Salinity Levels Of Irrigation Water Research Articles

Effect of irrigation salinity and ecotype on the growth, physiological indicators and seed yield and quality of Salicornia europaea

The euhalophyte species Salicornia europaea is cultivated for oilseed and as a fodder crop in various parts of the world. In saline coastal environments it possesses great potential for the subsistence of the most disadvantaged farmers. We investigated the effect of salinity levels in irrigation water on the germination capacity, shoot biomass and seed productivity as well as diverse quality traits (nitrogen content in shoots and seeds and fatty acids, in seeds) and physiological traits (stable carbon and nitrogen isotopes and ion content) of two accessions collected in the United Arab Emirates (UAE). The three salinity levels tested were irrigation with fresh water (0.3 dS m−1), brackish water (25 dS m−1) and sea water (40 dS m−1). In addition, a hypersaline condition (80 dS m−1) was also tested for germination. The best germination rates were achieved with seeds exposed to fresh and brackish water, while imbibition with sea water decreased germination by half and hypersaline water inhibited it almost totally. However, the best irrigation regime in terms of biomass and seed yield involved brackish water. Moreover, rising salinity in the irrigation increased the stable isotope composition of carbon (δ13C) and nitrogen (δ15N), together with the Na+ and K+ of shoots and seeds, and the lipid levels of seeds, while the total nitrogen content and the profile of major fatty acids of seeds did not change. Differences between the two ecotypes existed for growth and seed yield with the best ecotype exhibiting lower δ13C and higher K+ in both shoots and seeds, lower Na+ and higher δ15N in shoots, and lower N in seeds, together with differences in major fatty acids. Physiological mechanisms behind the response to irrigation salinity and the ecotypic differences are discussed in terms of photosynthetic carbon and nitrogen metabolism.

Effects of Saline Water and Irrigation Interval on Soybean (Glycine max) Yield

The declining availability of fresh water has become a worldwide problem, which maintains the development of alternative, secondary quality water resources for agricultural use. Several studies recommend that give attention for selected crops that can tolerate a degree of water and salinity stresses when saline water is used for irrigation. In this study, the effects of different irrigation intervals at different salinity levels of irrigation water on Soybean yield and their impacts investigated using three irrigation intervals (I1 =3 days, I2=4 days and I3=5 days) with four salinity levels (S1=4 dSm-1, 5 dSm-1 and 6 dSm-1) in a factorial combination using CRD with three replications. The result showed that salinity, irrigation interval and their interaction were highly significance effects (p<0.001) on number of pod per plant, number of seed per plant and grain yield of Soybean. The highest number of pod number (88.33), grain yield (2.31 ton/ha) and number of seed per plant (172.33) was recorded from Soybean which was irrigated with the first salinity level, i.e., fresh water (S1) with irrigation interval one (3 days), S1I1; while the lowest pod number per plant (6.67), number of seed per plant (12.67) and minimum grin yield (0.034 ton/ha) was obtained from Soybean irrigated by salinity level four (S4) with 5 days irrigation interval (S4I3).

Saline Water Irrigation Through Drip for Groundnut-Wheat Cropping Sequence in Hyper Arid-Region of Rajasthan

A field experiment was conducted to assess the suitability of saline water for irrigation, and to know the irrigation water requirement of groundnut-wheat cropping sequence in hyper-arid region of Rajasthan. In this split-plot experiment, the main plots had four levels of irrigation water salinity (ECiw0.25 (Best available water, BAW), 4, 8 and 12dS.m-1); and the sub-plots had combinations of two treatments on drip lateral spacing of 0.60 m and 0.90 m with 0.30 m emitter spacing, and three levels of irrigation water application (0.6, 0.8 and 1.0 times of pan evaporation (PE)). The highest biological yield (grain + straw) of groundnut and wheat recorded in BAW was statistically at par with irrigation water salinity level of 4 dS.m-1. Higher irrigation water salinity levels (8 and 12 dS.m-1) and placement of laterals at 0.90 m led to significant reduction in biological yield. In monetary terms, use of BAW resulted in highest B:C ratio of 1.73 for groundnut-wheat cropping sequence, while ECiw 4 dS.m-1 showed B:C ratio of 1.70. Highest crop yields, gross return and B:C ratio were observed under 0.60 m lateral spacing and irrigation application at 1.0 PE. Interaction effect of salinity of irrigation water and lateral spacing on yield and yield attributes was significant for both crops. Study demonstrated that the salinity limit of 4 dS.m-1 can be considered as threshold irrigation water salinity for drip irrigated groundnut and wheat crops in hyper-arid region of Rajasthan.

Effect of Different Egyptian Planting Location and Irrigation Water Salinity Level on Gypsophilla Plants Tolerance

Effect of Different Egyptian Planting Location and Irrigation Water Salinity Level on Gypsophilla Plants Tolerance

Naturally colored cotton irrigated with saline water at different growth stages

This study aimed to evaluate the growth, production, and nutrition of naturally colored cotton (cultivar BRS Verde) irrigated with saline water in different growth stages. The trial was conducted with a randomized block design in which the treatments consisted of three irrigation water salinity levels applied throughout the crop cycle or alternately in three growth stages. The lowest-salinity water was drawn from the Arenito Açu aquifer in the state of Rio Grande do Norte, Brazil; the highest-salinity water was prepared to obtain salinity similar to the water drawn from the Calcário Jandaíra aquifer, and an intermediate salinity was obtained from the mixture of equal volumes of the lowest and highest-salinity waters. The application of the lowest-salinity water is recommended in all growth stages due to the increases of about 19% in cotton growth and 40% in yield compared to the application of intermediate or highest-salinity water. The application of the lowest-salinity water in the vegetative stage and the intermediate-salinity water in the following stages is an alternative to using good quality water throughout the cycle, despite the decreases of about 7% in growth and 16% in yield. The nutrition of cotton plants irrigated with saline water throughout the cycle or in some growth stages was marked by an increase of up to 86% in the cotton leaf sodium content, a decrease in the leaf potassium content of up to 21% and increases between 24% and 188% in leaf micronutrient content when the highest-salinity water replaced that with the lowest salinity.

Melon cultivation irrigated with saline waters promote chemical alterations in an acrisol

The objective of the present study was to evaluate the salinization process and the changes in the chemical properties of an Acrisol cultivated with melon irrigated with water of different saline concentrations. The experiment was carried out in the field conditions using the experimental design of randomized blocks, arranged in split-plot. The plots were composed of salinity levels of irrigation water, expressed in terms of water electrical conductivity (ECw): 0.54; 1.48; 2.02 dS m-1; and the sub-plots for melon cultivars: Sancho and Medellín (Toad Skin), Mandacaru (Yellow), Nectar (Galia) and Sedna (Cantaloupe). Soil samples were collected at the beginning and end of the crop cycle to evaluate the changes in the physical-chemical properties of the soil. The electrical conductivity of saturation extract in the soil profile varied for each cultivar, observing high salinity values in soils with cultivars with lower water demand (Sedna and Nectar). The salinity of the soil was lower than the electrical conductivity of the irrigation water in the treatments with high values of ECw. The soil pH values showed little reaction in relation to the initial values. The exchangeable sodium percentage values were approximate twice the sodium adsorption ratio of the saturation stratum.

Influence of water having variable salinity and sodicity on groundnut-II : Effect on nutrient content and uptake

A pot experiment was conducted at Net House, Department of Agricultural Chemistry and Soil Science, College of Agriculture, Junagadh Agricultural University, Junagadh to assess the different levels of saline and sodic irrigation water on content and uptake of nutrient by groundnut during the Summer-2018. The treatment consists of four levels each of salinity (2, 4, 6 and 8 dS m-1) and sodicity (5.0, 10.0, 15.0 and 20.0 SAR) of irrigation water by adopting factorial CRD with three replications. The results indicated that application of different levels of saline and sodic irrigation water produced significant effect on content and uptake of N, P and K by kernel and haulm of groundnut. The highest N, P and K content (3.76 %, 0.34 % and 0.67 %) and uptake (163.6, 13.34 and 25.14 mg pot-1) by kernel and content (1.08 %, 0.15 % and 0.40 %) and uptake (177.8, 25.01 and 66.5 mg pot-1) by haulm, respectively were observed with EC-2 dS m-1 level of salinity of irrigation water, but the lowest content and uptake by kernel were observed with EC-6 dS m-1 and by haulm at EC-8 dS m-1 levels of salinity of irrigation water. There was no any pod formation were observed with EC-8 dS m-1, hence, content and uptake of nutrients by kernel considered zero. While the highest N, P and K content (2.85 %, 0.22 % and 0.42 %) and uptake (109, 5.93 and 11.45 mg pot-1) by kernel and content (1.01 %, 0.13 % and 0.37 %) and uptake (135.5, 17.80 and 48.6 mg pot-1) by haulm, respectively were observed with SAR- 5.0 level of sodicity of irrigation water. The interaction effect between salinity and sodicity levels of irrigation water on concentration and uptake of N by kernel and haulm were found significantly the highest with C1×S1 (EC- 2.0 dS m-1 × SAR- 5.0) level of salinity and sodicity of irrigation water.

Influence of water having variable salinity and sodicity on groundnut- I : Effect on growth, yield attributes, yield and quality

A pot experiment was conducted at Net House, Department of Agricultural Chemistry and Soil Science, Junagadh Agricultural University, Junagadh to assess four levels each of salinity (2, 4, 6 and 8 dS m-1) and sodicity (5.0, 10.0, 15.0 and 20.0 SAR) of irrigation water on groundnut by adopting factorial CRD with three replications. The results indicated that application of different levels of saline and sodic irrigation water produced significant effect on growth, yield attributes, yield and quality of groundnut crop. The maximum plant height, number of mature and immature pods plant-1, weight of mature and immature pods plant-1, days to 50 % flowering, pod and haulm yield and harvest index were observed with EC 2 dS m-1 and SAR 5.0 and the lowest with EC 8 dS m-1 and SAR 20.0 of irrigation water. The quality parameters like seed index and protein content were found maximum with the saline irrigation water level of EC-2 dS m-1 and SAR-5.0, but there was no any pod formation recorded with EC-8 dS m-1. The interaction effect between salinity and sodicity levels of irrigation water on pod (8.10 g pot-1), kernel (5.36 g pot-1) and biological (26.61 g pot-1) yield were found significantly the highest with C1×S1 (EC- 2.0 dS m-1×SAR- 5.0) while no any pod formation were observed with C4×S1, C4×S2, C4×S3 and C4×S4 level of irrigation water.

Potential of Biochar Application to Mitigate Salinity Stress in Eggplant

Salinity stress is among the major abiotic stresses prevailing in arid and semiarid areas such as the southern high plains of the United States. In these areas, both declining quality of groundwater and cultivation practices have resulted in increased accumulation of salts in the root zone. The occurrence of excessive salts in the root zone is detrimental for plant growth and economic yield. Recently, biochar has received a great consideration as a soil amendment to mitigate the detrimental impacts of salinity stress. However, the effectiveness of biochar to mitigate the salinity stress depends on the feedstock type, pyrolysis temperature and time, soil type and properties, and plant species. Therefore, a pot experiment in a greenhouse was conducted to 1) examine the effects of salinity stress on physiology, shoot and root growth, and yield of eggplant (Solanum melongena L.), and 2) evaluate the potential of hardwood biochar and softwood biochar to mitigate the damaging effects of salinity stress on eggplant. The experiment was conducted in a split-plot design with three salinity levels of irrigation water [S0 (control, 0.04 dS·m−1), S1 (2 dS·m−1), and S2 (4 dS·m−1)] as main-plot factor and three biochar treatments [B0 (control, non-biochar), Bh (hardwood biochar), and Bs (softwood biochar)] as subplot factor with four replications. Results showed that stomatal conductance (gS) and photosynthesis rate decreased significantly, while leaf temperature and electrolyte leakage increased significantly with increase in irrigation water salinity levels. Root growth (root length density and root surface area density), shoot growth (plant height, stem diameter, and leaf area), and yield of eggplant declined with increase in levels of salinity stress. Biochar application helped to enhance gS and photosynthesis rate, and to decrease leaf temperature and electrolyte leakage in leaf tissues of plants. This resulted in better root growth, shoot growth, and fruit yield of eggplant in treatments amended with biochar than non-biochar (control) treatment. There was no significant difference in the effect of two types of biochars (hardwood and softwood biochar) on physiology, root growth, shoot growth, and yield of eggplant. Therefore, it can be concluded that softwood and hardwood biochars could be used to minimize the detrimental impacts of salinity stress in eggplant.

Effect of Irrigation Waters in Different Salinity Levels on Crop Yield and Energy Use in Greenhouse Tomato Production in Turkey: A Case Study in Kırklareli Province

This study was carried out in a quonset type plastic covered unheated greenhouse on the lands of Atatürk Soil Water and Agricultural Meteorology Institute in Kırklareli, Turkey. In the study, the effect of different salinity and irrigation water levels which were applied to tomato plant, irrigated by drip irrigation in greenhouse, on yield and energy use efficiency was evaluated and the optimum irrigation application was determined. In the study, ‘Swanson F1’ type tomato was grown as plant material. The trial was carried out on 36 parcels with three repetitions according to split plots trial design and four different irrigation water salinity levels were on main plots and three irrigation levels were on sub plots. The best result was obtained from T1S2 subject in terms of yield and energy use efficiency. The average yield was determined as 109060 kg ha-1 and energy output/input ratio, energy productivity and specific energy were found as 1.51, 1.89 kg MJ-1 and 0.53 MJ kg-1 in T1S2 subject, respectively. It was concluded that the optimum method should be on low salinity level and the irrigation water application should be on the level in order to bring the current moisture level to the field capacity.

Sewage Sludge Impacts on Yields, Nutrients and Heavy Metals Contents in Pearl Millet–Wheat System Grown Under Saline Environment

Salinity prompts heavy metals accumulation and adversely affects nutrient contents in soil and plants, thereby reducing crop yields. The assessment of domestic sewage sludge (SS) under saline conditions to boost crop productivity has become crucial. A field trial was conducted for two consecutive years (2017–2019) with three irrigation levels [canal water (0.35 dS m−1), I1; 8 dS m−1, I2; and 10 dS m−1 saline water, I3]; and five fertilization levels [control, F1; SS (5 t ha−1), F2; SS (5 t ha−1) + 50% RDF, F3; SS (5 t ha−1) + 75% RDF, F4; and RDF, F5]. The results revealed that treatment I3 (10 dS m−1) reduced the grain yield of pearl millet and wheat by an average of 31.2 and 32.6%, respectively, compared to I1 (0.35 dS m−1). However, among fertilizer treatments, F5 obtained significant highest grain and straw yields statistically at par with F4 treatment. Also, in the context of nutrients content in crops, a similar trend has been reported. In the addition, with the usage of saline irrigation (EC 8 and 10 dS m−1) and SS (5 t ha−1), the availability of heavy metals in crops and soil had increased (p = 0.05). The soluble ions in soil increased with increasing salinity levels of irrigation water. The extractability series of heavy metals were: Pb > Co > Ni > Cr > Cd. The addition of SS, however, recorded a higher concentration of DTPA-extractable metals in soil over control. The heavy metals content did not exceed toxicity levels in soil and plants. Hence, the incorporation of SS (5 t ha−1) resulted in saving 25% mineral fertilizers and, also combined use of SS with mineral fertilizers proved to be economically beneficial for crop production.

Micronutrients accumulation under pearl millet-wheat cropping system in response of salinity levels amended with sewage sludge

Aim: The present study was undertaken to evaluate the effect of sewage sludge and saline water irrigation on micronutrients concentration in pearl millet- wheat cropping system. Methodology: The trial was conducted during 2017-2019 at Soil Research Farm, CCS Haryana Agricultural University, Haryana in a factorial random block design with three replications. There were three salinity levels of irrigation water, i.e., canal water (0.35 dS m-1), 8 and 10 dS m-1 EC of saline water; and five fertilization levels, i.e., control (no fertilizer), sewage sludge(5 t ha-1), SS (5 t ha-1) + 50% RDF, SS (5 t ha-1) + 75% RDF and 100 % RDF. However, sewage sludge was applied in Rabi seasons only. Results: Based on pooled analysis of two years, micronutrients (Fe, Mn and Cu) concentration in grain and stover/straw of pearl millet and wheat crops significantly reduced on application of saline water irrigation (ECiw 8 and 10 dS m-1) whereas, Zn concentration was non significantly affected with salinity levels. However, highest concentration of Fe, Mn and Cu was recorded with canal water irrigation. There was a significant increase in micronutrients (Fe, Mn and Cu) concentration in both crops with sewage sludge application in comparison of RDF and control treatments but in case of zinc treatment SS (5 t ha-1) + 75% RDF and 100% RDF were at par with each other. Among treatments, significantly higher concentration of micronutrients was recorded with SS (5 t ha-1) + 75% RDF treatment being at par with SS (5 t ha-1) + 50% RDF. Interpretation: Salinity affects micronutrient availability adversely. However, zinc content was not affected significantly. In such case, sewage sludge application may prove a feasible option that serves as a supplement of nutrients as well as sorting out the problem of dumping waste.

Production and quality of watermelon fruits under salinity management strategies and nitrogen fertilization

The objective of this study was to evaluate the production and quality of ‘Sugar Baby’ watermelon fruits under different strategies of irrigation with saline water and nitrogen (N) fertilization in an experiment conducted in a protected environment in Campina Grande, Paraíba, Brazil. The experimental design adopted was in blocks with a 6 × 2 factorial scheme, corresponding to six strategies of irrigation with saline water applied at different phenological stages of the crop (SE irrigation with low-salinity water throughout the cycle; salt stress at the vegetative stage VE; vegetative and flowering VE/FL; flowering FL; fruiting FR; fruit maturation MAT) and two N doses (50 and 100% of the recommendation, equivalent to 50 and 100 mg of N kg-1 of soil) with five replicates. Two levels of irrigation water salinity were studied, one with low and the other with high electrical conductivity (ECw = 0.8 and 3.2 dS m-1). The salt stress applied at the vegetative and flowering stages reduced the contents of ascorbic acid and total soluble solids in ‘Sugar Baby’ watermelon fruits. The dose equivalent to 50% of the N recommendation promoted a greater fresh weight of watermelon fruits. Fertilization with 100% of N increased the hydrogen potential of watermelon fruits under salt stress at the vegetative and flowering stages. The anthocyanin content of watermelon fruits decreased under salt stress, regardless of the development stage; however, with 50% of recommendation of N, there was an increase in this variable.

Preservation by lactic fermentation and physicochemical characterization of okra produced underwater salinity and potassium fertilization

The use of saline water in agricultural production will be increasingly necessary in the next decades. However, postharvest quality may be compromised, as in okra, due to salt stress and/or factors inherent to storage and transportation. In this context, developing alternative methods of preservation, including lactic fermentation, may be a promising way to maintain and even improve the nutritional quality of okra. Thus, the objective was to evaluate the production components of okra subjected to different levels of water salinity and doses of potassium fertilization, and further to evaluate the preservation by lactic fermentation of okra fruits produced under water salinity. The first experiment was carried out in lysimeters under field conditions in Neossolo Regolítico (Psamment) of sandy loam texture in Pombal-PB, in a randomized block design in a 5 x 5 factorial scheme, testing 5 levels of irrigation water salinity (0.3; 1.3; 2.3; 3.3, and 4.3 dS m-1) and 5 doses of potassium fertilization (75; 112.5; 150; 187.5, and 225 mg of K2O kg-1 of soil), with three replicates. After that, the okra fruits produced under the different salinity levels were stored in six mixtures of salts present in lactic fermentation brine (100-0-0, 0-100-0, 0-0-100, 50-50-0, 0-50-50, and 50-0-50 of NaCl, CaCl2, and KCl, respectively), under a 5 x 6 factorial, with three replicates, in a completely randomized design. The post-harvest quality, after fermentation, was evaluated based on their physicochemical characteristics. Irrigation water salinity negatively affected the average length, average weight, titratable acidity, soluble solids/titratable acidity ratio, and pH of the okra fruits. Potassium doses increased the average diameter of okra fruits, minimizing the deleterious effects of irrigation water salinity. The vitamin C contents of pickled okra fruits were not compromised by salt stress. Among the lactic fermentation brines, the formulation containing the proportion NaCl:CaCl2 stands out as promoting the highest titratable acidity and soluble solids content in pickled okra fruits.

Effect of irrigation water salinity on a wheat culture (Triticum durum) in the presence of organic matter

Salinity is one of the most important problems that agriculture faces in the arid and semi-arid areas. That was motivated us to look at one of its aspects, which is irrigation water salinity, but with organic matter amounts to reduce the deterioration caused by this kind of water, and to come out with the right doses of organic matter at different levels of irrigation water salinity. We have applied three levels of irrigation water salinity: S1= 5 dS m-1, S2= 9 dS m-1 and S3=13 dS m-1, with three organic matter doses: F0= 0 t/ha, F1= 30 t/ha and F2= 60 t/ha. The results obtained were very encouraging and important through the noticeable impact of the measures studied. The positive impact of organic matter amounts on the saltiest treatments has been manifested, unlike the less salty treatments that they lack and we can say that the dose of 60 t/ ha of poultry manure is the best to increase the production of grains yield and straw yield, but the dose of 30 t/ha is the optimal dose to increase the weight of 1000 grains. This confirms the effectiveness of it responding to the irrigation water salinity effects, which is manifested in better plant yield.

CELL DAMAGE AND BIOMASS OF YELLOW PASSION FRUIT UNDER WATER SALINITY AND NITROGEN FERTILIZATION

ABSTRACT The aimed of this study was to evaluate the attenuating action of nitrogen doses on leaf cell membrane damage, dry biomass production and leaf area in the formation of yellow passion fruit seedlings irrigated with saline water. Treatments were arranged in a randomized block design, in split plots, corresponding to five levels of irrigation water salinity (plot) (ECw) (0.3; 1.0; 1.7; 2.4 and 3.1 dS m-1) and five doses of nitrogen fertilization (subplot) (60; 80; 100; 120 and 140% of 300 mg of N dm-3), which were repeated in five blocks. Plants were grown in pots (Citropote®) with a volume of 3,780 mL, which were filled with a mixture of soil, aged bovine manure and sawmill residue (shaving) in a ratio of 2:1:0.5, respectively. Waters with different levels of salinity were applied from 40 to 85 days after sowing, when the plants were in transplanting conditions. At 85 days after sowing, the percentage of cell damage based on electrolyte leakage, variables of dry biomass, leaf area and specific leaf area were evaluated. Increment in irrigation water salinity reduces the biomass accumulation of yellow passion fruit seedlings; The increase in nitrogen dose did not mitigate the effect of salinity, which reduced cell membrane integrity, making the plant more sensitive.

RESPONSE OF PEAR SEEDLINGS TO SOME NON-AND MAGNETIZED SALINE IRRIGATION WATER AND HUMIC ACID AND THEIR EFFECT ON GROWTH, LEAF PHYSIOLOGICAL PROPERTIES, LEAF PIGMENTS AND ELEMENTS CONTENTS

This study was conducted during two successive seasons of 2018 and 2019 at El Kanater Horticultural Research Station, Qalyoubeia Government Egypt. The aim of this investigation was to study the effect of salinity levels of non-and magnetized irrigation water alone and in combination with humic acid on one-year-old pear seedlings (Pyrus communis) rootstock. Obtained results revealed that, the two higher concentrations of saline water (1500 and 3000 mg/l) resulted in a gradual significant decreased in all vegetative measurements, dry weights of pear seedling organs, both leaf succulence grade, water potential and leaf content of pigments as well as some leaf elements contents of N, P, K, Mg, Fe, Zn and Mn, Whereas an opposite trends were observed with leaf osmotic pressure, proline content and leaf content of Ca, Na and Cl as compared to the control (270 mg/l –fresh water). On the other hand, seedlings treated with either humic acid or magnetized water were exited significantly an increasing values of vegetative parameters, dry weights of different plant organs, leaf pigments and some macro and micro-nutrients beside Na and Cl as well as both leaf succulence grade and water potential as compared to control (non-magnetized water or non-humic acid) in both seasons of study. The obtained data concluded that the use of magnetized water technique with humic acid applications would be efficiently and safe alternative tool to resolve the problem of irrigating with saline water and to enhance pear rootstock seedlings growth grown under similar conditions of this study.

RESPONSE OF PEAR SEEDLINGS TO SOME NON-AND MAGNETIZED SALINE IRRIGATION WATER AND HUMIC ACID AND THEIR EFFECT ON GROWTH, LEAF PHYSIOLOGICAL PROPERTIES, LEAF PIGMENTS AND ELEMENTS CONTENTS

This study was conducted during two successive seasons of 2018 and 2019 at El Kanater Horticultural Research Station, Qalyoubeia Government Egypt. The aim of this investigation was to study the effect of salinity levels of non-and magnetized irrigation water alone and in combination with humic acid on one-year-old pear seedlings (Pyrus communis) rootstock. Obtained results revealed that, the two higher concentrations of saline water (1500 and 3000 mg/l) resulted in a gradual significant decreased in all vegetative measurements, dry weights of pear seedling organs, both leaf succulence grade, water potential and leaf content of pigments as well as some leaf elements contents of N, P, K, Mg, Fe, Zn and Mn, Whereas an opposite trends were observed with leaf osmotic pressure, proline content and leaf content of Ca, Na and Cl as compared to the control (270 mg/l –fresh water). On the other hand, seedlings treated with either humic acid or magnetized water were exited significantly an increasing values of vegetative parameters, dry weights of different plant organs, leaf pigments and some macro and micro-nutrients beside Na and Cl as well as both leaf succulence grade and water potential as compared to control (non-magnetized water or non-humic acid) in both seasons of study. The obtained data concluded that the use of magnetized water technique with humic acid applications would be efficiently and safe alternative tool to resolve the problem of irrigating with saline water and to enhance pear rootstock seedlings growth grown under similar conditions of this study.

PRODUCTION AND QUALITY OF MINI WATERMELON UNDER DRIP IRRIGATION WITH BRACKISH WATER

ABSTRACT Watermelon plays an important role in Brazilian agribusiness. The objective of present study was to evaluate the effect of different irrigation managements and water salinity levels, on the main productive and postharvest characteristics of mini-watermelon (Citrullus lanatus) cv. ‘Sugar Baby’. The experiment was conducted in a greenhouse in a completely randomized design, arranged in a 2 x 4 factorial scheme, with four replicates. The treatments consisted of two types of irrigation management (conventional and pulse) and four saline levels of nutrient solution of fertigation (2.5; 4.5; 5.5; 6.5 dS m-1). The control treatment corresponded to the electrical conductivity of the nutrient solution prepared with local supply water. The irrigation depth was calculated by the product of reference evapotranspiration and crop coefficient. The number of pulses were defined and fractionated according to the atmospheric demand. The salinity of the fertigation solution affects some variables of the production, but does not reduce the quality of the mini-fruit cv. ‘Sugar Baby’. The management of pulse irrigation shows better results in low salinity, while conventional drip management is more suitable for high salinity (6.5 dS m-1).

Optimization-Based Water-Salt Dynamic Threshold Analysis of Cotton Root Zone in Arid Areas

Threshold levels of soil moisture and salinity in the plant root zone can guide crop planting and farming practices by providing a baseline for adjusting irrigation and modifying soil salinity. This study describes a method of soil water and salinity control based on an optimized model for growing cotton in an arid area. Experiments were conducted in Akesu Irrigation District, southern Xinjiang, northwest China, to provide data for cotton yield and soil water content and salinity in the root zone at different growth stages. The sensitivity of cotton to soil water content and salinity was predicted for different growth periods using a modified Jensen model. An optimization model with 480 boundary conditions was created, with the objective of maximizing yield, to obtain the dynamically varying water and salt threshold levels in the root zone for scenarios that included three initial soil moisture content values (W0), eight irrigation quantities (M), five initial soil salt content values (S0), and four irrigation water salinity levels (K). Results showed that the flowering–boll stage is the crucial period for cotton yield, and the threshold levels of soil water content and salinity in the cotton root zone varied with the boundary conditions. The scenario chosen for the research area in this study was W0 = 0.85θfc (θfc is field capacity), S0 = 4 g kg−1, M = 400 mm, K = 0 g L−1. The predicted threshold levels of soil water for different growth stages (seedling, bud, flowering–boll, and boll-opening) were respectively 0.75–0.85θfc, 0.65–0.75θfc, 0.56–0.65θfc, and 0.45–0.56θfc. Corresponding threshold levels of salt were 4–4.16, 4.16–4.39, 4.39–4.64, and 4.64–4.97 g kg−1 when no action was taken to remove salt from the root zone. This study provides an innovation method for the determination of dynamically varying soil water content and salt thresholds.