Pedro García-Caparrós

Integral Management of Irrigation Water in Intensive Horticultural Systems of Almería

The development of intensive horticulture in Almeria, with a huge increase in greenhouse surface area, is related to three essential factors: climatic characteristics, groundwater use and mulching sandy soil. The purpose of the present paper is to draw a picture of the integral management of water irrigation in the intensive horticultural systems in the region, by identifying the most significant water resource contributions and alternative water resources. Results indicate that the use of groundwater for the irrigation of horticultural crops in the greenhouses presents a high degree of overexploitation of the aquifers, but due to the continuous search for alternative water resources, such as desalinated and reclaimed water, as well as in-depth knowledge of the integral management of water irrigation through automated fertigation and localized irrigation systems, the current status of the water resources could be sustainable. Moreover, being conscious of the pollution generated by agricultural leachates, the horticultural system of Almeria is implementing complementary sustainable systems such as recirculation, cascade cropping systems and phytodepuration for the reuse of the leachate. Considering all these factors, it can be concluded that the intensive horticultural system is on the right path towards respecting the environment and being sustainable in terms of water use.

Yield and Nutritional Status of Cucumis sativus under Different Growing Conditions in the Pacific Coast of Ecuador

ABSTRACT The growth of cucumber under open field conditions in the coast of Ecuador results in low yields being the growth under protected conditions a tentative solution, but there is little information about the nutritional status of this crop in this region. The objectives were to determine the yield, nutritional status as well as the water and nutrient use efficiencies. The different growing conditions were: multitunnel greenhouse with soilless system (GSL), multitunnel greenhouse with soil system (GS) and open field conditions with soil system (OFS). Cucumber plants grown under GSL had the highest yield. The nutrient concentration in leaf showed different trends: nitrogen (N), calcium (Ca) and iron (Fe) remained unchanged. Phosphorus (P), potassium (K), magnesium (Mg), copper (Cu), zinc (Zn) and manganese (Mn) showed variations according to the growing conditions and phenological stages. The highest values of water and nutrient use efficiencies under GSL were related to the highest yield.

Effects of Salinity on Growth, Water-Use Efficiency, and Nutrient Leaching of Three Containerized Ornamental Plants

ABSTRACT The scarcity of water in the Mediterranean area has frequently led to the use of saline water to irrigate ornamental plants in nurseries. Aloe vera L. Burm, Kalanchoe blossfeldiana Poelln, and Gazania splendens Lem. plants were grown in a greenhouse from the University of Almeria in containers with a mixture of sphagnum peat moss and perlite in order to evaluate the effect of salinity levels on plant growth, water-use efficiency, and nutrient leaching. The experimental design consisted of three salinity treatments, four blocks, and four plants (one plant per container) per treatment-block giving a total of 12 plants per species plus border plants placed around the perimeter of the treatment plants to maintain uniform growing conditions for treatment plants. At the end of the experiment, plant dry weight and water-use efficiency were assessed for each salinity treatment. Leachate was collected weekly and analyzed for concentrations of nitrate-nitrogen, phosphate-phosphorus, potassium, calcium, and magnesium (NO3–N, PO43–P, K+, Ca2+ and Mg2+). Increasing salinity levels of irrigation water reduced the plant dry weight in all species and affected the leachates volume and their nutrients concentrations. We suggest the use of low salinity levels in water to improve the growth and to reduce the environmental impacts of nutrient runoff.

Nutritional and physiological responses of the dicotyledonous halophyte Sarcocornia fruticosa to salinity

Sarcocornia fruticosa (L.) A.J. Scott is a dicotyledonous halophyte that grows in areas with an arid climate such as the marshes of southern Spain. The species has potential uses for saline agriculture and biofuel production, but the effects of salt stress on its nutrition and physiology remain unclear. Plants of S. fruticosa were grown in pots with a mixture of sphagnum peat-moss and Perlite. In order to evaluate the effects of different levels of salinity, five treatments using different NaCl concentrations (10 (control), 60, 100, 200 and 300 mM NaCl) were applied over a period of 60 days. At the end of the experiment, the dry weight, the biomass allocation and the tissue water content were measured for each salinity treatment. The net uptake of various nutrients and their translocation rates were calculated for each salt treatment. Salt loss, shedding of plant parts and succulence in shoots were evaluated together with the K+/Na+ ratio, K-Na selectivity, concentrations of osmolytes and their estimated contributions to the osmotic potential. Our results showed that S. fruticosa can maintain its major physiological processes at 60 mM NaCl without significant dry weight reduction. Higher salinity resulted in negative values for net uptake and translocation rates from roots to shoots of N and P. As might be predicted from other dicotyledonous halophytes, S. fruticosa plants increased Cl– and Na+ uptake using both as osmotica instead of organic osmolytes. However, to survive salinity, this species has also evolved others mechanisms such as shedding old shoots, increased succulence in shoots at higher salt concentrations and the ability to maintain a lower K+/Na+ ratio and higher K-Na selectivity in all organs.

Water and Nutrient Uptake Efficiency in Containerized Production of Fern Leaf Lavender Irrigated with Saline Water

The scarcity of water in the Mediterranean area has frequently led to the use of saline water for irrigation. Container grown ornamental production has relatively high rates of water and nutrient loss from fertigation. A better understanding of water and nutrient use efficiency with water that has elevated levels of saline could reduce runoff water and its environmental impact. Fern leaf lavender (Lavandula multifida) plants were grown for 8 weeks in plastic containers with a sphagnum peatmoss and perlite substrate (80:20 by volume) to evaluate the effect of saline water [2.0 (T1 or control), 4.5 (T2), or 7.5 (T3) dS m] on water and nutrient uptake efficiency. Leachate was collected to determine runoff volume and composition which included nitrate-nitrogen (NO3 -N), phosphate-phosphorus (PO4 -P), and potassium (K) concentration. Plant dryweight (DW) and nutrient content were determined in plants at the beginning and at the end of the experiment to establish the nutrient balance. Increasing salinity levels of irrigation water did not significantly reduce either the plant DW or the water use efficiency (WUE). Based on nutrient balance, the increasing salinity (2.0 to 7.5 dS m) affected the plant nutrient uptake efficiency, which decreased 28% for N, increased 26% for P from the lowest to highest sodium chloride levels; whereas K did not show a clear trend. Nutrient runoff increased (28% N, 9% P, and 27% K) to the environment from the lowest to highest sodium chloride levels.

Ion Homeostasis and Antioxidant Defense Toward Salt Tolerance in Plants

The increase of salinity in the soil represents a great threat at worldwide level since it reduces the plant growth and the productivity. The main problems of salinity are related to the osmotic effect and specific ions. The changes in cytosolic Ca2+ concentration are supplied from the apoplast or internal stores like mitochondria or vacuoles, and they educe several purposes at cellular levels such as signal transduction in plant-defense responses against stresses. Even though the Cl− movement response to salt stress is less investigated, it is well known that their entrance through plasma membrane is related with a raising external Cl− concentration and the relocation of Cl− from the cytoplasm into the vacuole of root cells ends with delimitated concentrations. Due to the chemical uniformity between Na+ and K+, there is a high competence between them for binding sites in different physiological processes such as enzymatic reactions, protein synthesis, and ribosome functions; therefore, the cellular maintenance of Na+/K+ homeostasis is essential to overcome the salinity in plants. All of these responses are triggered by plants to maintain the ion homeostasis because it is an essential process for growth during salt stress. Also, plant cells are responsible for the reduction of toxic ions and the accumulation of crucial ions to maintain the ion homeostasis. Antioxidant defense system of plants is regarded as one of the vital mechanisms of salt stress tolerance by which plants cope with oxidative stress. Several recent studies indicated that both ion homeostasis and antioxidant defense systems are closely associated with salt tolerance. This review will be focused on current progress of nutrient homeostasis and antioxidant defense in plants under increasing saline conditions.

Nutrient demand modeling of a soilless cucumber crop under greenhouses conditions in a humid tropical climate

ABSTRACT This experiment was conducted in a greenhouse in Vinces Los Rios (Ecuador). The aim of this work is to evaluate the relationship between different parameters and the nutrient demand of a greenhouse soilless cucumber production system in a tropical climate as well as to propose an empirical model for the design of the nutrient supply to the system. Considering the results obtained in this experiment, there was a high correlation between nutrient demands of the system with nutrient supplies and water uptake but not with leaf area index. With respect to the models, nutrient supplies and leaf area index were the most significant variables for nitrate (NO3−), chloride (Cl−) and manganese (Mn). For calcium (Ca2+), magnesium (Mg2+) and zinc (Zn), nutrients supply was the most significant variable and for the rest of nutrients [phosphates (H2PO4−), sulfates (SO42)−, potassium (K+), sodium (Na+) and iron (Fe)], the three variables assessed were significant.

Evaluation of the Nutrients Variability in Sap of Different Petiole Samples in Tomato Plant

ABSTRACT The aim of this trial was to study the variability of anions and cations concentrations in the different petiole samples: young leaves (YL), mature leaves (ML) and aged leaves (AL). The experimental design consisted of four blocks and four plants per block being each plant one replication. In each plant, petiole samples were collected at 135 days after transplanting (DAT) to determine chloride, nitrate-nitrogen, phosphate-phosphorus, sulfate-sulfur, sodium, potassium, calcium, and magnesium (Cl−, NO3–N, H2PO4–P, SO42–S, Na+, K+, Ca2+ and Mg2+) concentrations. Our results showed that the selection of sample petiole in the tomato crop did not modify the Ca2+, Cl−, SO42–S and Na+ concentrations, while NO3–N, K+, Mg2+ and H2PO4–P concentrations showed a great variability due to the selection of the sample petiole, therefore it is necessary to be careful with the sample selection.

Response of Container-grown Confetti Tree Irrigated with Runoff Water

This experiment measured plant growth of a halophyte (species adapted to saline conditions) confetti tree (Maytenus senegalensis) using runoff from kneeholy plants (Ruscus aculeatus). Three irrigation treatments were used, a standard nutrient solution or control (T0), runoff water collected from kneeholy plants irrigated with the standard nutrient solution blended 50:50 with tap water (T1), and 100% runoff water collected from kneeholy plants irrigated with the standard nutrient solution (T2), in which the nutrient concentrations were analyZed by highperformance liquid chromatography. Growth, photosynthetic parameters, and mineral composition were measured at the end of the experiment. Electrical conductivity and pH increased with increasing runoff application (decreased blending). Treatment 2 had significantly higher plant height, number of branches, number of leaves, leaf area index, and dry weight. Treatments 1 and 2 had significantly lower root lengths compared with the control. Chlorophyll concentration and green index color in leaves were greater in T2 and T1 than T0. The mineral composition of roots and leaves was affected by irrigation treatment, resulting in an increase of sodium and chloride concentration and a decline of nitrogen and phosphorous concentration compared with the control. The reuse of runoff water was beneficial for growing this commercially important halophytic species in Spain, a consideration that is particularly relevant in locations with water quality, quantity issues, or both.

Sodium Chloride Effects on Water and Nutrient Uptake Efficiency in Sarcocornia fruticosa Containerized Production

ABSTRACT The ability to produce native plants well adapted to the saline conditions without the production of nutrient-rich runoff will be a boon to nurseries hoping to reduce their environmental contamination impact and water use while at the same time producing quality plants to be used in the restoration of saline lands. Sarcocornia fruticosa plants were grown for 8 weeks in plastic containers with a source of sphagnum peat moss and perlite (80:20 v/v) to evaluate the effect of two salinity levels (2.0 (low-salinity treatment) and 7.5 dS m−1 (high-salinity treatment)) on plant growth, nutrient concentration in leachate and water and nutrient uptake efficiency and their losses. Leachate was collected to determine the runoff volume and composition, which included nitrate-nitrogen (NO3–N), phosphate-phosphorus (PO43–P) and potassium (K+) concentrations. Plant dry weight (DW) and nutrient content were determined in plants at the beginning and at the end of the experiment to establish the nutrient balance. Increasing salinity levels of irrigation water did not reduce either the plant DW or the water-use efficiency (WUE), but increased the volume of leachate per plant. The nutrient concentrations in leachates without significant differences between salt treatments exceeded the thresholds established by environmental guidelines, leading to a great risk of pollution. Based on nutrient balance, the irrigation with a higher salinity level reduced the plant nutrient uptake efficiency (10%, 18% and 12% for nitrogen (N), phosphorus (P) and potassium (K), respectively) and increased the nutrient losses (6% N, 7% P and 8% K), resulting in the recommendation to grow this species with the low salinity level based on the highest nutrient-use efficiency and the lowest levels of nutrient losses.