Salinity Levels Of Irrigation Water Research Articles

Sugarcane (Saccharum officinarum L.) under saline stress: Growth, productivity, technological quality, and industrial yield

Water scarcity is one of the main factors that contribute to the reduction of productivity in crops, and irrigation with lower water quality is an option to minimize water stress. The objective of this work was to evaluate the growth, productivity, technological quality, and industrial yield of the plant sugarcane and the first ratoon irrigated with brackish water and leaching conditions and the productivity of the second ratoon under the rainfed regime. The research was carried out at the Federal Rural University of Pernambuco, Recife-PE, in drainage lysimeters using a completely randomized design, in a 5 × 2 factorial scheme: five levels of irrigation water salinity (ECw: 0.5, 2.0, 4.0, 6.0, and 8.0 dS m −1 ) obtained by adding NaCl and CaCl 2 to the local distribution water (0.5 dS m −1 ) and conditions without leaching fraction (LF1 = 0) and with leaching fraction (LF2 = 0.17), corresponding to 100 % and 120 % of the crop evapotranspiration , with four replications. The growth, productivity, and technological quality were measured in the plant and first ratoon cane and the productivity of the second ratoon. The salinity of the irrigation water reduced the growth, productivity, technological quality, and industrial yield in the plant sugarcane and first ratoon; this effect is minimized by the leaching fraction of 0.17. The salinity of irrigation water from plant sugarcane and the first ratoon promoted a residual effect , negatively affecting the agronomic performance of the second ratoon. • Salinity reduces growth, yield, technological quality, and industrial yield in sugarcane plants. • Salinity of 8 dS m −1 promotes an average yield reduction of up to 43 % in the condition without leaching fraction. • The use of the leaching fraction (0.17) promotes a yield greater than 25 % compared to the condition without leaching. • Sugarcane is classified as moderately salinity tolerant when the leaching fraction (0.17) is adopted.

An assessment of domestic sewage sludge in pearl millet-wheat system under saline irrigation

The present two-year experiment (2017-19) evaluated the impact of domestic sewage sludge (SS) on yield parameters and soil nutrient status under the pearl millet-wheat system using saline irrigation. The field study consisted of three irrigation treatments [canal water (0.35 dS/m); saline water (8 and 10 dS/m)], and five fertilizer treatments [control, SS (5 t/ha), SS (5 t/ha)+50% recommended dose of fertilizers (RDF), SS (5 t/ha)+75% RDF and 100% RDF]. The results revealed a significant reduction in the biological yield and yield attributes, and protein content of both crops with increasing salinity levels of irrigation water during both the years. However, all these parameters recorded significantly highest values under 100% RDF which was statistically at par with SS (5 t/ha) + 75% RDF treatment. The soil available sulphur (S) was significantly increased with 8 and 10 dS/m EC of saline water over canal water (0.35 dS/m) irrigation. But, SS (5 t/ha) + 75% RDF obtained 36.7 and 22.3% higher available S over control and 100% RDF, respectively. No significant effects were made in DTPA-extractable micronutrients (Fe, Mn, and Cu) with saline irrigation except Zn, which was reduced under saline environment. SS added treatments obtained higher micronutrient concentration over control. Hence, SS incorporation has proven useful in sustainable crop production and improved micronutrient availability in the soil.

Biochar Amendment Combined with Straw Mulching Increases Winter Wheat Yield by Optimizing Soil Water-Salt Condition under Saline Irrigation

The freshwater deficit is the major constraint to winter wheat production. Saline water irrigation could alleviate wheat water stress while increasing the risk of soil salinization, which would result in wheat yield reduction due to additional salt stress. The objective of the present study is to explore the effect of a straw-returning mode to promote winter wheat production under saline water irrigation. A field experiment was conducted during the winter wheat growing seasons of 2017–2018 and 2018–2019. Four returning modes were set, based on an equivalent carbon input: straw mulching (SM), biochar amendment (BA), straw mulching combined with biochar amendment (SM+BA), and the control without straw-returning (CK), along with three salinity levels of irrigation water: 0.47 dS m−1 (I0, freshwater), 3.25 dS m−1 (I1), and 6.75 dS m−1 (I2). Saline water irrigation alone triggered soil salt accumulation and reduced the wheat grain yield by 9.43––18.19%. Returning straw to fields increased soil organic carbon content by 16.41––52.21% and decreased soil bulk density by 0.69––1.46%. The highest increase in wheat grain yield (16.60––21.80%) was always obtained when using treatment SM+BA, due to the increased soil moisture content (3.15––12.31%) and lower salt levels (24.79––44.29%) compared to CK. The results of the present study established that SM+BA provided better soil water–salt conditions and nutrient environment for winter wheat growth than a single treatment. Thus, the combined application of SM and BA was shown to be a proper mitigating strategy to cope with the adverse effects of saline irrigation on winter wheat production and to promote the sustainable use of saline water irrigation.

The optimal irrigation water salinity and salt component for high-yield and good-quality of tomato in Ningxia

Although saline water can be used as an alternative of freshwater resources for agricultural irrigation, especially in arid and semiarid areas, however, unsuitable saline water quality and unreasonable irrigation technology may result in the detrimental effects on plant growth, yield and quality of products. Thus, a three-year open field experiment was conducted in Ningxia to investigate the influence of three irrigation water salinity levels (1, 2 and 3 g/L) and five molar concentration ratios (MCR) of Na:Ca (1, 3, 5, 7 and 9) on processing tomato planting, in terms of crop water consumption, tomato yield traits and fruit quality characteristics. The results are as follow: (i) The water consumption decreased significantly with the increasing irrigation water salinity and MCR of Na:Ca. (ii) With the increase of irrigation water MCR of Na:Ca, both the average fruit weight, marketable yield and total yield decreased linearly, as well, the ratio of marketable yield to total yield decreased. Additionally, irrigation water with higher salinity (2 g/L and 3 g/L) and lower MCR of Na:Ca (1 and 3) was more conducive to root water uptake and average fruit weight accumulation, than that with lower salinity and higher MCR of Na:Ca. (iii) With irrigation water salinity of 1 g/L and 2 g/L, both the vitamin C, lycopene, fructose, sucrose and starch content of tomato fruit have quadratic function relationship with the irrigation water MCR of Na:Ca. Moreover, the threshold of irrigation water MCR of Na:Ca for soluble solids, lycopene and starch accumulation was 7, while the content of total soluble sugar, fructose and sucrose achieved the maximum value as the MCR of Na:Ca arrived 5. (iv) With irrigation water salinity of 3 g/L, the total soluble sugar and glucose of fruit decreased with the increase of irrigation water MCR of Na:Ca, especially, the fruit fructose, sucrose and starch concentration decreased linearly, furthermore, the threshold of irrigation water MCR of Na:Ca for vitamin C and soluble solids accumulation was 5. Synthetically, saline water with salt content of 2 g/L and MCR of Na:Ca at 5 was optimal in the present study for mulched drip irrigation on tomato cultivation in the northern Yinchuan plain of Ningxia, obtaining the relatively high-yield (9.72 ×104 kg/hm2) and good-quality of tomato.

Reducing Water Salinity at Flowering Stage Decreases Days to Flowering and Promotes Plant Growth and Yield in Chile Pepper

Water scarcity is a major problem for crop production around the world including Southwestern United States and growers are increasingly using groundwater for agriculture in Southern New Mexico. Most of the groundwater in New Mexico is brackish and continuous long-term use could lead to salt accumulation in the soil. Reverse osmosis (RO) can desalinate brackish groundwater (BGW), however, environmentally safe disposal of RO concentrate is costly. This greenhouse study evaluated the effects of BGW and RO concentrate at various growth stages of two chile pepper cultivars, NuMex Joe E. Parker and NuMex Sandia Select. Five salinity treatments were applied to plants, three of them used saline waters of 0.6 (control), 4.0 (BGW), and 8.0 dS/m (RO) throughout the growing season, whereas the other two changed waters of 4.0 and 8.0 dS/m to waters of 2.0 and 6.0 dS/m from the beginning of the flowering stage. Number of flowers, days to flowering, relative plant heights, relative fresh biomass, fruit yields, photosynthetic rate (Pn), stomatal conductivity (gS), and actual evapotranspiration (ETa) significantly decreased with increasing irrigation water salinity levels. Concentrations of Mg2+, Na+, and Cl− in plants increased with increasing water salinity levels. Changing to irrigation with reduced salinity waters of 2.0 and 6.0 dS/m at the flowering stage initiated reproductive development more rapidly and alleviated the adverse influence of salinity on the number of flowers of chile pepper, plant height, Pn, as well as fresh shoot and fruit weight than that with continuous irrigation with electrical conductivity (EC) of 4.0 dS/m and 8.0 dS/m beyond the flowering stage. Irrigation that practices a change from high salinity to lower salinity at the flowering stage can optimize the use of saline irrigation water for growing chile peppers.

Modeling Soil Profile Salinity with HYDRUS-1D

Salt accumulation within the root zone significantly effects plant growth and development in arid and semi-arid regions. Today, use of low-quality irrigation water in agricultural production is increasing rapidly, because of continuous depletion and pollution of water resources. This means more salt transferred to the soil profile. It is of great importance to predetermine the effects of irrigation practices for sustainable crop production. For this purpose, models and tools that can produce reliable and fast results should be used. In this study, soil profile salinity was modeled with the HYDRUS-1D software. In present study, Three different irrigation water salinity levels (S1=0.25 – control/municipal tap water, S2=1.5, S3=3.0 dS m-1) and 4 different irrigation volumes (leaching ratio) (LR1=10%, LR2= 20%, LR3=35%, LR4=50%) were modeled in a randomized plots factorial experimental design with 3 replications. Each treatment was carried out in individual PVC lysimeters with a length of 115 cm and a diameter of 40 cm in open-field to determine the efficiency of the model at different salinity levels and leaching rates. Alfalfa (Medicago sativa L.) was preferred as a plant due to its economic value, effective root depth and being a perennial plant. During the growing period, a total of 7 irrigations were practiced and five soil samples were taken from 20, 40, 60, 80 and 100 cm depths at the last day of each month. Present findings revealed that values modeled with the HYDRUS-1D software were sufficient to determine the soil profile salinity. Relative error values (RE) ranged from 0.048 to 0.307. Increase in salinity and irrigation applications reduced the accuracy of the model. However, it can be said that the values produced by the model were sufficient even under the mentioned conditions. Especially for academic studies, the HYDRUS-1D software can be used to obtain fast and reliable results.

Assessment of irrigation water salinity effects on red beet under Mediterranean conditions

Plant tolerance to salinity stress is vital for irrigation scheduling, decision-making, planning and operation, and most critically, water resource management. Although there are numerous scientific data on the response of various plants to salinity stress, there are few studies on red beet in the literature, and specifically under Mediterranean conditions. This study aimed to investigate the effects of water salinity stress on water use, growth, yield parameters, and salinity threshold and slope values of red beet in Mediterranean conditions. In addition to control (0.6 dS m-1), five irrigation water salinity levels including low (1.5 dS m-1), medium-low (3.0 dS m-1), medium (4.5 dS m-1), medium-high (6.0 dS m-1) and high salinity (8.0 dS m-1) stresses were used as treatments. Increased water salinities caused increases in electrical conductivity and pH values of saturated soil paste extracts and drainage waters, while decreases in water use affected plant height storage root yield and water use efficiency. The salinity threshold and slope values of red beet were determined as 3.10 dS m-1 and 4.42% per dS m-1.

Effects of ridge planting on crop seedlings under saline water drip irrigation

AbstractA field experiment was conducted in northwest China to study the effects of different irrigation water salinity levels on the emergence and growth of corn, sunflower, summer squash, and cowpea. Two tillage systems (flat and ridge planting) and five salinity levels (at 1.7, 4.0, 6.3, 8.6, and 10.9 dS/m) were tested. Compared with flat planting, the soil salinity within 30 cm horizontally from the drip tapes decreased by 15% in the ridge planting system. Ridge planting significantly improved the emergence and growth of crops, which was mainly manifested in higher emergence rates, reduced emergence time, and increased dry biomass, especially under high‐salinity conditions (electrical conductivity of irrigation water >4 dS/m). The electrolytic conductivity of the saturation extract threshold at which corn, sunflower, summer squash, and cowpea endured without reduced emergence rates was 5.8, 5.8, 4.8, and 4.0 dS/m, respectively. Above this threshold, the relative emergence rate decreased by 11%, 16%, 14%, and 20%, respectively. Our results indicate the agronomic benefits of ridge planting, and the soil environment was improved by ridge planting with saline water drip irrigation. In addition, we discuss the crop responses in terms of emergence rates and relative seedling dry biomass in relation to soil salinity. Suggestions for the secure and efficient use of saline water for irrigation in arid regions have been put forward.

Modeling response of spring wheat yield to soil water and salt contents and its application in scheduling brackish water irrigation

Fresh water shortage and soil salinization are two key factors restricting agricultural development in arid areas. Brackish water is a possible alternative resource for crop irrigation, but brackish water irrigation should be properly scheduled to balance crop yield increment and soil salinization control. To determine suitable water amounts for crop irrigation under different water salinities, an agro-hydrological model, LAWSTAC, was used to simulate soil water and salt dynamics and crop growth in salinized croplands in an arid region of Northwest China. Model calibration and validation results of soil water content, salt concentration, groundwater table depth, leaf area index, biomass, and crop yield agreed well with the field measurements of spring wheat (Triticum aestivum L.) under both fresh and brackish water irrigations with the Nash and Sutcliffe efficiency of 0.50–0.96 and the coefficient of determination of 0.55–0.98. The model was further used to simulate crop yields for 432 combinations of six irrigation levels, six irrigation water salinity levels, four initial groundwater table depths, and three initial soil salt concentrations. Based on the simulation results, a function of relative crop yield response to soil water content and salt concentration was developed, which is expressed as the product of a hyperbolic function for water stress and a sigmoid function for salt stress. For known initial soil water content and salt concentration, a procedure was proposed to determine suitable water amounts applied to the cropland under different irrigation water salinities for expected crop yields using the developed crop-water-salinity production function. With the procedure, the minimum amount of applied water with known salinity can be obtained for an expected relative crop yield. The results are helpful to the amount control in fresh or brackish water irrigations for sustainable crop production in salinized croplands.

Productive characteristics of sunflower genotypes irrigated with different levels of saline water

Sunflower is suitable for family farmers from Northeast Brazil who are benefited by the production of grain and oil and is adequate for crop rotation and for honey production. The need for irrigation in this region leads to the realization of this study for evaluating the production components of four sunflower genotypes irrigated with different levels of water salinity. The study was carried out in the municipality of Remigio, Paraíba, Brazil, using a randomized block with split plots experimental design in a 5 x 4 factorial arrangement. Treatments consisted of five electrical conductivity levels of the irrigation water at 25 °C (L1 - 0.14 (reservoir water), L2 - 1.50, L3 - 2.50, L4 - 3.50, and L5 - 4.50 dS m- 1), and four sunflower genotypes (C1 - Embrapa 122-V2000, C2 - Olisun 03, C3 - AG 963, and C4 - Multissol) with three replicates. The irrigation water salinity levels tested did not influence the variables studied. Different values of the variables among sunflower genotypes were due to characteristics inherent to each genotype. Sunflower genotype Olisun 03 presented the highest oil content, while the lowest content was observed in Multissol.

Ensemble HYDRUS-2D modeling to improve apparent electrical conductivity sensing of soil salinity under drip irrigation

Monitoring and mapping soil salinity are valuable for irrigation management and reclamation of salt-affected agricultural soils in arid and semi-arid regions. Proximal measurements of apparent soil electrical conductivity (ECa) can help characterize soil salinity spatial distributions. However, ECa is not solely a function of salinity. ECa is strongly influenced by soil salinity, water content, and edaphic properties such as texture and bulk density. Consequently, monitoring and mapping salinity based on geospatial ECa measurements is challenging in fields with dynamic and spatially complex patterns of salinity and water content, such as occurs under drip irrigation. We conducted a numerical modeling study to evaluate protocols for using proximal ECa sensing in drip irrigated systems, focusing specifically on the measurement distance from the drip-line that consistently identifies areas of high salinity in the rootzone. The measurement distance was evaluated as a function of six irrigation management parameters: soil hydraulic conductivity, irrigation discharge, irrigation interval, solute concentration, root-zone volume, and leaching fraction. HYDRUS-2D was used to run a 729 member ensemble of drip irrigation simulations of water and solute dynamics under different irrigation management scenarios. Two case studies were simulated for clay loam soil: (1) low salinity soil irrigated with high salinity irrigation water and (2) high salinity soil irrigated with low salinity water. Depth-averaged ECa measurements down to the 75 and 150 cm depths, such as can be obtained using an electromagnetic induction (EMI) sensor, were evaluated in the simulations. According to the ensemble results, a reliable EMI measurement distance from the drip-line was about 100 cm for the case of low salinity irrigation in saline soil and adjacent to the drip-line for the high salinity irrigation. The ensemble ECa and EC of saturated paste extract (ECe) distributions were twice as sensitive to the irrigation water salinity level as compared to the other irrigation management parameters. The probabilistic ensemble approach can be extended to a variety of case studies to aid soil scientists and agricultural consultants monitoring and mapping soil salinity with ECa-directed soil sampling for micro-irrigation systems.

Response of Potted Hebe andersonii to Salinity under an Efficient Irrigation Management

Although the use of marginal-quality water can be an effective measure to alleviate water scarcity, it often contains a high concentration of salts that can compromise crop growth. As a result, farmers apply more water than necessary to leach salts away from the root zone, resulting in wasted water and the release of fertilizers into the groundwater. In this study, we assessed the effects of three salinity levels of irrigation water (1.8 dS m−1, 3.3 dS m−1, and 4.9 dS m−1) on the physiology and ornamental traits of Hebe andersonii cv. Variegata. The experiment was carried out with potted plants in a greenhouse for seven months. We also studied the feasibility of growing this cultivar without leaching salts. The results showed that Hebe plants can be grown without leaching using water up to 3 dS m−1. This setup produces plants with high water use efficiency and without reducing their ornamental value. Meanwhile, irrigation with 5 dS m−1 water reduced the quality of Hebe but did not compromise its physiological processes. The photosynthesis of Hebe under salinity conditions was mainly controlled by stomata, which was related to the level of salt stress and water status of the plant. Salinity had no significant effects on photosystem II, which can be explained by the fact that Hebe was able to dissipate the excess excitation energy as heat effectively. Hebe was able to avoid ion toxicity and maintain a suitable nutrient balance under the salinity levels tested in this experiment.

Photosynthetic Responses, Growth, Production, and Tolerance of Traditional Varieties of Cowpea under Salt Stress.

HighlightsSalinity tolerance among traditional varieties of cowpea is variable.High net photosynthesis is observed in cowpea-tolerant varieties under salt stress.The decrease in photosynthesis is caused by stomatal restriction and low photochemical efficiency.Cowpea varieties are similar in photochemical efficiency and photochemical quenching.The decrease in pod number and seeds per pod are the main effects of salinity on cowpea production.Cowpea is the main subsistence crop—protein source—for the Brazilian semi-arid region. The use of salt-stress-tolerant varieties can improve crop yields. We evaluated the effect of irrigation with brackish water on the growth, photosynthetic responses, production, and tolerance of fifteen traditional varieties of cowpea. The experiment was conducted in randomized blocks, in a 15 × 2 factorial scheme, composed of 15 traditional varieties of cowpea and two salinity levels of irrigation water (0.5 and 4.5 dS m−1), with five replicates. Plants were grown in pots containing 10 dm3 of soil for 80 days. The reduction in the photosynthetic rate of cowpea varieties occurs mainly due to the decrease in stomatal conductance caused by salt stress. Salt stress increased the electron transport rate and photochemical quenching of cowpea varieties, but stress-tolerant varieties increased the CO2 assimilation rate and instantaneous carboxylation efficiency. The Ceará, Costela de Vaca, Pingo de Ouro, Ovo de Peru, and Sempre Verde varieties are tolerant to salt stress. Salt stress decreases 26% of the production of tolerant varieties to salt stress and 54% of susceptible varieties. The present findings show the existence of variability for saline stress tolerance in traditional varieties of cowpea and that Ceará, Costela de Vaca, Pingo de Ouro, and Ovo de Peru varieties are more suitable for crops irrigated with saline water.

The Effect of Irrigation Water Quality and Leaching Ratio on Some Yield Parameters in Alfalfa (Medicago Sativa L.)

This study was carried out over the experimental fields of Ankara University, Faculty of Agriculture Gümüşdere Campus. Experiments were conducted with 3 different irrigation water salinity levels (S1=0.25 dS/m – control/tap water, S2=1.5 dS/m, S3=3.0 dS/m) and 4 different leaching ratios (LF1=10%, LF2 =20%, LF3 = 35%, LF4=50%) in randomized plots factorial experimental design with 3 replications. Totally, 36 (3×4×3) lysimeters were used in present experiments. Plant height, fresh and dry herbage yield and total ash content of alfalfa plants were analyzed. With increasing salinity levels, plant height, fresh and dry herbage yields decreased and total ash contents increased. Positive effects of leaching applications were observed, but this effect was not found to be significant. The main reason for this situation may be the necessity of a good drainage system for a good leaching application.

EFFEC OF SALT STRESS ON YIELD AND ITS COMPONENTS OF FOUR CULTIVARS OF BARLER

A field experiment was carried out at the field with clay loam soil in the winter seasons of 2018 - 2019 and 2019 - 2020 in order to study the effect of three levels of salt stress on yield and its components for four cultivars of barley (Hordeum valgare L.(. which be approved in Iraq.Factorial experiment with in Randomized Complete Block design with three replications. The treatments included three levels of irrigation water salinity (5,10,15) ds.m-1 and four cultivars of barley (IPA 99, Buhooth 265, Samir, and Amal). The results showed that the salinity of the irrigation water caused a significant decreases of the number of spikes.m-2, number of grains. spike-1, weight of 1000 grains (gm) and grain yield. plant. -1 at levels S2 and S3 and for both studies seasons in comparison with treatment S1, which gave the highest averages for the mentioned traits, significant differences among barley cultivars in terms of their tolerance to salinity. It was found that Samir cultivar was more tolerant to salinity than the other cultivars.

Effect of irrigation water quantity and salinity level on growth and internal chemical contents of Moringa plants

Effect of irrigation water quantity and salinity level on growth and internal chemical contents of Moringa plants

Estimating crop yield under conditions of soil water deficit and salinity stress with crop water productivity model

The aim of this study was to simulate grain yield, biomass production, canopy cover and water productivity of winter wheat grown under soil water deficit and salinity stress by AquaCrop model. Five different irrigation strategies (S100 - S75 - S50 – S25 and S0) and 5 different irrigation water salinity levels (T1 = 0.3 dS m-1, T2 =5 dS m-1, T3 = 7.5 dS m-1, T4 = 10 dS m-1, T5 = 15 dS m-1) were used with the model to estimate deficit irrigation and salinity stress scenarios. According to estimation of the model the grain and biomass yields were fluctuated in the range of 5.43-8.00 t ha-1 and 12.84-17.67 t ha-1 at irrigation treatments. The application of 25%, 50% and 75% level of deficit irrigation, grain yield reduction was obtained 5%, 13% and 26% respectively. It was compared to the T1 (control) treatment, a low value of 3% was obtained for the T2 treatment. Yield loss of T3 and T4 salinity treatments were found to be 19% and 43% respectively. The crop yield reduction was dramatically (86%) at 15 dS m salinity level of irrigation water. The lowest yield was obtained at all salinity levels in I25 treatment, where 75% water saved. The highest and lowest water productivity was 1.28 kg m-3 and 1.20 kg m-3 respectively. It is possible to irrigate much more areas saving water with deficit irrigation and also the yields obtained from these areas were 2.17, 6.17 and 17.2 tons more than the yields obtained from areas irrigated with full irrigation. For, sustainable water management in agriculture area, using simulation model such as AquaCrop is useful tolls to estimate effect of applied water depth and quality of irrigation water on crop yield.

Mitigation adverse effects of salinity stress on wheat plants by co-inoculation of plant growth promoting rhizobacteria, arbuscular mycorrhizal fungi and compost amendment

Salinity has become one of the most important challenges in agriculture. A pot experiment was conducted during 2017/2018 and 2018/2019 seasons at the greenhouse of Fac. Agric., Cairo Univ., Giza, Egypt, on Triticum aestivum L., var. Gemmiza 10. Plants irrigated with diluted seawater with tap water (control), 4.0 6.0, 8.0 and 10.0 dS m-1 to investigate the utilization of co-inoculation of plant growth promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) and the addition of compost individually or in combination as an environmentally sustainable tools to alleviate the effects of salinity on wheat plants at both 75 days after sowing (DAS) (elongation stage) and 150 DAS (maturity stage). Salinity stress caused significant reduction in shoot height, shoot fresh and dry weights, K+/Na+ ratio and nitrogen, phosphorous and potassium contents of shoot at 75 DAS, however, Na+ concentration increased significantly. At maturity yield and its attributes, nitrogen, phosphorous and potassium contents in grain and straw decreased significantly with increasing irrigation water salinity level. Co-inoculation and/or compost amendments increased significantly the growth parameters and yield components compared to untreated plants under all irrigation water salinity levels.

PRODUÇÃO E CONSUMO HÍDRICO DA BERINJELA SOB ESTRESSE SALINO IRRIGADA POR GOTEJAMENTO CONTÍNUO E PULSOS

ABSTRACT Eggplant is a vegetable considered as moderately sensitive to salinity, and its production is affected by water deficit in the soil, mainly in the reproductive phase of the crop. The objective of this study was to evaluate the use of irrigation with brackish water using continuous drip and pulse in production, water consumption, water use efficiency, and soil salinization. The experimental design was in randomized blocks, in a 4 × 4 factorial scheme, with five replicates, totaling 80 plots. The treatments consisted of four forms of water application, continuous drip, and pulse throughout the cycle; continuous drip in the vegetative phase and pulse in the reproductive phase, and pulse in the vegetative phase and drip in the reproductive phase and four levels of irrigation water salinity - ECw (0.3; 1.5; 3.0; 4.5 dS m−1). The inversion of irrigation treatments occurred 65 days after transplanting. Increase in water salinity from 0.3 to 4.5 dS m−1, the total production (-11.96%), fruit length (-5.05%), and water use efficiency (-7.01%) reduced while there was no significant effect for the forms of water application and interaction between the studied factors. Pulse irrigation provided greater water savings and resulted in higher electrical conductivity in the soil saturation extract. The efficiency of water use did not show statistical difference when continuous drip or pulse irrigation was used throughout the cycle.

PERÓXIDO DE HIDROGÊNIO COMO ATENUANTE DO ESTRESSE SALINO EM MARACUJAZEIRO-AZEDO

ABSTRACT Sour passion fruit is a fruit crop widely cultivated throughout Brazil, due to its adaptation to the tropical climate. However, in semi-arid regions its development is limited by the high concentration of soluble salts in the waters commonly used in irrigation. In this context, exogenous application of low concentrations of hydrogen peroxide can attenuate the damage caused by salt stress. The objective of this study was to evaluate electrolyte leakage, photosynthetic pigments and photochemical efficiency in sour passion fruit cv. BRS Rubi do Cerrado under irrigation with saline waters and foliar application of hydrogen peroxide. A completely randomized design was used, with treatments arranged in split plots, corresponding to five levels of irrigation water salinity - ECw (0.6; 1.2; 1.8; 2.4 and 3.0 dS m−1) and four concentrations of hydrogen peroxide - H2O2 (0; 15; 30 and 45 μM of H2O2) in plots and subplots, respectively. Irrigation with saline water reduced chlorophyll a and total chlorophyll contents of sour passion fruit plants cv. BRS Rubi do Cerrado, at 240 days after transplanting. Hydrogen peroxide at concentration of 15 μM stimulated chlorophyll a and total chlorophyll biosynthesis and, at 45 μM, relieved the effect of 3.0 dS m−1 water salinity on electrolyte leakage in the leaf blade of sour passion fruit. Salt stress did not affect the initial, maximum, variable fluorescence and quantum efficiency of photosystem II of sour passion fruit cv. BRS Rubi do Cerrado.