greenhouse in a randomized block design. Results indicated that materials possesse...

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 an...

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 sugg...

Root temperature may affect the production of greenhouse vegetables under soilless culture. Four independent experiments were carried out over two consecutive crop cy- cles 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 Almer´ ia (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, re- sults 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 param- eters, 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.

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.

Made available in DSpace on 2018-12-11T17:25:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-01-01 An experiment was carried out from February 25 till April 10 of 2010 at the Jaboticabal campus of the Paulista State University (UNESP), state of São Paulo, Brazil, viewing to find out which would be the optimum and the phytotoxic levels of iron in the nutrients solution for common chicory (Cichorium intybus) plants. Iron concentrations in the nutrients solution were of 0.9, 2.7, 8.3, and 25 mg L−1. These treatments were replicated 4 times and the experimental units were distributed according to a randomized complete block design. The nutrient film hydroponic technique (NFT) was used. Growth parameters such as plant height and number of leaves as well as reproductive parameters such as green and dry mass production were evaluated. The optimal concentrations were found to be between 2.7 and 8.3 mg L−1 of iron in the nutrients solution. The concentration of 25 mg L−1 caused toxicity, although no visual sign of iron in excess was observed. Plant Production Departament, Universidade Estadual Paulista (UNESP) Departamento de Agronomía, Universidad de Almería Plant Production Departament, Universidade Estadual Paulista (UNESP)

El objetivo de este trabajo fue evaluar la tolerancia al deterioro y la viabilidad de semillas de maíz en inmersión en agua caliente. Se evaluaron tres cultivares de maíz: País Tuxpeño (PT), X´nuuknal (X) y Sinaloa (S) que se sometieron a 0, 2, 4, 6 y 8 segundos de inmersión en agua a 100°C, en la producción de germinados para forraje. El estudio se realizó en Conkal, Yucatán, México en junio de 2011. Las variables evaluadas en semillas fueron: peso inicial (PIS), porcentaje de germinación (PG), número medio de días a germinación (NMDG) e índice de velocidad (IVG); en plántulas: peso fresco (PF), seco (PS) y la relación producción de biomasa por unidad de peso de semilla (PF:PIS). Los resultados mostraron diferencias significativas (P≤0,05) en todas las variables, excepto en NMDG. El PG fue de 96, 74 y 55% para PT, X y S, respectivamente. La inmersión por 2 s incrementó el PG, IVG, PF, PS y PF:PIS en X y S pero con inmersión por 4 y 6 s estas variables disminuyeron. Por el contrario, el PT inmerso por 2 s disminuyó el PG al 75%, pero con inmersión por 4 y 6 s todas las variables mostraron valores ascendentes. El tiempo de inmersión por 8 s afectó severamente a los tres cultivares, siendo PT el menos afectado ya que el PF solamente disminuyó el 35%, mientras que para X y S el decremento fue de 61% y 42% respectivamente. En conclusión, PT presentó mayor tolerancia al deterioro por inmersión en agua caliente y por tanto, es el más recomendado para la producción de germinados para forraje verde.

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.

Nitrate accumulation in vegetable represents a serious threat to man's 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.

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 consisted of three replicates. The experiments were carried out with 45‐day‐old plants. Xylem sap samples were obtained by decapitating the plant during the 35th day in NFT at about 1 cm above the root system. The sap flux rate was strongly correlated (p > 0.999) with the proposed model of a chronophysiological rhythm. Diurnal variations of inorganic ions clearly indicate that ion transport rates varied widely with time and also followed a proposed chronophysiological rhythm. The rhythmic model presented may provide a framework for the explanation of short‐ and long‐term variations in xylem sap concentration‐flux relationships. Additionally they may contribute to the knowledge of long distance transport processes and the variations in nutrient uptake by plants.

The present study was conducted during four consecutive vegetative cycles in deciduous fruit trees of agricultural value, almond, apple, pear, pomegranate, hazelnut, persimmon, and fig. Leaves were sampled on six occasions from the middle third of branches from the entire circumference of the crown at different stages of the vegetative cycle, and analyzed in order to determine levels of total and soluble N, P, K, Ca, and Mg. The changes over time in total and soluble levels of the N‐10P‐K ternary group did not significantly affect the relative proportions of the components. Relative levels of P and N varied slightly in almond, hazelnut, persimmon, and fig. By constrast, antagonism between K and Ca led to significant changes in ion levels in the K‐Ca‐Mg ternary group. The optimal levels of ions varied among the different species. In apple, total N‐10P‐K showed a high optimal value (59–28–15), while soluble N‐10P‐K was comparatively low (30–44–26). The lowest figures for both total and soluble N‐10...

Perennial deciduous plants were studied during their vegetative cycles. Leaves were sampled regularly every 15 days throughout this period in order to determine total and soluble iron (Fe) indices, physiological balances, and micronutrient levels. Analysis of variance and coefficients of variation were high for Fe indices and micronutrients between samples. The values of interaction between variables were not high. The optimium value of total Fe index ranged from 0.72–0.74 in almond to 1.11–1.14 in pomegranate. Optimum values for soluble Fe index ranged from 0.77–0.83 in almond to 1.18–1.29 in pear. Similar ranges were observed for soluble and total micronutrients and ternary groups. The evolution of the physiological ternary groups demonstrates ionic imbalances in apple in total Fe and manganese (Mn) as a result of excess levels of total zinc (Zn) during the final phase of fruit development. During this phase, total and soluble Fe and Mn also show significant interactions in persimmon. In apple,...

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.

La cáscara del fruto del almendro (Prunus dulcis L.) es un residuo orgánico de la industria de los frutos secos, con mínima utilización en los países mediterráneos. Con el propósito de utilizar este material como medio de cultivo para hortalizas, se estudió el efecto del tiempo de uso como sustrato en función de sus propiedades físicas y químicas. Los experimentos se hicieron en invernadero tipo parral. El tiempo de uso de la cáscara de almendra como sustrato, estuvo determinado por tres ciclos de tomate (Lycopersicon esculentum Mill.) y dos de melón (Cucumis melo L.) de 165 y 100 d respectivamente, cultivados en sacos de 25 L. Para el análisis del sustrato se tomaron muestras de tres sacos de los sustratos reutilizados, por cada ciclo de cultivo. Durante los primeros 165 d de uso, el porcentaje en peso de partículas medianas (de 0.125 a 2 mm) disminuyó, mientras que las gruesas (de 4 a 8 mm) aumentaron. Hasta los 430 d de uso, tanto las partículas finas (menores a 0.125 mm) como las muy gruesas (8-16 mm) se incrementaron. A través del tiempo todas las propiedades físicas variaron significativamente. La densidad aparente disminuyó en 0.28 g cm-3, mientras que el espacio poroso total aumentó en 27 %. La mojabilidad y la contracción aumentaron más de 100 %, de acuerdo con el intervalo óptimo. Las relaciones aire-agua también se modificaron y fue a los 430 d de uso cuando la mayoría de sus valores se ubicaron en el óptimo. Los valores de las propiedades físicas y químicas fueron mejores a través del tiempo y se ubicaron en el intervalo óptimo, de modo que dicho sustrato se puede utilizar hasta 695 d.

Se estudió el contenido de nitrato en lechugas cultivadas en sistemas hidropónicos. Altos niveles de nitrato pueden ser dañinos a la salud humana. La Comisión Europea indica que las plantas de lechuga cultivadas en invernadero en período invernal deberían contener una concentración de nitrato foliar menor a 4.500 mg/kg (peso fresco). En este estudio se determinaron los contenidos de nitrato de lechugas cultivadas en los sistemas hidropónicos de mesa flotante y nutrient film technique (NFT), en invernadero no calefaccionado y en invierno. Cuatro experimentos se realizaron en Talca, Chile, en período invernal (mayo a septiembre). Tres cultivares de lechuga tipo Española (Lactuca sativa L. var. capitata) fueron evaluados: “Loreto”, “Floresta” y “Esmeralda”. En el sistema flotante, el contenido de nitrato foliar fluctuó entre 1.344 y 3.839 mg/kg y desde 1.754 a 2.157 mg/kg a inicios y término del período invernal, respectivamente. Los contenidos de nitrato en cultivares de lechuga cultivados en el sistema NFT fluctuaron desde 2.552 a 2.818 mg/kg y entre 2.676 a 3.100 mg/kg a inicios y fin del invierno, respectivamente. Ninguno de los cultivares de lechuga sobrepasó el contenido máximo estipulado por la Comisión Europea y tampoco existieron diferencias consistentes entre ellas.

The concept of active Fe has been seldom applied to the extractable fraction to study its changes through time. Neither its relationships to physiological balance of Fe Index in plants has been investigated to any extent. The study reported here was conducted on Castanea sativa Miller trees, autoctonous, not grown by man, as the relationships il‐plant is better balanced. In this work we studied the contents and changes of P, K, Fe, Mn and Zn which are found in extractable form in leaves, the balances of Fe‐Mn‐Zn, and the Fe Index obtained from data of the extractable fraction and their changes throughout the vegetative cycle. The data obtained were related to those obtained from the analysis of the total plant to study their significance in the foliar analysis values, and the possibility to diagnose Fe disorders from balances Fe‐Mn‐Zn and Fe Index obtained from the extractable fraction. Likewise, the relationships among the extracted nutrients and the total present in the foliar tissues were also...

The Iron Index has been developed to permit its application to the diagnosis and correction of iron chlorosis in culture growth. The stress in the ratio Fe‐Mn‐Zn enables us to diagnose deficiences with respect to some of these elements in the absence of visual signs. Both Iron Index and ratio Fe‐Mn‐Zn, P/Fe, Ca/Fe, Mn/Fe and Zn/Fe were applied to the nutritional research into several lots of walnuts (Juglans regia L.) autochthonous from Sierra Nevada, Spain, in the same climatic and edaphologic conditions. These walnuts were sampled from the time their leaves were completely developed to their old age. Leaves were analysed and the mentioned index and equilibriums determined, being possible to verify the metabolic fluctuations and their correspondence with the morphological state in which the plants were every instant. There are no significant differences among each lot. They initially present very high nutritional levels, then they get stabliized, and decline abruptly later on. We deduce that dur...

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...