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This trial was carried out to study the nutritional and productive behavior generated by modifications in the salt concentration in the nutrient solution for Cordyline fruticosa var. Red Edge plants. The anions studied were chloride (Cl), nitrogen (N), and phosphorus (P). Four treatments were tested: T1 [control, 1.5 dS m−1, 14.3 mmol L−1 sodium chloride (NaCl)], T2 (2.5 dS m−1, 22.2 mmol L−1 NaCl), T3 (3.5 dS m−1, 32.7 mmol L−1 NaCl), and T4 (4.5 dS m−1, 38.2 mmol L−1 NaCl). At the end of the cultivation, leaf, petiole, shoot and root fresh and dry weights, elemental extractions, and elemental concentrations were determined. Nutrient concentrations and total plant uptake (extraction) were calculated from the dry matter. The treatment T2 induces a blade protection mechanism, which consists on the accumulation of chloride (Cl−) in root and vessels; so, leaf storage is reduced, avoiding damages. Petiole also contributes to this protection, acting as a salt pool. As NaCl concentration in the nutritive solution arises, N plant concentration increases significantly although there are no significant differences between T1 and T2. With high salinity levels, P in vessels is reduced, whereas root extraction and concentration increases. The greatest N and P extractions are observed in T2, which is due to its higher dry matter. Chloride extractions are lower in T1 than in the other treatments. [ABSTRACT FROM PUBLISHER]

The reuse of substrates for more than one growing season is an excellent alternative to reduce production costs and to improve the sustainability of the ornamental plant production system. The objectives of the present trial were to study the effects of substrate reuse on Lilium var. Helvetia plants cultivated in shipping crates in a polyethylene greenhouse, as well as possible changes in the physical and physical–chemical properties of the substrates employed. Peats used during two and three cultivation cycles and new unused peat were tested. The reused substrate reduces the particle fraction with higher diameter size, porosity, and organic matter and increases particle bulk and substrate carbon (C) / nitrogen (N) ratio, due to the substrate decomposition. However, it does not affect flowers, flower stems and leaves, and dry and fresh matter. The level of phosphorus (P) and magnesium (Mg) in leaf, as well as nitrate, potassium (K), and Mg in the substrate solution are similar among the three kinds of substrates studied. Nevertheless, the substrate used for three cultivation cycles leads to increases in organic N and K and decrease of calcium in leaves. [ABSTRACT FROM PUBLISHER]

The aim of this trial was to study the nutritional behavior generated by modifications in the salt concentration in the nutrient solution used for the fertigation of Cordyline fruticosa var. Red Edge plants. Four treatments were tested: T1 [control, 1.5 dS m−1, 14.3 mmol L−1 sodium chloride (NaCl)]; T2 (2.5 dS m−1, 22.2 mmol L−1 NaCl); T3 (3.5 dS m−1, 32.7 mmol L−1 NaCl); and T4 (4.5 dS m−1, 38.2 mmol L−1 NaCl). There is an accumulation of sodium (Na+) in roots, stem, and petiole when salinity increases, which avoid leaf damages. Potassium (K) concentration increases with the intermediate saline treatments in stems and leaves but decreases when plants are fertigated with T4. Calcium (Ca) accumulates in roots with T3 and T4, in stems with T4, and in petioles and leaves with T3. Magnesium (Mg) concentration is greater in stems, petioles, and leaves of T4, but is greater in roots of T3. Plants fertigated with the three saline treatments extract 1.4 times more Na+ than T1 plants. The greatest K+ extraction is observed in T2, followed by T3, and T4. T2, T3, and T4 plants extracted more Ca2+ than T1 plants. Finally, Mg2+ extractions in T3 are twice as much as they are in T1, while in T4 and T2 are much greater. [ABSTRACT FROM PUBLISHER]

The objectives of this article were to analyze the evolution of the nutrient parameters of the leachates collected from Syngonium podophyllum var. Silver plants cultivated for 20 weeks in a buried greenhouse with four methods of fertilization. The treatments were T1, standard liquid feeding (SLF) [7.0 mmol L−1 nitrate (NO3 −) nitrogen (N), 0.3 mmol L−1 phosphorus (P), and 3.5 mmol L−1 potassium (K)] after transplanting; T2, liquid feeding soluble fertilizer (LFSF) [6.9% NO3 − N, 11.1% ammonium (NH4 +) N stabilized by 3,4-dimethylpyrazole phosphate, 8.0% P2O5, and 14.0% K2O] after transplanting; T3, controlled release fertilizer (CRF I) (7.4% NO3 − N, 8.6% NH4 + N, 8.0% P2O5, and 12.0% K2O) applied before planting and half concentration of SLF from 45 days after transplanting; and T4, controlled release fertilizer (CRF II) (8.5% NO3 − N, 7.5% NH4 + N, 8.0% P2O5, and 12.0% K2O) applied before planting and half concentration of SLF from 45 days after transplanting. Solution pH, electrical conductivity (EC), NO3 − N, NH4 + N, K, and P concentrations in the leachate were analyzed weekly. Plant quality was assessed at the end of the trial through objective and subjective parameters. Significant differences among the different fertilization methods were observed. CRF treatments resulted in the greatest nutrient leachate concentration during the first 6 weeks of the study, and afterward it decreased gradually until the end of the cultivation. CRF I showed greater leachate concentrations of N, P, and K than the others during the first half of the study. The concentrations of NO3 − N and P from all the fertilizer types were often above the permissible levels cited in the federal Clean Water Act. The best-quality plants were obtained with CRF II, whereas the greatest height and Aerial Dry Weight (ADW) were obtained with CRF treatments and the greatest Root Dry Weight (RDW) was obtained with the NH4 + N treatments. [ABSTRACT FROM PUBLISHER]

Whitewash is a sustainable technique in Mediterranean greenhouses. where high radiation during spring and summer generates microclimate of high temperature and low Vapour Pressure Deficit (VPD). The aim ofthe present research was to study the effect of polyethylene film covering whitewashed and control on global radiation, VPD and air temperature. This study was conducted in a polyethylene multitunnel greenhouse without crop in the University of Almeria (Spain). The covering transmission coefficient in the greenhouse is not constant along the spectrum. Under whitewashed condition, greenhouse presented a reduction of the air temperature and global radiation of 32 and 41 per cent and an increase of 46 per cent in the VPD. Comparing with the external condition, the average reduction of radiation was 54.7 per cent and 29.6 per cent, the average increment ofVPD was -2.63 kPa and -1.42 kPa and the average diminution of temperature was 10.8 °C and 7.4 °C in the control greenhouse and with whitewash, respectively. [ABSTRACT FROM AUTHOR]

Irrigated agriculture depends on adequate and quality water supplies. As the level of salt increases in an irrigation source, the quality of that water for plant growth decreases. Crop plants are usually nonhalophytes that tolerate only moderate salt concentrations. Under salinity, they accumulate salt in their aboveground organs and, to a smaller extent, in roots. High salinity reduces plant growth and leaf area, which prejudices quality, especially in ornamental crops. The study of the behavior of ornamental plants that are tolerant to saline waters can be an advantage in areas with poor quality waters. The aim of this work is to study the influence of the fertigation water salinity on the nitrogen metabolism of Cordyline fruticosa var. 'Red Edge,' known as ti plant, Hawaiian ti, cordyline, or good luck plant. Four nutrient solutions with different electrical conductivity (EC) levels were applied: T1 (1.5 dS m-1), T2 (2.5 dS m-1), T3 (3.5 dS m-1), and T4 (4.5 dS m-1), obtained with the application of different amounts of sodium chloride (NaCl) to the fertigation water. As salinity increases, nitrogen concentration in leaves does not change, but it increases in roots. In leaves, nitrate reductase (NR) in vivo activity declines when salinity increases; when a substrate [nitrate (NO3 -)] or a cofactor [molybdenum (Mo)] is added, NR activity increases. Potential NR activity (NO3 - + Mo) shows no significant differences between treatments; this indicates that NR synthesis is not affected by salinity. So, the diminution of the NR in vivo activity suggests a NO3 - and Mo level metabolic imbalance. In roots, Mo is more restrictive of the NR activity than the NO3 - substrate level. There are more amino acids in T1 than in T4, but it seems that there are no significant differences in T2 and T3. No significant differences are observed in the protein content; this indicates that amino acid diminution is due to the maintenance of the protein content. In conclusion, it can be said that the increased activity of NR in roots may constitute part of an adaptation strategy of the plant to an increasing salinity in the growing medium. [ABSTRACT FROM AUTHOR]

Crop plants are usually nonhalophytes that tolerate only moderate saline concentrations; under salinity, they accumulate salt in their aboveground organs and, to a smaller extent, in roots. Enhanced synthesis of determined secondary metabolites (such as proline, phenolics, or malondyaldehide) under stressful conditions is believed to protect the cellular structures from oxidative damage, in addition to the osmotic advantage for the plants. The aim of this work is to study the influence of the fertigation water salinity on osmoprotectant content in Cordyline fruticosa var. 'Red Edge.' Four nutrient solutions with different electrical conductivity levels were applied: EC1.5 (1.5 dS m-1), EC2.5 (2.5 dS m-1), EC3.5 (3.5 dS m-1), and EC4.5 (4.5 dS m-1), obtained by the addition of different quantities of sodium chloride (NaCl) to a basic nutrient solution (EC 1.5 dS m-1), followed by stirring to dissolve the salt and make the solution homogeneous. The results show that malondialdehyde (MDA) content is not a good indicator of plant stress, as levels in EC1.5 and EC4.5 are similar, but flavonoids, phenols and sugars contents are more useful indicators, because the highest values in leaves are found with the more saline treatment. Proline plays an osmoregulatory role, increasing in roots when NaCl concentration in the nutrient solution is too high but also when it is too low. [ABSTRACT FROM AUTHOR]

Substrate solution constitutes a useful tool to evaluate the nutritional status of the root zone; this work studies the possibility of using the drainage and the suction cup solution to evaluate the nutritional parameters in leaching, avoiding analysis and simplifying the diagnosis model. The trial was carried out in an INSOLE-type greenhouse (buried solar greenhouse), from 19 April to 19 September 2004 (20 weeks). There were four mineral fertilizer treatments: (SLF) standard liquid feeding, (LFSF) fertilizer (17-8-14) containing both nitrate (NO3 --N) and ammonium (NH4 +-N) and a nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), and two coated controlled release fertilizers (CRF), the first one with Basacote Plus (16-8-12) + half concentration of SLF and the second one with Osmocote Plus (16-8-12) + half concentration of SLF. Nutrient, substrate, and leachate solutions were collected fortnightly. The parameters analyzed were pH, electrical conductivity (EC), NO3 --N, and NH4 +. There were significant differences between substrate solutions and leaching during the trial, especially when slow-release fertilizers were applied. Leaching showed more extreme pH and EC levels than suction-cup solutions, especially in the treatment with Basacote; however, NO3 --N and NH4 +-N exhibited higher values in the suction-cup solutions. [ABSTRACT FROM AUTHOR]