Impact of Saline Water Irrigation on Soil Salinity, Growth, and Productivity of Triticale in Sandy Soil

Abstract

Salinity and water scarcity are among the major environmental challenges requiring the use of non-conventional water sources and the adoption of salt-tolerant crops. We assessed the impact of irrigation with different concentrations of NaCl: 50 mM and 150 mM on the growth parameters and yield of triticale, soil salinity, distribution of active root density, and concentrations of Na⁺ and NO₃⁻ ions at harvest compared to freshwater under zero leaching conditions. Irrigation was applied on a daily basis based on weight measurements of micro-lysimeter pots. Growth parameters, including plant height, LAI, number of leaves, number of tillers, and soil salinity, were observed across the growing season. Spatial distributions of soil salinity, normalized root length density (NRLD), concentrations of Na⁺ and NO₃⁻ in soil profile were measured in two dimensions. The results indicate that irrigating with 150 mM of NaCl H₂O significantly affected the crop growth, causing salts, particularly Na⁺, to reside in the topsoil, reducing NRLD with soil depth, crop water demand, and NO₃⁻ uptake. The application of 150 mM and 50 mM of NaCl H₂O reduced crop water use by 4 and 2.6 times as well as grain yield by 97% and 42%, respectively, compared to freshwater. This shows that irrigation with concentration equal to or higher than 150 mM NaCl will result in very low production. To achieve higher yield and crop water productivity, irrigation with NaCl concentration of 50 mM or less is recommended to grow triticale in marginal regions with limited freshwater resources.

1. Introduction

Soil salinization and water scarcity are two major challenges for global agricultural production. The adverse impacts of these two constraints on crop productivity, in addition to land degradation, are expected to exacerbate further with climate change, particularly in marginal regions [1]. Irrigated arable land accounts for more than 20% of overall salt-affected lands [2] and due to scarce water resources, it has significantly increased. To achieve sustainability goals in terms of food security, all agricultural production components should be integrated, and all available conventional and non-conventional water resources should be wisely utilized [3].

In irrigated soils with poor-quality water, the adoption of salt-tolerant crops is highly recommended for sustainable crop production [4]. Triticale is a cross between wheat and rye [5,6] and can successfully grow in marginal lands due to its tolerance to drought and salinity stresses [7,8]. The average content of proteins, carbohydrates, fibers, free sugars, and ash in triticale is reported as 10%, 56%, 2.8%, 4%, and 1.6%, respectively [3]. This highlights the economic importance of triticale as a substitute crop for rye and wheat. Despite its high economic value, only a few studies have evaluated the impact of saline water irrigation on seasonal crop water use, soil salinity, and yield. Most studies have focused on evaluating the impact of saline water irrigation on seed germination or early growth stage of triticale [9] and combined water and salt stresses on qualitative, biochemical, and morpho-physiological traits of triticale [10,11,12,13,14]. Studies have also been performed on quantifying the impact of salinity on crop evapotranspiration (${ET}_c)$, while leaching is applied [15]. These studies have concluded that triticale growth during the flowering stage is more sensitive to salinity than other stages, and despite the reduced biological yield, it is tolerant to different salinity levels depending on the genotype [16]. Grieve et al. [17] reported that triticale is moderately salt tolerant with a threshold value of 6.1 dS m⁻¹. Therefore, salinity tolerance needs to be quantified to select suitable varieties for specific soil and climatic conditions [18]. Crop response to salinity stress is influenced by various factors, including genotype, growth rate, irrigation water quality, and stress duration [19,20]. Application of saline water causes salt to reside and accumulate in the root zone, which may surpass plant salt tolerance, resulting in detrimental effects on plant growth [21]. Excessive sodium chloride (NaCl) in soil water restricts root growth, reduces transpiration rates, and reduces nutrient uptake, leading to nutritional imbalance in plants [4,22,23]. Under dry conditions, it also creates a salt crust layer on the soil surface, which causes resistance to water vapor flux to the atmosphere [24,25]. On the other hand, fertigation with subsequent application of saline water results in a high soluble sodium content in the crop root zone, reducing soil permeability [26]. Guo et al. [27] investigated the long-term effects of saline water application on soil physicochemical properties and nitrogen transformations. Che et al. [28] modeled different scenarios for balancing salt leaching and nitrogen loss for drip irrigation when saline water irrigation is applied. They concluded that when using saline water, irrigation with 100% ET_c is suggested. Several studies have evaluated the impact of brackish groundwater on chemical, thermal, and mineralogical properties of soil [29,30], but only a few have evaluated such impact on the soil–plant system of triticale. To reduce irrigation water losses from evaporation and deep percolation, crop water requirements need to be determined.

In salt-affected soils, irrigation water requirements (IWR) are determined by estimating ${ET}_c$ and leaching requirements (LR) to maintain favorable salt balance in the root zone. The ${ET}_c$ can be measured using different approaches, including empirical methods such as Blaney and Criddle [31]), physical-based methods such as FAO-56 Penman-Monteith [32]), or direct methods using lysimeters [33]. Lysimeter techniques provide reliable measurements, but owing to the high costs associated with their acquisition, installation, and maintenance, their use is very limited. Alternatively, cost-effective pot micro-lysimeters (PMLs) can be used [34,35]. Kankarla et al. [15] used the water balance equation to estimate ${ET}_c$ for triticale grown in 4 L pots, which was not enough to accommodate root growth, especially when the duration of experiments is long.

This study aimed at evaluating the impact of different salinity irrigation water on crop growth, yield components, both Na⁺ and NO₃⁻ concentrations in soil, and root zone salinity development when no additional water is applied for salt leaching.

2. Materials and Methods

2.1. Experiment Design

An experiment for triticale (a winter Wheat × Secale L., cv. Kender crop) was carried out in a glasshouse in the Arid Land Research Center (35°32′05.7″ N, 134°12′41.3″ E) during 2022/23. The newly released triticale variety “Kender” was used for this experiment. This variety is considered suitable for the hyper-dry climate of the Aral Sea Basin. Initially, two triticale seeds were sown in each vinyl poly pot with 350 g of soil on 15 November 2022 and irrigated with freshwater until they were transplanted into the experiment on 28 November 2022. The experiment comprised two distinct sections: triticale seedlings were transplanted in glasshouse soil (main section), while in the other section, the plants were grown in Wagner pots as shown in Figure 1.

The main section of the experiment was designed in a randomized complete block design with three treatments and five replicates. The treatments were: (a) irrigation with freshwater (control), (b) irrigation with 50 mM of NaCl H₂O, and (c) irrigation with 150 mM of NaCl H₂O. The NaCl concentrations in irrigation water were set in terms of the classification of water quality, where 50 mM and 150 mM were classified as moderately saline and saline, respectively [36]. Irrigation was applied through a drip irrigation system with an emitter discharge set at 1 L h⁻¹. The spacings between laterals and emitters were 50 cm and 25 cm, with one emitter for each plant. In the second section, two Wagner pots served as micro-lysimeters to measure daily ${ET}_c$ for each treatment, and they were irrigated with the corresponding water quality. Two more pots were used to provide potential transpiration ($T_p$), which was achieved by covering the soil surface of the pots. The potential transpiration pots were irrigated with freshwater as with the control pots. Each pot had a height of 29.5 cm, an upper diameter of 25.2 cm, and a lower diameter of 23.8 cm. The surface of the pots were set up to be at the same level as the soil surface. The soil was sand with hydraulic properties as shown in Figure 2.

Soil was packed into each pot at a bulk density of 1.5 g cm⁻³ to imitate the soil structure in the main phase. Each pot was well-irrigated according to the designed treatment to retain soil water content around the field capacity (FC: upper boundary of total available soil water). This was adjusted to prevent the plant from experiencing drought stress, and the effect will be solely limited to salinity stress. The drainage orifice at the bottom of each pot was entirely sealed to prevent any solutes from seeping through drainage. The reasoning for this was to assess the accumulation of salt in the soil profile and its influence on plant growth. Liquid NPK fertilizer (6-10-5) was applied to each treatment at a rate of 1 g L⁻¹ day⁻¹. Irrigation was applied on a daily basis according to the ${ET}_c$ measured by pots allocated to each treatment from 6 December to 25 May 2023. The daily soil water depletion in each pot was replenished to return the soil water content to FC. The crop was harvested on 1 June 2023.

2.2. Measurements

Daily ${ET}_c$ and $T_p$ (mm) were measured by weighing the PMLs every morning using a 30 kg weighing balance (EK-30KL, AND, San Jose, CA, USA) as:

$${ET}_c \mathrm{o}\mathrm{r} T_p={\displaystyle \frac{W_j-W_{j-1}}{0.1 A_s}}$$

(1)

where $W_j$ is the pot weight at day $j$ (g); $W_{i-1}$ is the pot weight at the previous day (g); $A_s$ is the surface area of the pot (cm²). The daily irrigation was applied to the main section based on daily ${ET}_c$ observed by the PMLs. The meteorological data (Figure 3) was measured using a weather station (ATOMS 41, Meter, Pullman, DC, USA) to estimate the daily ${ET}_0$ using the FAO Penman Monteith method [13].

Soil samples were collected at 10, 37, 58, 93, and 134 days after planting (DAP) to estimate moisture content and electrical conductivity (EC). EC was measured in soil:water extract of 1:2. The observation of EC was carried out in two dimensions: lateral distance apart of drip tube (0 cm, 10 cm, and 20 cm) and soil depth (0 cm, 5 cm, 10 cm, 20 cm, and 30 cm). A soil moisture, bulk EC, and temperature sensor (TEROS12, Meter, Pullman, USA) was located at a depth of 10 cm for 50 and 150 mM NaCl treatments.

The sensors were calibrated in terms of volumetric water content, $\theta$ (cm³ cm⁻³) and electrical conductivity of soil water, ${EC}_{sw}$ (dS m⁻¹) in order to estimate the solute concentration in soil, $C_{s_j}$ as:

$$\theta =0.99 x-0.0026$$

(2)

$${EC}_{sw}={\displaystyle \frac{{EC}_b}{1.21 {\theta }^{1.78}}}$$

(3)

$$C_{s_j}=0.5{{EC}_{sw}}^{1.038}$$

(4)

where $x$ is the sensor output for $\theta$ (cm³ cm⁻³), ${EC}_b$ is the bulk EC measured by sensor (dS m⁻¹), and $j$ is the time in hours. Average daily volumetric water content, ${\overline{\theta }}_i$, and solute concentration in soil, ${\overline{C}}_i$ (g L⁻¹), were calculated using the forward difference method as [37]:

$${\overline{\theta }}_i={\displaystyle \frac{{\theta }_{i_b}+{\theta }_{i_a}}{2}}$$

(5)

$${\theta }_{i_{(b,a)}}={\displaystyle \frac{ W_{i_{(b,a)}}-W_0}{V_{\mathrm{p}}{\rho }_w}}+{\theta }_r$$

(6)

$${\overline{C}}_i={\displaystyle \frac{C_{i_b}+C_{{(i+1)}_a}}{2}}$$

(7)

$$M_i={\displaystyle \frac{ W_{i_a}-W_{i_b}}{{\rho }_w}}{C}_{iw}+M_{i-1}$$

(8)

$$C_{i_{(b,a)}}={\displaystyle \frac{M_{i_{(b,a)}}}{{\theta }_{i_{(b,a)}}{V}_{\mathrm{p}}}}$$

(9)

where $W_0$ is the initial weight of the pot at the beginning of the experiment (g); W is a daily weight of the pot (g), $V_{\mathrm{p}}$ is the total volume of the pot (cm³); ${\theta }_r$ is the volumetric water content at airdry condition; ${\rho }_w$ is the density of water (g cm⁻³); $C_{iw}$ is the concentration of irrigation water (g m⁻³); M is the mass of added salt (g); the subscripts: $i$, $a,$ and $b$ refer to irrigation day, after irrigation, and before irrigation, respectively. The concentration of nitrate (NO₃⁻) and sodium (Na⁺) in the soil samples (mg L⁻¹) were measured using LAQUAtwin NO3-11C and Na-11 probes (Horiba, Miyanonishi-cho, Kisshoin Minami-ku, Kyoto, Japan) after performing multi-point calibration with the relevant standard buffer.

Growth parameters of triticale were recorded on the same date of soil sample collection, including plant height (cm), leaf area index (LAI), number of leaves, and number of tillers. LAI was calculated as:

$$LAI={\displaystyle \frac{\forall \sum _{k=1}^n{L}_{w_k}\times L_{l_k}}{A_p}}$$

(10)

where $L_{w_k}$ and $L_{w_k}\mathrm{r}\mathrm{e}\mathrm{p}\mathrm{r}\mathrm{e}\mathrm{s}\mathrm{e}\mathrm{n}\mathrm{t}$ the width and length of each leaf, $k$ (cm); $A_p$ is the projected area of plant (cm²); $n$ is total number of leaves; $\forall$ is the leaf shape factor, which was calculated by establishing the relationship between the digitized images of collected sample of leaves (using Simple Digitizer software 3.2 [38]) and the calculated rectangle area of the samples. It was about 0.78.

At harvest time, the two-dimensional spatial distribution of normalized root density (NRLD), θ, solute concentration, NO₃⁻, and Na⁺ along the soil profile were carried out on the quarter of $A_p$. The soil profile was divided into 50 grids. A soil sample from each grid (5 cm × 5 cm) was collected to measure such data, while bulk soil of each grid was collected and wet-sieved to extract all existing roots. The extracted roots of each grid were scanned on an A4 flatbed scanner at 600 dpi, where the total length was quantified using the Newman method [39].

The crop water productivity (CWP) was calculated as:

$$CWP={\displaystyle \frac{Y}{I}}$$

(11)

where $Y$ is the crop yield (kg ha⁻¹) and $I$ is total applied irrigation (mm). Grain yield and yield components including plant height (cm), number of tillers per plant, number of spikes per plant, spike length (cm), spike width (cm), weight of 100-grain weight (g), total fresh biomass (g), and total dry biomass (g) were estimated and statistically analyzed with a randomized complete block design using R (version 4.0.2, R Foundation for Statistical Computing, Vienna, Austria).

3. Results and Discussions

3.1. Impact of Saline Water Irrigation on Crop Water Demand

Irrigation was applied for each treatment based on actual daily ${ET}_c$ as shown in Figure 4 (a: freshwater, b: 50 NaCl H₂O and c: 150 NaCl H₂O). The PMLs were initially saturated with freshwater until 21 DAP. At 21 DAP, irrigation with freshwater, 50 mM and 150 mM of NaCl H₂O were applied to each corresponding pot. The daily application of NaCl H₂O began after 75 DAP when the soil moisture content dropped below FC.

The delay in daily irrigation application between 21 and 75 DAP owed to lower soil water losses driven by lower ${ET}_0$. Since the drainage ceased from the bottom of each PML, which was required to prevent salt and nutrient leaching, water loss was directly related to crop evapotranspiration. The irrigation was managed in PMLs to retain soil moisture around FC, hence preventing drought stress from occurring. The cumulative applied irrigation with different NaCl concentrations as well as fluctuation of ${ET}_0$, as illustrated in Figure 5a. The cumulative irrigation of each treatment was almost the same until the changing point (76 DAP). After this point, the crop instantly developed as the ${ET}_0$ began to rapidly increase due to decreasing relative humidity and increasing air temperature and solar radiation (Figure 3). Higher NaCl concentrations have significantly affected the ${ET}_c$ due to the occurrence of salinity stress. For example, the total applied irrigation for 150 mM NaCl treatment was four times less than the control treatment. Kankarla et al. [15] reported that ETc was significantly higher when triticale was irrigated with freshwater compared to saline irrigation at 8 dS m⁻¹. Ben Ali et al. [30,40] observed that frequent irrigation with saline water caused significant reduction in cumulative ETc rate. In 50 mM NaCl treatment, irrigation was applied equivalent to the calculated ${ET}_c$-based FAO, but 2.6 times less than the control. These results were consistent with Goet et al. [41], who reported that increased salt concentrations in irrigation water reduced plant root water uptake, inhibited plant growth, and decreased soil moisture content. Ben Ali et al. [38] reported that fluctuation of soil water content under the application of saline water with 8.6 g L⁻¹, which is almost the equivalent of 150 mM NaCl, was low. This was due to increased osmotic potential, which reduced root water uptake and thus ET rate. The reasoning for the significant irrigation application to the control was the significant increase of crop canopy and root density, which resulted in potential water and nutrient uptake. By recording total irrigation applied to transpiration PMLs, we observed that the crop in control PMLs utilized 85% of applied irrigation during transpiration as shown in Figure 5b. The maximum water consumption occurred in the mid-growth stage which ranged between 105 and 135 DAP for both 50 mM NaCl and 150 mM NaCl treatments, and between 110 DAP and 145 DAP for freshwater treatment. The crop thereafter began to gradually mature (Figure 5b).

3.2. Impact of Saline Water Irrigation on Soil Salinity and Nutrients Fate

The effect of frequent application of NaCl H₂O on the evolution of soil salinity below the dripper at three soil profile depths: 0 cm (surface), 5 cm, and 10 cm are illustrated in Figure 6. The application of NaCl H₂O has significantly resulted in the build-up of salts in the soil profile, particularly on the topsoil layer (0–5 cm). This was due to a significant decrease in the evaporation rate as observed in Figure 5. Salt accumulation on the soil surface causes reduction in evaporation rate owing to three mechanisms: (i) reduced osmotic potential [42], (ii) resistance to water vapor movement to atmosphere owing to salt crust [24], and (iii) reduced temperature caused by enhanced albedo of salt crust [25]. Li and Shi [43] also reported that elevated salt crust caused by salt precipitation could reduce the evaporation rate by more than 60%. The dynamic effects of NaCl concentrations on soil and plant system were investigated using hourly data of calibrated θ and salt concentration values observed by the sensors after December 25, as shown in Figure 7. The fluctuation of θ in 50 mM NaCl treatment was higher than 150 mM NaCl. In contrast, the solutes concentration under 150 mM NaCl was relatively higher compared to 50 mM NaCl. This can be attributed to the large irrigation amounts applied to 50 mM NaCl, which resulted in less solutes application compared to 150 mM NaCl. The two-dimensional spatial distribution of soil salinity at the harvest is demonstrated in Figure 8. Irrigation with 50 mM and 150 mM of NaCl H₂O over the growing season resulted in building up of salt, particularly in the top 5 cm of the soil profile. The contour maps presented in Figure 8c and Figure 8b show the significant effect of saline water irrigation with 150 mM NaCl and 50 mM NaCl, respectively, on the accumulation of salts in soil profile compared to irrigation with freshwater (Figure 8a). Burkhardt et al. [44] reported that irrigating with poor-quality water increased soil salinity and negatively affected the structure and hydraulic properties of soils. Soil salinity causes three different types of stress, including osmotic, ionic, and secondary stress [45]. Osmotic stress decreased the capability of the plant to absorb water from soil solution, resulting in water deficit in the plant itself. Ionic stress is induced by high concentrations of Na⁺ and Cl⁻ ions that eventually affect the enzymatic activities [46]. The Na⁺ ion has a detrimental impact on plant growth, water uptake, nutrient imbalance, permeability, and microbial activity [4]. Therefore, we presented the two-dimensional spatial distribution of Na⁺ ions in the soil profile in Figure 9. Application of 150 mM NaCl has severely caused accumulation of Na⁺ in the plant active rootzone compared to 50 mM NaCl and freshwater, respectively. Similarly, Atak et al. [47] observed that increasing NaCl application levels could increase the accumulation of Na⁺ ions. The accumulation of Na⁺ ions in soil or plant organs negatively reduces the net photosynthetic assimilation rate of CO₂, reducing crop productivity [23]. Excessive build-up of Na⁺ ions resulted in nutrient imbalance due to the secondary stress caused by osmotic and ionic stresses [48], particularly in NO₃⁻ concentrations as shown in Figure 10. The NO₃⁻ concentrations in 150 mM NaCl treatment were higher in the topsoil layer, particularly at 5 cm apart from the plant. This was because, in localized irrigation, solutes including nutrients are radially leached from the emission point (drippers) where the moisture level is high; therefore, the concentrations steadily increased until they reached their peak at the edge of the wetting perimeter. In contrast, the application of 50 mM NaCl H₂O has no significant effect on NO₃⁻ uptake (Figure 10b), where the uniform distribution was achieved along the soil profile as crop water use was equivalent to crop ET estimated by the FAO method. The plants irrigated by freshwater consumed a significant amount of water that caused the application of more NO₃⁻ compared to the other treatments. Thus, most of the applied NO₃⁻ was absorbed by the dense plant roots, leading to increased biomass accumulation, whereas the rest was leached deeper beyond the root zone (Figure 10a). The results are comparable with those reported by Rasouli et al. [49], whereby excessive salt levels can impair hormonal balance, hinder photosynthesis, and reduce protein synthesis due to decreased both root water and nitrate uptake. Akgün et al. [50] found that nitrogen uptake was highest in the control and lowest when the salt content was high.

3.3. Impact of Saline Water Irrigation on Plant Growth

The application of saline irrigation in the form of NaCl solution may have detrimental impacts on crop growth depending on the concentration level used and crop tolerance to salinity. We have investigated the effect of NaCl solution on four growth parameters of triticale as illustrated in Figure 11. These parameters include plant height, which is an indicator for overall plant health (Figure 11a), LAI, number of produced leaves, which are the most crucial parameters influencing photosynthesis, water and nutrient uptake, as well as crop productivity (Figure 11b,c), and number of tillers, which are directly related to vegetative biomass accumulation and has a significant effect on final crop productivity (Figure 11d). The growth parameters of triticale during tillering and vegetative growth stages were influenced by lower values of ${ET}_c$ as shown in Figure 5b. The frequent application of NaCl H₂O has significantly reduced the crop height, particularly after 58 DAP. In general, the application of 150 mM NaCl H₂O significantly reduced the plant height, LAI, number of leaves and number of tillers compared to 50 mM NaCl H₂O and freshwater, respectively. This was due to decreasing the osmotic potential caused by build-up of salts in the soil profile, which significantly reduced root water and nutrient uptake. These results matched with those published by Miao et al. [51], Kumar et al. [52], and Ullah et al. [53] on the effects of salinity on the plant growth, particularly the toxic effect of Na⁺ and Cl⁻ on the presented parameters. Another reason is the effect of NaCl concentration on root development as shown in Figure 12. The observed NRLD and plant rooting depth was highly affected by irrigation with 150 mM NaCl, where the maximum horizontal root growth was almost 15 cm with a maximal vertical growth of 10 cm. The active root density increased as the concentration of NaCl decreased. Similarly, Kankarla et al. [22] observed that high concentrations of NaCl in irrigation water significantly decreased fresh and dry root biomass. Atak et al. [47] found that root length decreased with increased NaCl concentration. Ion imbalance induced by excessive concentration of NaCl retards root growth, resulting in a smaller root system, lower soil water content and nutrient uptake, and subsequently decreased plant growth [54].

3.4. Impact of Saline Water Irrigation on Yield, Yield Components, and Crop Productivity

The impact of NaCl H₂O application on yield attributes is illustrated in

Table 1. The effect of different irrigation water quality on yield components of triticale.

Yield Attribute	Unit	Treatments
		Freshwater	50 mM NaCl	150 mM NaCl
Plant height	cm	109 ± 1.9 a	83 ± 2.3 b	59 ± 9.3 c
Num. tillers	-	47 ± 5 a	14 ± 1 b	2 ± 0 c
Number of spikes	-	14 ± 2 a	6 ± 0 b	1 ± 0 c
Spike length	cm	15.9 ± 0.5 a	14.8 ± 0.4 a	9.5 ± 0.4 b
Spike width	cm	1.1 ± 0.1 a	0.9 ± 0 a	0.8 ± 0.3 a
100 grain weight	g	3 ± 0.3 a	2.7 ± 0.1 a	1.8 ± 0.1 b
Total fresh biomass	g	189.8 ± 18.1 a	64.6 ± 6.9 b	7.3 ± 1.8 c
Total dry biomass	g	133.3 ± 14.2 a	59.1 ± 6.1 b	4 ± 0.9 c

The values presented by mean ± standard error followed by the same lowercase letter(s) are not significantly different at a 5% level of probability, according to the LSD test.

. Irrigation with 150 mM NaCl has most significantly affected plant height, number of tillers, number of spikes, total fresh biomass, and total dry biomass, followed by 50 mM NaCl and freshwater, respectively. There were no significant differences among all treatments in spike width. The application of 150 mM NaCl H₂O had a significant effect on both spike length and weight of 100 grains, while no difference was found between 50 NaCl H₂O and freshwater. These results were expected as the distribution of roots within the soil profile directly affects the crop water use and hence crop yield and yield components [55]. Goet et al. [41] also reported that increased salinity levels in irrigation water reduce LAI, root depth, and consequently crop yield [56]. Despite equal application of NPK fertilizer to all treatments, the control resulted in higher NPK inputs due to higher water use. This might have increased the number of spikes and the weight of 1000 grains as reported by Rzążewskaand Gąsiorowska [57]. The maximum reported weight of 1000 grains ranged between 35 and 40 g [58], which is consistent with our observations. Figure 13 shows the comparison of grain yield, total applied irrigation, and crop productivity among the treatments. Saline irrigation with concentrations of 150 mM and 50 mM NaCl significantly decreased grain yield by 97% and 42%, respectively, compared to freshwater. The treatments of 150 mM NaCl and 50 mM NaCl consumed 75% and 62% less water than the freshwater treatment, respectively. As a result, the crop water productivity was significantly affected by higher NaCl concentration (150 mM). The highest CWP was obtained under 50 mM NaCl treatment followed by freshwater treatment (Figure 13). This was owed to excess water demand by the plants grown under freshwater treatment.

For sustainable agriculture, salt accumulated in the root zone must be leached out. Therefore, if we consider leaching requirement, CWP of 50 mM treatment may not be higher than that of fresh water. In addition, higher NO₃⁻ uptake in freshwater treatment increased vegetative biomass and number of tillers per plant (Table 1), which had a competitive effect on the number of produced spikes [59]. The results imply that irrigation with more than 150 mM NaCl H₂O will result in zero yield. According to Hillel [36], water quality ranging between 34 and 86 mM NaCl is classified as moderately saline, while saline water ranged between 86 and 171 mM NaCl. This means that when freshwater resources are scarce, moderate saline water irrigation may be used to grow triticale by adopting appropriate practices for salt management.

4. Conclusions

This study evaluated the impact of irrigation water with different quality on crop growth and soil salinity build-up of the triticale when no leaching is applied. To evaluate the effect of water salinity on the soil–plant system, NaCl was used as the primary source of salinity. The results indicate that frequent applications of NaCl H₂O resulted in accumulation of salts in the soil profile, resulting in reduced water and NO₃⁻ uptake by plants. The application of 150 mM and 50 mM NaCl reduced grain yield by 97% and 42%. The highest crop water productivity was found for 50 mM NaCl treatment, followed by freshwater and 150 mM NaCl treatments, respectively. This shows that moderately saline water resources can be used to grow triticale in water scarce environments by adopting proper water and salt management approaches.