Salinity is one of the most limiting abiotic stresses in the global agricultural sector. The objective of this study was to evaluate the effect of irrigation water salinity on the initial development ...of P. edulis Sims. seedlings propagated by seeds, grafting and cuttings. Treatments were distributed in a completely randomized design, in a 5 x 3 factorial arrangement, corresponding to 5 levels of irrigation water electrical conductivity (0.3 - control, 1.8, 3.3, 4.8, and 6.3 dS m-1) and 3 propagation methods (seeds, cuttings and grafting), with four replicates and one plant per plot. Fifty days after the imposition of treatments with saline water, plant height, number of leaves, stem diameter, total chlorophyll, stomatal conductance, relative leaf water content, total water consumption, dry matter of root, shoot and total, root length and root volume were evaluated. The increase in water salinity affected with greater intensity the growth and development variables (height, total dry matter and root volume of the plant) and the physiological characteristics (stomatal conductance) of the species Passiflora edulis, regardless of the method of propagation. Seedlings propagated by grafting showed better development compared to the other propagation methods (seeds and cuttings). The interaction between the propagation methods and water salinity affected seedlings propagated by seeds and cuttings with greater intensity.
Salinity is one of the striking problems in agricultural production in many parts of the world. Seed germination and seedling growth are two critical stages for the establishment of crops generally ...most sensitive to salt stress. The present study aimed at evaluating the germination and initial growth of pepper seedlings produced from seeds under different soaking times in NaCl solutions. The experiment was carried out in a completely randomized design, in a 2 × 4 × 5 factorial scheme using two pepper species (Capsicum chinense Jacq. and Capsicum frutescens L.), four levels of electrical conductivity (EC) of solutions (1.5, 3.0, 4.5, and 6.0 dS m-1) and five times of seed soaking in the solutions (2, 4, 6, 8 and 10 h), with three replications. The traits evaluated were the number of germinated seedlings, percentage of germination, seedling height, and root length. The results showed that C. frutescens pepper was more tolerant to different times of soaking in saline solutions prepared with NaCl compared to C. chinense. Thus, the results suggest that depending on the pepper species, it is recommended to use seeds primed in saline solutions with salinity levels compatible with those under field conditions (in saline soils and/or irrigation with saline waters).
•Electrical conductivity of soil is relevant for monitoring salt-affected soils.•Six soil solution extraction methods were tested for five different soils.•The soils had differing mineralogical ...assemblages and textures.•Centrifugation, porous capsule and soil:water extracts were related to saturated paste extracts.•Fourty-eight equations were developed for the methods tested.
Characterization of the soil solution is of fundamental importance for monitoring plant nutrient availability, environmental contamination, and evaluation of salt-affected soils. Due to the diversity of methodologies adopted in various parts of the world, comparison of the most common extraction methods in different types of soils is warranted. This study compared the efficiency of five soil solution extraction methods for five soils with different mineralogical assemblages and textures with the most commonly used saturated paste extract method. The extraction methods compared were: centrifugation, porous extractor capsules, and soil–water extracts (soil:water ratio of 1:2, 1:5, or 1:10). The soil types evaluated were: Regosol, Luvisol, Gleysol, Nitisol and Ferrosol in the soil surface and subsurface horizons. Linear regression equations were developed that allowed accurate estimation of electrical conductivity of the saturated paste extract (ECse). Ten equations were developed for the porous capsule method, eight were developed for the centrifugation method (with the exception of the Regosol with 900 g k−1 of total sand, which was not suitable for this method due to the high sand content), and 30 equations were developed for the soil–water extract method (at each of the soil:water ratios tested). The diversity of equations developed for soils with different mineralogical assemblages and textures should assist growers and extension workers who need to know the soil electrical conductivity for making soil management decisions.
ABSTRACT The occurrence of water sources with high concentrations of salts is a common problem in the semi-arid region of north-eastern Brazil. The search for management strategies that can minimize ...the effect of salt stress on crops is therefore extremely important. As such, this study aimed to evaluate gas exchange and production in the yellow passion fruit ‘BRS GA1’as a function of irrigation strategies using brackish water and doses of potassium. The research was carried out under field conditions in São Domingos, in the state of Paraíba, Brazil, using a randomized block design in a 6 × 2 factorial scheme, with treatments comprising six irrigation strategies using water (irrigation with low-salinity water throughout the cycle – WS; irrigation with high-salinity water during the vegetative stage – VE; during the flowering stage – FL; the fruiting stage – FR; during successive vegetative/flowering stages - VE/FL; successive vegetative/fruiting stages - VE/FR) and two doses of potassium (60% and 100% of the recommended dose of 345 g K2O per plant per year), with four replications and three plants per plot. Two levels of water salinity (1.3 and 4.0 dS m−1) were used during different phenological stages of the crop. Irrigation with water at 4.0 dS m−1 reduced the leaf water potential, leaf osmotic potential, stomatal conductance, transpiration, and rate of CO2 assimilation of the yellow passion fruit, regardless of the irrigation strategy. The continuous salt stress during the vegetative and flowering stages compromised production in the yellow passion fruit.low-salinity water throughout the cycle – WS; irrigation with high-salinity water during the vegetative stage – VE; during the flowering stage – FL; the fruiting stage – FR; during successive vegetative/flowering stages - VE/FL; successive vegetative/fruiting stages - VE/FR) and two doses of potassium (60% and 100% of the recommended dose of 345 g K2O per plant per year), with four replications and three plants per plot. Two levels of water salinity (1.3 and 4.0 dS m−1) were used during different phenological stages of the crop. Irrigation with water at 4.0 dS m−1 reduced the leaf water potential, leaf osmotic potential, stomatal conductance, transpiration, and rate of CO2 assimilation of the yellow passion fruit, regardless of the irrigation strategy. The continuous salt stress during the vegetative and flowering stages compromised production in the yellow passion fruit.
ABSTRACT The use of substances that can mitigate the harmful effects of salt stress is a promising alternative for the use of saline water, especially in semi-arid regions. The aim of this study was ...to evaluate the effect of different concentrations of hydrogen peroxide in mitigating salt stress in the mini watermelon grown in a hydroponic system. The study was carried out in a greenhouse, in an area belonging to the Federal University of Campina Grande, Pombal, Paraíba. The experimental design was completely randomised using a split-plot factorial scheme with four levels of electrical conductivity for the nutrient solution-ECns (2.1, 3.1, 4.1, and 5.1 dS m-1) considered the plots, and four concentrations of hydrogen peroxide-H2O2 (0, 20, 40, and 60 μM) the subplots, with five replications. The foliar application of hydrogen peroxide in concentrations of between 17 and 20 µM mitigated the effects of salt stress on stomatal conductance, the rate of CO2 assimilation, carboxylation efficiency, and carotenoid content in the mini watermelon up to an ECns of 5.1 dS m-1. Foliar application of hydrogen peroxide in concentrations greater than 20 µM intensified the effects of salt stress on gas exchange and the synthesis of photosynthetic pigments in the mini watermelon. Furthermore, there was an increase in electrolyte leakage in the leaf blade.
The objective was to evaluate the water consumption of sunflower cultivars irrigated with saline waters. The experimental design utilized was in randomized blocks of a 2 x 4 factorial arrangement. ...This was composed of two levels of electrical conductivity (ECw) of irrigation water (N1 - 0.6 and N2 - 3.0 dS m-1 at 25 ºC) and four cultivars of sunflower (C1 - Helio 863, C2 - Embrapa 122-V2000, C3 - Catissol 01 and C4 - Multissol), with three replications, each of them with three plants totaling 72 experimental units. There was a reduction in water consumption of sunflower cultivars irrigated with saline water (N2 - 3.0 dS m-1). The irrigation with saline water resulted in a greater volume of drained water in all sunflower cultivars.
Guava is a popular Brazilian fruit that is widely produced in Northeastern Brazil, a region with water sources that commonly have high concentrations of salts. Thus, searching for techniques that ...allow the management of these waters is extremely important for the expansion of irrigated agriculture. In this context, salicylic acid is a phytohormone that can contribute to reducing the effects of salt stress on plants. Given the above, this study evaluated the effect of foliar application of salicylic acid at different concentrations in the mitigation of salt stress on gas exchange, growth, and quality of 'Paluma' guava seedlings. The experiment was conducted in a greenhouse, in Campina Grande - PB, Brazil, using a randomized block design in a 5 × 5 factorial arrangement, corresponding to five levels of electrical conductivity of water (0.6, 1.5, 2.4, 3.3, and 4.2 dS m-1) and five concentrations of salicylic acid (0 - Control; 0.8, 1.6, 2.4, and 3.2 mM), with four replicates and two plants per plot. Foliar application of salicylic acid at a concentration of up to 1.4 mM reduced the deleterious effects of salt stress on the instantaneous water use efficiency of 'Paluma' guava seedlings at 180 days after sowing. The concentrations of salicylic acid applied via foliar did not mitigate the harmful effects of irrigation water salinity on the growth and quality of 'Paluma' guava seedlings.
Keywords: Abiotic stress, Psidium guajava L., water scarcity.
Supplemental irrigation during dry spells could reduce maize yield losses in tropical semi-arid regions, notably in small farms. However, good quality water reserves are not sufficient to meet the ...demands of farming communities. Consequently, our objective was to evaluate the productivity and profitability of maize under different simulated rainfall scenarios, with and without supplemental irrigation (SI) with brackish water. The field experiments were carried out during the cropping seasons of 2018 and 2019 on Ultisol. The experiment followed a randomized block design in the split-plot scheme with four replicates. The plots were formed by simulating the water supply in the soil corresponding to four water scenarios (rainy, normal, drought and severe drought), and the sub-plots with or without SI with brackish water (Electrical conductivity of 4.5 dS m−1). Mean yields of green maize ears were 13,083, 11,532, 10,358 and 9,609 kg ha−1 for rainy, normal, drought and severe drought scenarios, as supplemented with brackish water. For the same treatments without SI the values were 11,394, 7,896, 3,913 and 1,374 kg ha−1, respectively. Data on farmer's income showed that under normal, drought and severe drought supplementation with brackish water becomes economically advantageous from 0.9, 1.0 and 2.4 ha, respectively, while maize cultivation without SI is not advantageous under the last two scenarios. For severe drought conditions, however, SI using brackish water reduced commercial yield by 27 % with negative effects on the farmers’ profitability. In this case, it is necessary to use water with either lower salinity or select salt tolerant crops.
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