Standard Nutrient Solution Research Articles

Produção e qualidade da couve folha hidropônica sob estresse salino e concentrações de KNO3

ABSTRACT Potassium is a nutrient with the potential to increase plant tolerance to salt stress. The aim of this study was to evaluate the production and quality of kale subjected to salt stress and potassium concentrations in a protected environment. The experimental design was in split plots, with plots composed of five nutrient solutions (control treatment, S1 - standard nutrient solution prepared in low-salinity water, 0.5 dS m-1 (500 mg L-1 of KNO3), and four nutrient solutions prepared in brackish waters (3.5 dS m-1) containing four concentrations of KNO3 (S2 - 500 mg L-1, S3 - 625 mg L-1, S4 - 750 mg L-1, S5 - 1,000 mg L-1), and subplots represented by two leaf kale cultivars (Manteiga and Manteiga da Geórgia). Leaf production variables and post-harvest physical and chemical qualities were evaluated. The saline nutrient solution with the addition of NaCl (S2) reduced production but did not reduce the post-harvest quality of kale. The extra addition of KNO3 at 25% (S3) was efficient in reducing the deleterious effects of salt stress on the variables leaf length, leaf area, leaf production, and number of bunches. The cv. Manteiga da Geórgia was more tolerant to salt stress than the cv. Manteiga.

Influence of Cow Dung Extract Complemented with Nutrient Solution on the Growth Performance of Lettuce (Lactuca sativa L)

Limited studies have focused on plant growth performance using organic-based solutions complemented with mineral elements in a hydroponic system. Thus, this study aimed to investigate the growth performance of lettuce (Lactuca sativa L.) as influenced by cow dung extract combined with a hydroponic nutrient solution. Treatments considered as four different levels of aerated cow dung extracts (C), viz., C1 = 50 g l-1, C2 =100 g l-1, C3 =150 g l-1 and C4 =200 g l-1 and four strengths of standard nutrient solution (S), viz, S1 = 30% of standard nutrient solution, S2 = 40% of standard nutrient solution, S3 = 50% of standard nutrient solution and S4 = 60% of standard nutrient solution. The experiment was carried out using a deep flow technique in a semi-greenhouse. Various growth and physiological parameters were measured in this experiment. The obtained data were subjected to statistical analysis with 4 replicates by analysis of variance (ANOVA) using SPSS. In the case of growth parameters, the tallest plant (23.54 cm), maximum number of leaves per plant (17.01) broadest leaf (13.32 cm), and the highest fresh weight (112.05 g/plant) were recorded from C3 while the lowest in C1. For hydroponic nutrient solution, the tallest plant (23.13 cm), the maximum number of leaves per plant (16.66), the widest leaf breath (14.17 cm), and the highest fresh weight (116.0 g/plant) were recorded from S4 while the lowest in S1. On the other hand, physiological traits viz. leaf area, net assimilation ratio, and relative growth rate were statistically higher in C3 and lowest in C1. In the nutrient solution, all physiological parameters were highest in S4 and the lowest in S1. In the case of the interaction effect, the highest fresh weight and almost all the parameters were found best in C3S4 and the lowest in C1S1. Therefore, the analysis showed that in terms of growth promotion properties hydroponic nutrient solution along with cow dung extract had a substantial impact and C3S4 was the most preferable treatment combination. Based on these findings, in a hydroponic system, an inorganic nutrient solution combined with organic liquid fertilizer derived from cow dung extract (as an alternative nutrient source) requires further improvements to achieve optimal growth and yield.

Crosstalk between Ethylene, Jasmonate and ABA in Response to Salt Stress during Germination and Early Plant Growth in Cucurbita pepo.

The crosstalk of phytohormones in the regulation of growth and development and the response of plants to environmental stresses is a cutting-edge research topic, especially in crop species. In this paper, we study the role and crosstalk between abscisic acid (ABA), ethylene (ET), and jasmonate (JA) in the control of germination and seedling growth in water or in standard nutrient solution and under salt stress (supplemented with 100-200 mM NaCl). The roles of ET and JA were studied using squash ET- and JA-deficient mutants aco1a and lox3a, respectively, while the crosstalk between ET, JA, and ABA was determined by comparing the expression of the key ABA, JA, and ET genes in wild-type (WT) and mutant genotypes under standard conditions and salt stress. Data showed that ET and JA are positive regulators of squash germination, a function that was found to be mediated by downregulating the ABA biosynthesis and signaling pathways. Under salt stress, aco1a germinated earlier than WT, while lox3a showed the same germination rate as WT, indicating that ET, but not JA, restricts squash germination under unfavorable salinity conditions, a function that was also mediated by upregulation of ABA. ET and JA were found to be negative regulators of plant growth during seedling establishment, although ET inhibits both the aerial part and the root, while JA inhibits only the root. Both aco1a and lox3a mutant roots showed increased tolerance to salt stress, a phenotype that was found to be mainly mediated by JA, although we cannot exclude that it is also mediated by ABA.

γ-Aminobutyric acid (GABA) priming alleviates acid-aluminum toxicity to roots of creeping bentgrass via enhancements in antioxidant defense and organic metabolites remodeling.

γ-Aminobutyric acid alleviates acid-aluminum toxicity to roots associated with enhanced antioxidant metabolismas well asaccumulation and transportation of citric and malic acids. Aluminum (Al) toxicity has become the main limiting factor for crop growth and development in acidic soils and is further being aggravated worldwide due to continuous industrial pollution. The current study was designed to examine effects of GABA priming on alleviating acid-Al toxicity in terms of root growth, antioxidant defense, citrate and malate metabolisms, and extensive metabolites remodeling in roots under acidic conditions. Thirty-seven-day-old creeping bentgrass (Agrostis stolonifera) plants were used as test materials. Roots priming with or without 0.5mM GABA for 3days were cultivated in standard nutrient solution for 15days as control or subjected to nutrient solution containing 5mM AlCl3·6H2O for 15days as acid-Al stress treatment. Roots were sampled for determinations of root characteristics, physiological andbiochemical parameters, and metabolomics. GABA priming significantly alleviated acid-Al-induced root growth inhibition and oxidative damage, despite it promoted the accumulation of Al in roots. Analysis of metabolomics showed that GABA priming significantly increased accumulations of organic acids, amino acids, carbohydrates, and other metabolites in roots under acid-Al stress. In addition, GABA priming also significantly up-regulated key genes related to accumulation and transportation ofmalic and citric acids in roots under acid-Al stress. GABA-regulated metabolites participated in tricarboxylic acid cycle, GABA shunt, antioxidant defense system, and lipid metabolism, which played positive roles in reactive oxygen species scavenging, energy conversion, osmotic adjustment, and Al ion chelation in roots.

Improvement in Productivity and Quality of Soilless Saffron Crops by Implementing Fertigation

Saffron cultivation is important in global agriculture and is mainly flourishing in Mediterranean climates. Although it originated in Asia Minor, it is widely grown in regions such as Iran, India, Spain, Morocco, Greece, and Italy. Labour-intensive harvesting, mainly by hand, characterises its production and offers substantial employment opportunities in cultivating areas. However, traditional saffron-producing countries such as Spain, Italy, and Greece have witnessed declining production due to labour demands and competition from low-wage countries. Mechanization remains unfeasible due to the delicate nature of the plant. To revitalise saffron cultivation, efforts have been focused on reducing labour costs, improving productivity, and improving quality through innovative techniques, such as soilless crops. In this study, the productivity and quality of saffron was evaluated in a soilless culture and three fertigation doses were evaluated: a control, consisting of Sonneveld and Voogt’s standard nutrient solution, and two treatments with two supplemented solutions, 30% K and 30% Ca. The results indicated that the solution with 30% K obtained higher corm productivity, as well as better quality saffron, as all the products of this treatment were included in Category I according to the ISO 3632 standard, while the quality of saffron grown with the control solution was lower.

Growing Salicornia europaea L. with Saline Hydroponic or Aquaculture Wastewater

Among halophyte plants, Salicornia species (also known as glasswort or sea asparagus) are increasingly grown in open fields and greenhouses for edible or non-edible purposes. Their salinity tolerance makes it possible to irrigate Salicornia plants with saline waters and even seawater, which cannot be used by other crop species. In this work, S. europaea (L.) was cultivated in pots under the typical climatic conditions of the fall season in the Mediterranean region and irrigated with non-saline standard nutrient solution (SNS) or saline wastewater discharged from a greenhouse semi-closed hydroponic (substrate) culture of tomato or a saltwater recirculating aquaculture system (RAS) with Gilthead sea bream (Spaurus aurata L., which was used as such or after dilution (50:50) with SNS. Plant growth was not significantly affected by the composition of irrigation water, while higher antioxidant capacity (measured using the DPPH assay) and concentration of photosynthetic pigments, phenols, flavonoids, and ascorbic acid were found in the shoots of SNS plants than in those of plants irrigated with wastewater. The level of lipid peroxidation and H2O2 production significantly increased in the SNS plants, which also showed higher activity of superoxide dismutase and lower activity of catalase. These results suggest that S. europaea can be cultivated using wastewater with moderate to high salinity discharged from greenhouse hydroponic crops or RASs, and that salt is not strictly required for the growth of this species. Using non-saline nutrient solution can result in moderate oxidative stress that improves the shoot quality of S. europaea.

Efluente da piscicultura e tempos de recirculação nas trocas gasosas e nutrição do agrião hidropônico

ABSTRACT The present study evaluated the potential use of fish farming effluent incorporated into the standard nutrient solution and recirculation time on gas exchange and macro and micronutrient contents of watercress in a hydroponic system. The study was conducted in randomized blocks, in a split-plot scheme with 4 replicates, in two experiments carried out in spring and summer seasons. Plots were composed of different proportions of nutrient solution (NS) and fish farming effluent (FFE): S1 (0% NS and 100% FFE), S2 (25% NS and 75% FFE), S3 (50% NS and 50% FFE), S4 (75% NS and 25% FFE), and S5 (100% NS and 0% FFE). Subplots consisted of two solution recirculation times (Time 1 – T1: 15 for 15 min and Time 2 – T2: 15 for 30 min), totaling 40 experimental plots. Net photosynthesis, stomatal conductance, transpiration, substomatal CO2 concentration, SPAD index, and macro and micronutrient contents were evaluated. Net photosynthesis showed a quadratic fit in both cultivation cycles, with maximum values observed with use of 86.0% NS (spring) and 64.9% NS (summer). Leaf N and P contents indicate that the use of approximately 70% NS can be considered satisfactory, as it promoted the highest values of these macronutrients. Using fish farming effluent can enable the production of watercress in hydroponic systems, influencing the nutritional status of the crop.

Cultivo semi-hidropônico de alface crespa fertirrigada com soluções salinas enriquecidas com nitrato de cálcio

ABSTRACT Lettuce is a leafy vegetable sensitive to salinity, and under saline stress conditions it presents nutritional imbalance, mainly in calcium absorption. Thus, the objective was to evaluate the effect of enriching the nutrient solution with calcium nitrate in solutions prepared with saline water in the lettuce crop. A completely randomized design was used, with five treatments and four replicates. The treatments were represented by five nutrient solutions [S1 - standard nutrient solution (SNP); S2 - SNP + NaCl (3.5 dS m-1); S3 - S2 + Ca (NO3)2 (50% = 6.86 mmol L-1); S4 - S2 + Ca(NO3)2 (100% = 9.15 mmol L-1); S5 - S2 + Ca(NO3)2 (150% = 11.43 mmol L-1)] in lettuce from the curly group, cv. Elba. After preparing the nutrient solutions, the solutions had the following electrical conductivities: 1.8 (S1); 4.8 (S2); 5.4 (S3); 6.0 (S4); 6.6 (S5) dS m-1. Variables of growth, nutrition and postharvest quality of lettuce were evaluated. With the exception of stem diameter, number of total leaves, plant pH and vitamin C content, the other variables were affected by the extra addition of Ca(NO3)2 in the nutrient solutions. The lettuce cv Elba grown in coconut fiber is tolerant to the salinity of 4.8 dS m-1 (S2). In conditions where the use of saline water with 3.5 dS m-1 for the preparation of the nutrient solution is unavoidable, the use of extra doses of Ca(NO3)2 in the lettuce crop is not recommended.

The Key Physiological and Biochemical Traits Underlying Common Bean (Phaseolus vulgaris L.) Response to Iron Deficiency, and Related Interrelationships

Iron deficiency is a worldwide nutritional problem affecting crop production. In Tunisia, this mineral disorder hampers the growth and yield of the major crops due to the abundance of calcareous soils that limit iron availability. The common bean is one of these crops suffering from lime-induced iron chlorosis. The exploration of the variability of common bean responses to iron deficiency allows us to screen tolerant cultivars and identify useful traits and indicators for further screening programs. To this end, two common bean cultivars (coco blanc, CB, and coco nain, CN) were cultivated hydroponically in standard nutrient solution (control) or nutrient solution deprived of iron (stressed). Analyses were reported on plant growth, photosynthetic pigments, photosynthesis, iron distribution, H-ATPase, and Fe-chelate reductase (Fe-CR) activities; important indicators were calculated; and convenient correlations were established. Current results demonstrated that iron deficiency stimulated specific symptoms of iron chlorosis on young leaves that were more precocious and severe in CB than CN. Spad index and chlorophyll pigments measurement confirmed these morphological changes and cultivar differences. Net photosynthesis (Pn) showed the same scheme of variation, with a significant decrease in Pn while respecting the previous cultivar’s variability. Plant growth is no exception to this general trend. The biomass decrease was two times higher in CB than CN. Otherwise, this mineral disorder significantly decreased Fe concentration in all plant organs. However, CN accumulated 40% more Fe than CB, resulting from its higher Fe Fe-CR and H-ATPase activities. Our results also demonstrated the close dependence of these metabolic functions on Fe availability in shoots and the strict relationship between Fe-CR and H-ATPase, photosynthesis, and chlorophyll content. Otherwise, CN demonstrated higher efficiency of Fe’s use (FeUE) for the key metabolic functions (photosynthesis, chlorophyll biosynthesis, and plant growth). The relative tolerance of CN as compared to CB was explained by its ability to establish a functional system less vulnerable to iron deficiency that operates effectively under problematic conditions. This system involves metabolic functions in shoots (photosynthesis, chlorophyll biosynthesis, Fe repartition, etc.) and others in roots (H-ATPase, Fe-CR), which are strictly interdependent.

Exploring the linkage between root system architecture and grain iron content in wheat (Triticum aestivum L.)

Iron (Fe) is a vital element that is equally important for plants, animals, and humans. High Fe concentrations in wheat grains have reliance on plant roots, the hidden half of the plant with a role in nutrient mining. Enhanced grain Fe content of wheat can positively mitigate Fe malnutrition in poor populations. In the present study, 100 wheat varieties were studied to identify the root architectural characteristics in relation to grain Fe concentration. Germinated seeds were transplanted in a rhizobox kept in a standard nutrient solution and were harvested 12 days after transplanting. Roots were scanned and the images were processed using smart root software. A total of 12 wheat varieties, which had a vigorous and weak root system architecture (RSA), in combination with higher and lower Fe grain concentrations, were selected using principal component analysis. The uptake and translocation of Fe from root to shoot were determined through a pot experiment conducted for the above-mentioned 12 wheat varieties, with or without Fe fertilizer applied as FeSO4 to the soil. The data obtained from the pot experiment revealed that Dharabi-11 with vigorous RSA exhibited the highest grain Fe concentration (57.20 mg kg−1), low phytate concentration (6.50 mg kg−1), and maximum 1,000 grain weight, whereas Ujala-16 with weaker RSA had the lowest grain Fe concentration (13.33 mg kg−1), highest phytate concentration (9.07 mg kg−1), and lowest 1,000 grain weight. There were also varieties showing higher grain Fe concentrations with weaker RSA and vice versa. Although it is indicated that vigorous RSA leads to high grain Fe concentration, it is not the sole factor in high grain Fe concentration. Nevertheless, the results demonstrate that large genetic diversity is available among indigenous wheat germplasm in terms of grain Fe concentration and RSA. This information may be utilized in the development of new varieties through conventional and marker-assisted breeding programs using RSA traits for Fe biofortification in wheat, leading to the mitigation of Fe malnutrition.

Performance Evaluation of a Cascade Cropping System

Minimum environmental impact and improved resource efficiency is attainable for soilless cascade systems where the nutrient solution drained from a primary (donor) crop is reused to fertigate a secondary (receiver) crop. However, it is not clear whether the nutrient solution drained from the primary crop can completely satisfy the needs of a secondary crop and if the productivity of the secondary crop is compromised. To test this hypothesis, a prototype soilless cascade system was developed and evaluated. To assess the performance of the system in terms of yield, water and nutrient productivity, a tomato crop was used as the primary crop, while lettuce, spinach and parsley were tested as secondary crops under different drainage management strategies. Measurements of plant growth, crop fresh and dry matter production, leaf chlorophyll and nutrient content, and photosynthesis rate were performed in the secondary crops. In addition, the water productivity and nutrient use efficiency for the fertigation of the primary and secondary crops were recorded. The results showed that the yield of the cascade spinach crop increased by up to 14% compared to the control treatment (monoculture of secondary crop fertigated by standard nutrient solution). The yield of the lettuce and parsley crop was not affected by the reuse of the tomato crop drainage solution. The water productivities of the lettuce, spinach and parsley plants fertigated with pure drainage solution were 50%, 30% and 14% higher than in the control treatment, respectively. The nitrogen and phosphorus use efficiency was improved by more than 50% compared to the control treatments.

Effect of high salinity and of priming of non-germinated seeds by UV-C light on photosynthesis of lettuce plants grown in a controlled soilless system.

High salinity results in a decrease in plant photosynthesis and crop productivity. The aim of the present study was to evaluate the effect of UV-C priming treatments of lettuce seeds on photosynthesis of plants grown at high salinity. Non-primed and primed seeds were grown in an hydroponic system, with a standard nutrient solution, either supplemented with 100 mM NaCl (high salinity), or not (control). Considering that leaf and root K+ concentrations remained constant and that chlorophyll fluorescence parameters and root growth were not affected negatively in the high salinity treatment, we conclude that the latter was at the origin of a moderate stress only. A substantial decrease in leaf net photosynthetic assimilation (Anet) was however observed as a consequence of stomatal and non-stomatal limitations in the high salinity treatment. This decrease in Anet translated into a decrease in growth parameters; it may be attributed partially to the high salinity-associated increase in leaf concentration in abscisic acid and decrease in stomatal conductance. Priming by UV-C light resulted in an increase in total photosynthetic electron transport rate and Anet in the leaves of plants grown at high salinity. The increase of the latter translated into a moderate increase in growth parameters. It is hypothesized that the positive effect of UV-C priming on Anet and growth of the aerial part of lettuce plants grown at high salinity, is mainly due to its stimulating effect on leaf concentration in salicylic acid. Even though leaf cytokinins' concentration was higher in plants from primed seeds, maintenance of the cytokinins-to-abscisic acid ratio also supports the idea that UV-C priming resulted in protection of plants exposed to high salinity.

Sustainable Strategies Based on Reused Leachates and Hydrogen Peroxide Supply to Fertigate Cordyline fruticosa var. ‘Red Edge’ Plants

Leachate reuse is a helpful tool that contributes to the sustainability of agricultural systems, but it requires previous disinfection. Hydrogen peroxide can be found among the disinfectants frequently applied in ecological production systems. Moreover, it can improve the oxygenation of the root system. The objective of this work was to study its effect on C. fruticosa plants fertigated with leachates. A split-plot design with six treatments, three without an H2O2 supply (S0) and three with an H2O2 supply dosage at 2% (SH2O2), was arranged: raw leachate from C. lanatus (L100), raw leachate from C. lanatus diluted with tap water until EC of 2.5 dS m−1 (LWD), and raw leachate from C. lanatus diluted with standard nutrient solution until EC of 2.5 dS m−1 (LNSD). The results produced data about the evolution of the nutrient and leachate solutions throughout the cultivation period. Morphological (height, leaf number, leaf area, total fresh weight, relative water status, and dry weight) and physiological (chlorophyll a, chlorophyll b, carotenoids, chlorophyll a+b, and proline) parameters were studied to reveal the plant response. The efficiency of nutrient utilization was higher with the LWD treatment, and water and nitrogen utilization efficiency decreased under the H2O2 supply. In conclusion, the reuse of diluted leachate is advised for nutritionally undemanding crops, such as C. fruticosa; moreover, the H2O2 supply improved tolerance to salinity and enhanced root growth and Red-Green-Blue (RGB) values.

Produção e qualidade de mini melancia submetida ao estresse salino e razões K+/Ca2+

ABSTRACT Nutritional management can be an efficient strategy to mitigate the effects of salinity on fruit production and quality. This study aimed to evaluate the production and quality of fruits of mini watermelon crop, Sugar Baby cultivar, grown in a protected environment, under salt stress and K+/Ca2+ ratios. The study was carried out in a greenhouse, using a randomized block design, 1 + 5 scheme, resulting in six treatments and four replications. Six nutrient solutions were employed, one using low-salinity water, with NaCl (0.5 dS m-1) and standard nutrient solution (S1, control treatment), and the others using salinized water at 5.0 dS m-1 (S2) and extra addition of K (S3 = 50% and S4 = 100%) and Ca (S5 = 50% and S6 = 100%). The production (fruit production, longitudinal and transverse diameter of fruit, rind thickness, pulp firmness) and postharvest quality (soluble solids, vitamin C, titratable acidity, and maturation index), in addition to the variables related to the color of the pulp (lightness, chroma index, and Hue angle) were evaluated. The addition of NaCl reduced fruit production, longitudinal, and transverse diameter of fruit, rind thickness, and vitamin C content. Among saline nutrient solutions, extra addition of 50% K (S3) attenuates the deleterious effects of salt stress on the production variables and vitamin C content. Under salt stress, extra addition of 50% K (S3) and 100% Ca (S6) intensifies the red color of the pulp.

Effect of Salicylic Acid on the Growth and Development of Sweet Pepper (Capsicum annum L.) under Standard and High EC Nutrient Solution in Aeroponic Cultivation

High electrical conductivity (EC) in cultivation systems with the recirculating nutrient solutions can affect plant growth and development. This study aimed to investigate the effect of salicylic acid (SA) on the selected physiological and biochemical parameters of sweet pepper (Capsicum annum L.) growing aeroponically at standard and high concentrations of nutritive solutions. Four experimental variants were tested: (1) plants cultivated under low EC conditions, (2) plants cultivated under low EC conditions and treated with foliar SA, (3) plants cultivated under high EC conditions, (4) plants cultivated under high EC conditions and treated with SA on leaves and roots. The obtained results revealed that exogenous SA, regardless of EC, reduced the formation of fruits with calcium deficiency symptoms. Furthermore, SA helps plants to cope with high EC nutrient stress through an increase in leaf SPAD index, maximum light-adapted chlorophyll fluorescence and PSII viability. Exogenous SA reduced the number of soluble proteins both under low and high EC; however, increased H2O2 content induced a defence mechanism reflected by the upregulation of antioxidant enzyme activity. The results of the study provide valuable information on the role of SA in the alleviation of the harmful effect of salinity under aeroponic cultivation.

Phenotypic Variability for Root Traits in Andean Common Beans Grown with and without Aluminum Stress Conditions

Genetic variation in wild relatives, GenBank accessions, landraces, and cultivars can unlock key alleles for the traits of interest for breeding programs. Breeding programs often utilize different strategies to quantify the source of heritable variation for target traits. One neglected area of study is the root traits of diverse genotypes, and this is especially the case for aluminum toxicity effects on legumes such as the common bean, which is the most used pulse for direct human consumption. This study evaluated 267 genotypes of common bean that were part of the global Andean Diversity Panel (ADP), consisting mainly of genotypes assembled from public and private breeding programs in Africa and North America, as well as elite lines and land races from the USDA. The ADP was evaluated for root traits at the seedling stage in the Tennessee State University (TSU) greenhouse using a hydroponic system with a standard nutrient solution with and without aluminum (Al). The recorded data on the roots per trial were fit to a linear mixed model for the analysis of variance in order to test for the genotype differences. Adjusted means considered replication and blocks within replication as random effects and genotypes as fixed effects. These were then used for Pearson correlation tests and for principal component analysis (PCA), where the first two vectors accounted for 94.5% and 93% of the explained variation under the control and Al-treatment conditions, respectively. Genotypes were clustered based on the morphology of roots in response to Al-toxicity treatment using the Euclidean distance and Ward’s hierarchical agglomerative clustering method, identifying four distinctive groups significant at p < 0.01. The intra-cluster distance was lower than the inter-cluster distances, which indicated a heterogeneous and homogeneous nature between and within clusters, respectively. The results suggest that crossing between accessions from two of the clusters would result in the maximum genetic segregation. One cluster was found to have a higher Al-toxicity tolerance than the others.

Trocas gasosas e produção em couve folha sob concentrações de Ca(NO3)2 em solução nutritiva salinizada

ABSTRACT Adequate mineral supplementation can be a strategy to enable the use of brackish water in the production of vegetables. This study intended to evaluate the effect of calcium nitrate concentrations on leaf gas exchanges and yield of kale (Brassica oleracea L) fertigated with salinized nutrient solutions. The experiment was conducted in a randomized block experimental design (4 + 1), with four replicates. Four nutrient solutions prepared in brackish water (6.0 dS m-1) containing four concentrations of Ca(NO3)2 [(750, 1,125, 1,500, and 1,875 mg L-1)] and a control treatment (standard nutrient solution using low-salinity water, 0.5 dS m-1 (750 mg L-1 of Ca(NO3)2) were used in the study. The following analyses were performed: leaf gas exchanges, leaf area, and fresh matter yield. The standard nutrient solution promoted higher values for photosynthetic rate (13.06 µmol CO2 m-2 s-1), stomatal conductance (0.19 mol H2O m-2 s-1), transpiration (2.76 mmol H2O m-2 s-1), instantaneous water use efficiency (4.73 mmol CO2 mol-1 H2O), instantaneous carboxylation efficiency (0.053 mmol CO2 mol-1 CO2), leaf area (2.78 cm2 per plant), and leaf fresh matter yield (2.64 kg per plant). The Ca(NO3)2 not nullified but mitigated the deleterious effect of salt stress on leaf gas exchanges, except for kale yield (leaf fresh matter).

Light Intensity and Growth Media Influence Growth, Nutrition, and Phytochemical Content in Trachyandra divaricata Kunth

Trachyandra divaricata (Sandkool) is one of the most abundant wild edible inflorescence vegetables in South Africa. The dearth of literature on its edibility, nutrient composition, and conservation has contributed to its underutilisation. This study investigated mineral and proximate content, phytochemical compositions, and growth response of T. divaricata to light intensity and soilless media. Treatments comprised four media (LECA clay, silica sand, peat, and vermiculite) which were subjected to different shade levels (no shade, 20, 40, 60, and 80%) created from a factory-made 20% density net by doubling (40%), tripling (60%), and quadrupling (80%). All treatments were irrigated with a standard nutrient solution. The results showed that the treatments impacted the yield of T. divaricata significantly in terms of biomass and flower buds, especially in plants cultivated in peat under normal greenhouse lighting (no shade). Conversely, plants developed significantly more specific leaf size and total chlorophyll content under shade levels (20, 40, 60, and 80%) in different growth media, even though the values were comparable among treatments. The highest Ca, Mg, Cu, Fe, and Mn levels were consistently recorded in flowers of T. divaricata grown in LECA clay under 80% shade level, while other minerals varied in tested treatments. The peat medium under 20% shade optimised the neutral detergent fibre (NDF) and acid detergent fibre (ADF) content of the flowers, whereas both fat and protein contents were greatly enhanced by peat and vermiculite, respectively, under the 80% shade. Consistently, the lowest phytochemical contents were recorded in LECA clay subjected to 80% shade, whereas the highest polyphenols and DPPH antioxidants were produced by silica sand medium treated with 20% shade. Both TEAC and FRAP antioxidants were improved significantly in LECA clay under no shade and the 60% shade level. However, both 20% and 60% shade levels enhanced the flavonol content significantly. On the basis of these findings, T. divaricata is a promising inflorescent vegetable that may be considered for domestication and further research due to its potential pharmacological and nutraceutical values.

Effect of moderate salinity on Golden Thistle (Scolymus hispanicus L.) grown in a soilless cropping system

• Soilless cultivation of S. hispanicus l. improved plant growth and yield characteristics. • S. hispanicus L. was resilient to moderate salinity until 90 days after transplant. • Salinity level of 10.0 and 15.0 mM improved functional quality characteristics. • Physiological indicators significantly declined at salinity levels of 10 and 15 mM NaCl. Selecting salt-tolerant crop species for cultivation might be a feasible option to maintain crop productivity in arable lands affected by salinity. In this context, here we examine the responses of the wild edible green golden thistle ( Scolymus hispanicus L.) to moderate levels of salinity when grown in a soilless system for culinary use. Treatments were obtained by establishing four NaCl concentrations (0.5, 5.0, 10.0, and 15.0 mM) in a standard nutrient solution, resulting in initial solution electrical conductivities (EC) of 2.2, 2.8, 3.2, and 3.8 dS m − 1 , respectively. By the end of the experiment, 120 days after transplanting (DAT) drainage EC reached 2.65, 3.33, 3.96, and 4.51 dS m − 1 , respectively. At the first harvest, 90 DAT, the increase of the NaCl concentration had no significant impact on the number of leaves per plant, leaf fresh and dry weight [g plant −1 ], and root dry weight [g plant −1 ]. At the second harvest (120 DAT), 15.0 mM NaCl significantly decreased root and leaf fresh and dry weight without affecting the number of leaves per plant compared to 0.5 and 5.0 mM NaCl, while 10 mM NaCl had no impact on any of these parameters. The concentrations of K + , Ca 2+ , Mg 2+ , and P in the leaves were not influenced by the tested salinity levels, while those of organic-N and NO 3 − -N were significantly reduced by 10 and 15 mM NaCl, 90 DAT. Furthermore, 10 and 15 mM NaCl significantly increased the Cl − and Na + concentrations in leaves, but not in the roots. In the root tissues, only the K concentration was reduced by salinity while P increased at the highest salinity level (15 mM NaCl). Based on these results, we conclude that S. hispanicus L. is resilient to moderate salinity levels and can be considered a promising candidate plant for introduction to soilless cropping systems.

Sweet basil can be grown hydroponically at low phosphorus and high sodium chloride concentration: Effect on plant and nutrient solution management

Agronomic inputs in agriculture easily exceed crop needs causing environment pollution. Phosphorus (P) is a macronutrient largely used in agriculture as a mineral fertilizer that requires an accurate management because it is a finite and non-renewable resource. Growing plants hydroponically can optimize plant nutrition achieving high crop nutrient use efficiency. However, irrigation water of poor quality (saline) interferes with crop performance. In this study, the effects of different P and NaCl levels in the root zone were evaluated on basil plants grown in a deep liquid culture system in a growth chamber. Two experiments with different P (from 0.1 to 1.0 mol m−3) and NaCl (from 0 to 60 mol m−3) concentrations in the nutrient solution were carried out. Plant growth, leaf gas exchanges and fluorescence, uptake of minerals and water, and leaf quality (content of minerals and pigments, and antioxidant capacity) were analysed. The most relevant morphological plant response to the low P (i.e., roughly 0.1 x of a standard nutrient solution) concentration consisted in a greater root/shoot ratio. However, plants growing at low P concentration did not show any reduction in yield and quality. Sodium chloride did not significantly affect plants yield and quality up to a concentration of 30 mol m−3 confirming the tolerance of basil to moderate saline stress. Significant reduction in the total biomass, water uptake and photosynthesis instead occurred at NaCl 60 mol m−3. These results confirmed the hypotheses that basil can be grown hydroponically at low P and high NaCl concentration with proper management of the nutrient solution. The absence of significant interactions between P and NaCl suggests that these two factors can be managed independently with potential benefits for crop economic and environmental sustainability.