Fig. 2 A-D\u00a0The individual effect of urea-phosphate fertilizer rates (UPs) on 1\u2009A) SPAD reading, 1B) Plant height, 1\u2009C) leaf area, and 1D) leaf dry matter percentage (DrM%) of soybean plants cultivated in saline soil in both growth seasons 2022 and 2023, respectively. UP1, UP2, UP3, and UP4 represent urea-phosphate at 85.0, 107.0, 127, and 150.0\u00a0kg ha\u22121, respectively. The data are means\u00b1SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u2009\u2264\u20090.05 according to Duncan\u2019s multiple range test<\/p>\n Response of leaf nutrient contents in salt-stressed soybean plants to mgonp foliar application<\/p>\n Figure\u00a03<\/a> (A-D) graphically display the maximum values recorded in the leaves treated with MgONP2 in terms of SPAD readings (47.00 vs. 51.00 in 2022 and 2023, respectively), PH (64.08 vs. 67.57\u00a0cm in 2022 and 2023, respectively), and %DrM (56.63 vs. 55.81% in 2022 and 2023, respectively) in the first and second seasons. The highest LA values were achieved in the plants sprayed with MgONP1 (28.68 vs. 31.51\u00a0cm\u00b2 in the 2022 and 2023 growing seasons, respectively). In contrast, the minimum values in terms of the SPAD readings (43.72 vs. 47.25 in 2022 and 2023, respectively) and PH (57.50 vs. 54.32\u00a0cm in 2022 and 2023, respectively) were produced in the untreated plants (MONP0) in both seasons. In addition, the lowest LA (23.80 vs. 24.12\u00a0cm\u00b2 in 2022 and 2023, respectively) and DrM% (46.40 vs. 46.35% in 2022 and 2023, respectively) values in the 2022 and 2023 growth seasons were obtained in the plants treated with MgONP2 and MgONP1, respectively. Statistically, highly significant increases were recorded in the SPAD readings in 2022 and in the PH and LA values in 2023 following all the treatments. These treatments had no significant impacts on the PH or LA values in the first season or on the SPAD readings in the second season.<\/p>\n Fig. 3 A-D The individual effect of magnesium oxide nanoparticle doses (MgONPs) on (A) SPAD reading, B\u00a0Plant height, C\u00a0leaf area, and D\u00a0dry matter percentage of soybean plants cultivated in saline soil in both growth seasons 2022 and 2023, respectively. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u2009\u2264\u20090.05 according to Duncan\u2019s multiple range test<\/p>\n Response of growth\u2013physiological attributes in salt-stressed soybean plants to the interaction between soil-applied UP and foliar-applied MgONPs<\/p>\n The results, as observed in Table\u00a04<\/a>, demonstrate the enhanced impact of interaction between UP rates and MgONP doses on some growth and physiological traits. Similar findings were obtained for PH, LA, and DrM% in plants fertilized with UP3 and sprayed with MgONP2 (T32), plants treated with UP3 and foliarly sprayed with MgONP1 (T31), and plants fertilized with UP1 combined with MgONP2 (T12) treatments produced the maximum values in PH (81.33 vs. 83.37\u00a0cm), LA (44.92 vs. 54.63\u00a0cm\u00b2), and DrM% (65.41 vs. 62.51%) in the first and second seasons, respectively. Dissimilar data were recorded regarding the highest values in SPAD readings (53.25 vs. 83.37); however, in both seasons, the plants treated with T12 and T32 produced the best results. On the hand, the minimum values in PH (44.00\u00a0cm) in the second seasons and in SPAD readings (39.46) in the first season were obtained in plants fertilized with UP1 combined with MgONP1 (T11). Meanwhile, plants treated with UP2 and MgONP1 (T21) produced the lowest %DrM (38.33 and 38.40%) in both seasons. In addition, the lowest values in LA (15.65\u00a0cm\u00b2) in the 2022 season and in SPAD readings (40.00) in the 2023 season were recorded in plants fertilized with UP1 only, without using MgONP (T10). Furthermore, applying UP4 with MgONP (T42) was the least impactful on LA in the second season. There were highly significant differences among the treatments in SPAD readings in the first season and in LA in the second season. Non-significant differences were observed in SPAD readings in the second season, in LA in the first season, as well as in PH and %DrM in both seasons.<\/p>\n Table 4 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the growth-physiological attributes of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Leaf nutrient contentResponse of leaf nutrient content in salt-stressed soybean plants to UP soil application<\/p>\n The results, as graphically presented in Fig.\u00a04<\/a>(A-E), indicated that UP4 was the best application rate for soybean leaf nitrogen (LNC), phosphorus (LPC), potassium (LKC), calcium (LCaC), and magnesium (LMgC). However, this treatment produced the maximum values of 4.88 vs. 3.70% for LNC, 0.48 vs. 0.45% for LPC, 3.56 vs. 3.11% for LKC, 0.63 vs. 0.65% for LCaC, and 0.30 vs. 0.32% for LMgC in the first and second seasons, respectively. In addition, the plant leaves fertilized with UP1 and UP2 recorded the highest leaf sodium values (LNaC), recording 0.04% in both seasons, respectively. In contrast, the lowest leaf contents of N (4.18 vs. 3.00%), P (0.31 vs. 0.30%), Ca (0.49 vs. 0.50%), and Mg (0.22 vs. 0.20%) were recorded in plants fertilized with UP1 and UP2 in the 2022 and 2023 growth seasons, respectively. Moreover, UP2 and UP1 for LKC as well as UP4 and UP3 for LNaC, were the least impactful, demonstrating 2.75 vs. 2.30% and 0.03 vs. 0.02% for both elements in both seasons, respectively. For all the UP rates tested, highly significant differences were obtained for the above-mentioned nutrients, except for LNaC, which had a non-significant effect in both seasons.<\/p>\n Fig. 4 A-E The individual impact of urea-phosphate types (UPs) on leaf macronutrients content; (3A) nitrogen (LNC), (3B) phosphorus (LPC), (3C) potassium (LKC), (3D) calcium (LCaC), and (1E) magnesium (LMgC) of soybean plants cultivated in saline soil in two growing seasons 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n As seen in Fig.\u00a05<\/a>(A-D), the results related to the impact of UP fertilizer rates on the content of leaf micronutrients, such as iron (LFeC), manganese (LMnC), zinc (LZnC), and copper (LCuC), demonstrated that the plants fertilized with UP4 produced the maximum content of Mn (70.42 vs. 72.43\u00a0mg kg\u22121) in both seasons and of LZnC (36.77\u00a0mg kg\u22121) in the second season. Meanwhile, the plants treated with UP2 produced the highest LCuC (25.00 vs. 23.65\u00a0mg kg\u22121) in both growing seasons and the highest LFeC in the second season (113.72\u00a0mg kg1). Furthermore, UP was the most influential on LFeC (114.33\u00a0mg kg\u22121) and LZnC (35.99\u00a0mg kg\u22121) in the first season. On the contrary, UP3 were the least impactful, demonstrating the minimum values in LMnC (47.33 vs. 48.22\u00a0mg kg\u22121 and LCuC (15.30 vs. 13.15\u00a0mg kg\u22121) in both growing seasons, respectively, and the minimum value in LFeC (93.30\u00a0mg kg\u22121) in the first season. The lowest LZnC (31.86 vs. 32.82\u00a0mg kg\u22121 in 2022 and 2023, respectively) was obtained in plants treated with UP2 in both growth seasons. Statistically, highly significant differences were found for LFeC, LMnC, and LCuC; moreover, non-significant effects were found for LZnC in both growth seasons.<\/p>\n Fig. 5 A-D The individual impact of urea-phosphate rates (UPs) on leaf micronutrients content; (4A) iron (LFeC), (4B) manganese (LMnC), (4\u00a0C) zinc (LZnC), and (4D) copper (LCuC) of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u2009\u2264\u20090.05 according to Duncan\u2019s multiple range test<\/p>\n Response of leaf nutrient content in salt-stressed soybean plants to MgONPs foliar application<\/p>\n The impact of the application of MgONP doses on the leaf contents of the aforementioned macronutrients in the 2022 and 2023 seasons are graphically presented in Fig.\u00a06<\/a>(A-E). Similar findings were obtained for LPC, LCaC, and LMgC. The MgONP doses, ranked in descending order in terms of MgONP2\u2009>\u2009MgONP1\u2009>\u2009MgONP0, were 0.47\u2009>\u20090.41\u2009>\u20090.35 and 0.43\u2009>\u20090.37\u2009>\u20090.32 for LPC, 0.62\u2009>\u20090.56\u2009>\u20090.51 and 0.63\u2009>\u20090.58\u2009>\u20090.63 for LCaC, and 0.31\u2009>\u20090.27\u2009>\u20090.22 and 0.30\u2009>\u20090.26\u2009>\u20090.20 for LMgC in each growth season, respectively. With regard to LNaC, the doses of MgONPs were arranged in the following order (for MgONP0\u2009>\u2009MgONP1\u2009>\u2009MgONP2): 0.04\u2009>\u20090.03\u2009>\u20090.02 and 0.04\u2009>\u20090.04\u2009>\u20090.03 in the 2022 and 2023 growing seasons, respectively. Dissimilar results were achieved in both growth seasons for LNC and LKC. However, the results for treatment with MgONPs were ranked as, in descending order, MgONP2 (4.58%)\u2009>\u2009MgONP0 (4.47%)\u2009>\u2009MgONP1 (4.42%) and MgONP2 (3.55%)\u2009>\u2009MgONP1 (3.35%)\u2009>\u2009MgONP0 (3.15%) for LNC and as MgONP1 (3.23%)\u2009>\u2009MgONP2 (3.19%)\u2009>\u2009MgONP0 (3.09%) and MgONP2, (2.83%)\u2009>\u2009MgONP1 (273%)\u2009>\u2009MgONP0 (2.63%) for LKC in the 2022 and 2023 seasons, respectively.<\/p>\n Fig. 6 A-E The individual impact of magnesium oxide nanoparticle doses (MgONPs) on leaf macronutrients content; (3A) nitrogen (LNC), (3B) phosphorus (LPC), (3C) potassium (LKC), (3D) calcium (LCaC), and (1E) magnesium (LMgC) of soybean plants cultivated in saline soil in two growing seasons 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n The results obtained from the ANOVA showed that MgONPs had highly significant influences on the leaf content of P, Ca, and Mg in both seasons, of LNC and LKC in the 2023 season, and of LNC in the 2022 season. Non-significant differences were found for LNC and LKC in the first season. The results depicted in Fig.\u00a07<\/a>(A-D) document the effect of treatment with different MgONPs on the micronutrient contents of soybean leaves during the 2022 and 2023 seasons.<\/p>\n Fig. 7 A-D The individual impact of magnesium oxide nanoparticle doses (MgONPs) on leaf micronutrients content; (6A) iron (LFeC), (6B) manganese (LMnC), (6C) zinc (LZnC), and (6D) copper (LCuC) of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n The statistical analysis revealed that MgONPs did not have a significant impact on LFeC and had highly significant influences on LMnC, LZnC, and LCuC in both growth seasons. The obtained results demonstrated that the highest LMnC values (63.84 vs. 64.75\u00a0mg kg\u22121) were produced in untreated plants. Meanwhile, the plants treated with MgONP2 and MgONP1 produced the maximum LFeC in two growing seasons. Regarding the highest values of LZnC and LCuC, our results noted that MgONP1 for LZnC and MgONP2 for LCuC were the most impactful, producing levels of 38.89 vs. 38.12\u00a0mg kg1 and 23.08 vs. 22.10\u00a0mg kg\u22121 in the 2022 and 2023 seasons, respectively. On the contrary, the lowest LFeC (100.64 vs. 103.04\u00a0mg kg\u22121) and LCuC (16.91 vs. 17.26 mg kg\u22121) were obtained in untreated plants. Furthermore, the least influence of fertilizer on LMnC and LZnC levels was found in plants fertilized with MgONP1 and MgONP2, respectively; the minimum values in both growing seasons were recorded in these plants.<\/p>\n Response of leaf nutrient content in salt-stressed soybean plants to the interaction between soil-applied UP and foliar-applied MgONPs<\/p>\n Despite the improvements obtained due to the interactive impact between UP and MgONP, the results obtained from the statistical analysis indicated that there were no significant effects on all the macronutrients studied. The finding obtained from our field study highlighted the pivotal influence of using maximum rates of both UP and MgONP5, as listed in Table\u00a05<\/a>. More clearly, the maximum contents of N (5.52 vs. 3.90% in the 2022 and 2023 seasons, respectively), P (0.54 vs. 6.50% in the 2022 and 2023 seasons, respectively), Ca (0.67 vs. 0.70% in the 2022 and 2023 seasons, respectively), and Mg (0.36 vs. 0.34% in the 2022 and 2023 seasons, respectively) were recorded in soybean plants fertilized with UP4 and foliarly sprayed with MgONP2. Similarly, plants treated T20 produced the highest values in Na (0.05 vs. 0.04% in 2022 vs. 2023) in both seasons. For LKC, dissimilar results were produced among both growth seasons, as the highest values of K were found in the leaves of plants treated with T41 (3.64%) in the first season and in those treated with T42 (3.20%) in the second season. As for the lowest values obtained, the results were completely different. However, the T20 treatment was the least influential for LCaC (0.44 vs. 0.45%), LMgC (0.20 vs. 0.19%), and LPC (0.29 vs. 0.25%) in both growing seasons and for LNC (2.80%) and LKC (2.20%) in the second season. Furthermore, the application of T21 produced the lowest values in LNC (3.70%) and LKC (2.66%) in the first season, while plants treated with T42 produced the minimum LNaC values (0.01 vs. 0.02% in the 2022 and 2023 growth seasons, respectively). It is clear from Table\u00a06<\/a> that the interaction between UP and MgONP significantly affected the leaf micronutrient content in soybean plants. The obtained results indicated that the application of T20 and T10 treatments was the most influential on LFeC (140.01 vs. 144.71\u00a0mg kg\u22121) and LMnC (93.43 vs. 96.87\u00a0mg kg\u22121) in the 2022 and 2023 seasons, respectively. Dissimilar results were found for LZnC and LCuC during both growth seasons. However, the maximum values in LZnC (52.32 vs. 51.75\u00a0mg kg\u22121) were produced in plants treated with T31 and T11. Likewise, the plants treated with T12 and T11 demonstrated the highest LCuC values (30.00 vs. 29.42\u00a0mg kg\u22121) in both seasons. In spite of the clear variation in the best values obtained, the values associated with the lowest were similar to each other. However, the plants treated with T40, T32, and T31 demonstrated the lowest values in Fe (53.24 vs. 51.50\u00a0mg kg\u22121), Mn (22.80 vs. 21.68\u00a0mg kg\u22121), and Cu (19.20 vs. 8.20\u00a0mg kg\u22121) in the first and second seasons. The application of T30, and T12 treatments was the least impactful on LZnC levels of 22.27 and 21.37\u00a0mg kg\u22121 were recorded in the 2022 and 2023 seasons, respectively.<\/p>\n Table 5 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the leaf macronutrient contents of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Table 6 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the leaf micronutrient contents of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Seeds\u2019 mineral compositionsResponse of mineral seed composition in salt-stressed soybean plants to UP soil application<\/p>\n Figure\u00a08<\/a>(A-E) present the influences of the application of the different rates of UP as a soil fertilizer on the macronutrient contents of the seeds in the 2022 and 2023 seasons. According to the results, there was no noticeable benefit from adding any particular treatment over the others. However, the plants fertilized at UP1 produced the maximum seed nitrogen (SNC) and calcium (SCaC) contents, recording 6.62% and 0.40%, respectively, in the 2022 season, as well as a seed potassium content (SKC) of 1.78% in the 2023 season. In addition, UP\u2083 was the most impactful rate for the seed magnesium content (SMgC), which was recorded as 0.43% in the first season, and for the seed phosphorus (SPC) (0.61%) and SCaC (0.34%) in the second season. Meanwhile, UP4 was the superior rate, producing the maximum SKC value (1.71%) in the first season, as well as the highest SNC (6.46%) and SMgC (0.42%) values in the second season.<\/p>\n Fig. 8 A-E\u00a0The individual impact of urea-phosphate types (UPs) on seed macronutrients content; (8A) nitrogen (SNC), (8B) phosphorus (SPC), (8C) potassium (SKC), (8D) calcium (SCaC), and (8E) magnesium (SMgC) of soybean plants cultivated in saline soil in two growing seasons 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n In contrast, UP\u2082 was the least influential for the SMgC (0.35 vs. 0.33%) contents in both growth seasons, as well as for the SNC (5.66%) and SKC (1.50%) in the first season and the SPC (0.56%) in the second season. The lowest SNC (5.83%) and SCaC (0.22%) values were obtained in the plants treated at UP1 in the second season. Furthermore, the application of UP4 produced the minimum SPC (0.60%) and SCaC (0.29%) values in the first season. The results obtained from the ANOVA indicated that all the treatments had highly significant influences on the SNCs, SKCs, SCaCs, and SMgCs; in addition, significant effects on the SPCs were observed in both seasons. The results presented in Fig.\u00a09<\/a>(A-D) reveal the beneficial effect that UP\u2082 exerted on the micronutrient contents of the seeds. The highest iron (SFeC) and zinc (SZnC) contents were recorded in both growing seasons (78.39 vs. 77.48\u00a0mg kg\u207b\u00b9 for the SFeC and 36.44 vs. 34.82\u00a0mg kg\u207b\u00b9 for the SZnC in 2022 and 2023, respectively). Moreover, the maximum seed manganese contents (SMnCs) were recorded in the plants fertilized at UP4 (42.45 vs. 43.55\u00a0mg kg\u207b\u00b9 in 2022 and 2023, respectively). Dissimilar findings were obtained for the seed copper contents (SCuCs); however, the highest values were produced as a result of applying UP2 and UP3 in both seasons, 2022 and 2023, respectively. In contrast, the UP1 application was the least influential; the minimum SFeC (69.25 vs. 65.26\u00a0mg kg\u207b\u00b9), SMnC (26.56 vs. 25.03\u00a0mg kg\u207b\u00b9), and SCuC (10.71 vs. 10.98\u00a0mg kg\u207b\u00b9) values were recorded in the plants treated at UP1 in both growth seasons, respectively. Meanwhile, the lowest SZnC values were achieved in the plants treated at UP4 (25.00 vs. 25.69\u00a0mg kg\u207b\u00b9 in 2022 and 2023, respectively). Statistically, all the treatments had significant impacts (at p\u2009\u2264\u20090.01) for all the aforementioned micronutrients in the first and second seasons.<\/p>\n Fig. 9 A-D\u00a0The individual impact of urea-phosphate rates (UPs) on seed micronutrients content; (9A) iron (SFeC), (9B) manganese (SMnC), (9C) zinc (SZnC), and (9D) copper (SCuC) of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n Response of mineral seed composition in salt-stressed soybean plants to MgONPs foliar application<\/p>\n The results obtained from the statistical analysis indicated that all MgONPs treatments had significant impacts (at p\u2009\u2264\u20090.01) on all studied macronutrient content levels in both growth seasons. As graphically presented in Fig.\u00a010<\/a>(A-E), the greatest improvements in the macronutrient content of leaves were closely associated with the application of MgONP1 and MgONP2 treatments, whereas the maximum values in SNC (6.40 vs. 6.35%) in both seasons, as well as in SPC (0.66%) in the first season and in SKC (1.68%) and SMgC (0.38%) in the second season were achieved in soybean plants that were foliar applied with MgONP1. Furthermore, the highest values in SCaC (0.40 vs. 0.33%) in both growing seasons and the highest value in SMgC (0.42%) in the 2022 season and in SPC (0.66%) in the 2023 season were achieved in plants treated with MgONP\u2082. The highest SKC value (1.75) in the first season was obtained in untreated plants. Conversely, the lowest values in SNC (6.25 vs. 6.07%), SPC (0.56 vs. 051%), SCaC (0.33 vs. 0.26), and SMgC (0.36 vs. 6.34%) were obtained in untreated plants (MgONP0). Dissimilar findings were produced regarding SKC, as the minimum values were recorded as a result of MgONP1 in the first season and as a result of MgONP2 in the second season.<\/p>\n Fig. 10 A-E\u00a0The individual impact of magnesium oxide nanoparticle doses (MgONPs) on seed macronutrients content; (10A) nitrogen (SNC), (10B) phosphorus (SPC), (10C) potassium (SKC), (10D) calcium (SCaC), and (10E) magnesium (SMgC) of soybean plants cultivated in saline soil in two growing seasons 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n The results presented in Fig.\u00a011<\/a>(A-D) reveal that following the application of MgONPs as a foliar application, the levels of micronutrients in the leaves of all studied plants significantly improved. The results indicated that for SFeC and SMnC, the MgONP doses, in descending order, were ranked as follows: MgONP1\u2009>\u2009MgONP0\u2009>\u2009MgONP2, recording 84.41\u2009>\u200969.41\u2009>\u200965.68\u00a0mg kg\u22121 vs. 84.03\u2009>\u200968.20\u2009>\u200963.95\u00a0mg kg\u22121 for SFeC and 36.55\u2009>\u200936.01\u2009>\u200930.40\u00a0mg kg\u22121 vs. 36.98\u2009>\u200935.64\u2009>\u200931.56\u00a0mg kg\u22121 for SMnC in both seasons, respectively. Similarly, for SZnC, the MgONP doses were ranked in descending order as follows: MgONP2 (34.09 vs. 34.36\u00a0mg kg\u22121)\u2009>\u2009MgONP1 (30.21 vs. 30.13\u00a0mg kg\u22121)\u2009>\u2009MgONP0 (28.34 vs. 26.90\u00a0mg kg\u22121) in 2022 and 2023, respectively. Meanwhile, the MgONP doses can be arranged in descending order as MgONP1 (15.16 vs. 14.67\u00a0mg kg\u22121)\u2009>\u2009MgONP2 (12.33 vs. 12.76\u00a0mg kg\u22121)\u2009>\u2009MgONP0 (10.03 vs. 10.75\u00a0mg kg\u22121) for SCuC in both growth seasons, respectively. The statistical analysis identified highly significant influences of MgONP doses on all studied leaf contents of micronutrients.<\/p>\n Fig. 11 A-D\u00a0The individual impact of magnesium oxide nanoparticle doses (MgONPs) on seed micronutrients content; (11A) iron (SFeC), (11B) manganese (SMnC), (11C) zinc (SZnC), and (11D) copper (SCuC) of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n Response of mineral seed composition of salt-stressed soybean plants to the interaction between soil-applied UP and foliar-applied MgONPs<\/p>\n The data presented in Table\u00a07<\/a> indicate that all studied leaf macronutrient content levels were markedly enhanced as a result of interaction between UP fertilizer rates and MgONP doses. Our investigation demonstrated that the highest values (6.92 vs. 6.96%) in SNC in both growing seasons and in SKC (2.01%) in the second season were recorded in plants fertilized with the T41 treatment. In addition, the maximum values in SPC (0.70%) and SMgC (0.50%) in the second season were associated with the application of T42. Furthermore, the plants treated with T21 produced the highest values in SPC (0.71%) and SCaC (0.47%) in the first season. Moreover, the use of the T30 treatment was the most significant for LKC (2.01%) and LMgC (0.46%) levels in the first season. Dissimilar results were obtained regarding the lowest values in seed macronutrient contents, as the plants treated with T40 demonstrated the minimum values in SNC (5.51%) and LPC (0.52%) in the first season, while the plants fertilized with T10 demonstrated the lowest mean values for SCaC (0.21%) and for SMgC (0.31%) in the second season. In addition, the application of T12, T30, and T31 produced the minimum values in SNC (5.55%), SPC (0.50%), and SKC (1.02%), respectively in the second season. The analysis of variance indicating that all interaction treatments had highly significant effects on all aforementioned levels of macronutrient content. According to the results listed in Table\u00a08<\/a>, the highest values in SFeC (95.02. vs. 98.88\u00a0mg kg\u22121) in both seasons and the highest levels of SMnC (50.00\u00a0mg kg\u22121) in the 2022 season and of SCuC (19.75\u00a0mg kg\u22121) in the 2023 season were achieved in the plants fertilized with T41. Furthermore, the maximum SZnC (38.91\u00a0mg kg\u22121) and SCuC (19.87\u00a0mg kg\u22121) was recorded during the first season in plants treated with T22. The application of T32 was the most impactful on SMnC (49.53\u00a0mg kg\u22121) and SZnC (42.24\u00a0mg kg\u22121) in the second season. On the other hand, the lowest values in SMnC (18.57 vs. 16.87\u00a0mg kg\u207b\u00b9) and SCuC (5.00 vs. 5.89\u00a0mg kg\u207b\u00b9) in 2022 and 2023, respectively were obtained in plants treated with T\u2081\u2082 and T\u2082\u2080. Meanwhile, the plants fertilized with T42 demonstrated the lowest value in SFeC (55.33\u00a0mg kg\u207b\u00b9) in the second season and in SZnC (20.72\u00a0mg kg\u207b\u00b9) in the first season. Moreover, the application of T30 and T\u2081\u2080 produced the lowest values in SFeC (54.49\u00a0mg kg\u207b\u00b9) in the first season and in SZnC (20.17\u00a0mg kg\u207b\u00b9) in the second season.<\/p>\n Table 7 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the seed macronutrient contents of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Table 8 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the seed micronutrient contents of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Yield and its attributesResponse of yield and its attributes of salt-stressed soybean plants to UP soil application<\/p>\n \n The results obtained from the ANOVA clearly indicated that all UP treatments had highly significant effects on 100-seed weight (HSW), seed oil content (SOC), seed protein content (SPC), and total seed yield (TSY) in both growth seasons. As visually evident in Fig.\u00a012<\/a>(A-D), the highest values in SOC (20.09 vs. 20,18%) were produced in plants fertilized with UP3 in both growing seasons. Meanwhile, the maximum values in HSW (17.82 vs. 17.60\u00a0g) and TSY (4.66 vs. 4.87ton ha\u22121) in the 2022 and 2023 seasons, respectively were obtained in plants treated with UP4. Although UP4 had a profound impact on SPrC in the second season, the use of UP1 produced the highest value in the first season. Similarly, the lowest values in HSW (15.06 vs. 15.08\u00a0g) and TSY (3.82 vs. 4.01ton ha\u22121) were obtained in plants treated with UP2, while the application of UP1 produced the lowest SOC (19.26%) in the first season and the lowest SPC (36.45%) in the second season. Simultaneously, the use of UP2 produced the minimum values in SPrC (35.39%) in the first season and the minimum value in SOC (19.49%) in the second season.<\/p>\n Fig. 12 A-D\u00a0The individual impact of urea-phosphate rates (UPs) on (12A) SOC, (12B) SPrC, (12C) HSW, and (12D) TSY of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n Response of yield and its attributes of salt-stressed soybean plants to MgONPs foliar application<\/p>\n The results obtained from the statistical analysis indicated that MgONPs treatments significantly (at p\u2009\u2264\u20090.01) affected yield and its components. As graphically demonstrated in Fig.\u00a013<\/a>(A-D), the plants foliarly sprayed with MgONP2 produced the maximum values in SOC (19.79 vs. 19.91%) and TSY (4.55 vs. 4.74ton ha\u22121) in the first and second seasons. Furthermore, the highest SPrC values (40.03 vs. 39.69%) were produced in plants treated with MgONP1. Moreover, the highest values in HSW (17.38 vs. 17.04\u00a0g) were recorded in untreated plants in both growth seasons. On the other hand, MgONP2 treatment was the least influential on HSW, producing HSW levels of 16.29 vs. 16.23\u00a0g in the two growing seasons. Meanwhile, the lowest values in SPrC (39.05 vs. 37.96%), TSY (3.89 vs. 4.00ton ha\u22121), and SOC (19.35 vs. 19.54%) in the 2022 and 2023 seasons, respectively were obtained in untreated plants.<\/p>\n Fig. 13 A-D\u00a0The individual impact of magnesium oxide nanoparticles doses (MgONPs) on (13A) SOC, (13B) SPrC, (13C) HSW, and (13D) TSY of soybean plants cultivated in saline soil in the 2022 and 2023 growing seasons. The data are means \u00b1 SE (Standard Error) for three replicates. Means value that have different lower-case letter in each season are significant at p\u22640.05 according to Duncan\u2019s multiple range test<\/p>\n Response of yield and its attributes of salt-stressed soybean plants to the interaction between soil-applied UP and foliar-applied MgONPs<\/p>\n The data explored in Table\u00a09<\/a> indicate that plants treated with both UP as a soil application and MgONPs as a foliar spray, irrespective of their doses, markedly outperformed the control treatment, in terms of enhanced productivity and yield-related attributes, although the ANOVA data revealed that all treatments had significant influences (at p\u2009\u2264\u20090.01) on the HSW, SOC, and SPC. Conversely, there were no significant impacts on TSY in both growth seasons, respectively. We found that the co-application of UP4 and MgONP1 (T41) was the superior treatment; it produced the maximum values for HSW (18.77 vs. 18.53\u00a0g) and for SPrC (43.25 vs. 43.48%) in both growing seasons. Meanwhile, the T42 treatment was the most impactful on TSY, producing the highest values (5.00 vs. 5.19ton ha\u22121) in both seasons, respectively. Dissimilar results were obtained for SOC; however, T31 and T40 produced the best values (20.75 vs. 21.02%) in the 2022 and 2023 seasons, respectively. Conversely, the lowest values in HSW (13.27 vs. 13.00\u00a0g) and TSY (3.54 vs. 3.62 tan ha\u22121) in the first and second seasons, respectively were produced in plants treated with T22 and T20. Interestingly, the application of T40 and T12 for SPrC and T11 and T41 for SOC were the least impactful, producing the minimum values for SPrC (34.42 vs. 34.67%) and SOC (18.40 vs. 18.56%) in the two growing seasons, respectively.<\/p>\n Table 9 Impact of the interaction between urea-phosphate (UP) as a soil application and magnesium oxide nanoparticles (MgONPs) as a foliar nourishment on the yield and its components of soybean plants cultivated in saline-sodic soil during two consecutive seasons (2022 and 2023)Principal component, pearson\u2019s correlation, and stepwise multiple regression analyses<\/p>\n Principal component, Pearson\u2019s correlation, and stepwise multiple regression analyses were performed on the physiological\u2013growth attributes, leaf nutrient contents, and yield- and quality-related parameters of soybean plants cultivated in saline\u2013sodic soil. Principal component analysis (PCA) was performed to evaluate the relations between the UP x MgNP interaction treatments and the abovementioned characteristics. As shown in Fig.\u00a014, the PCA indicated that the first two main components, Dim 1 and Dim 2 (PCA-diminution 1 and -diminution 2, respectively), accounted for 48.7% of the total variation. PC1 interpreted 32.5% of the variation. The nearby vectors of the measured parameters presented a positive correlation with one another. However, the SPAD readings, PH, LA, LMgC, SPC, SCaC, SOC, and TSY fell under the same group, while the LNC, LPC, LKC, LCaC, LMnC, SNC, SMgC, SPrC, and HSW were in a separate group.<\/p>\n Fig. 14 Principal component analysis (PCA) of applied urea\u2013phosphate (UP) and magnesium oxide nanoparticle (MgONP) treatments and studied parameters. Each black dot denotes a treatment. SPAD, PH, LA, and DrM indicate the relative chlorophyll content, plant height, leaf area, and dry matter percentage, respectively. LNC, LPC, LKC, LCaC, LMgC, LFeC, LMnc, LZnC, and LCuC indicate the leaf nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, and copper contents, respectively. SNC, SPC, SKC, SCaC, SMgC, SFeC, SMnC, SZnC, and SCuC indicate the seed nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, and copper contents, respectively. SOC, SPrC, and TSY indicate the seed oil content, protein content, and total seed yield, respectively. Values are based on averages of two consecutive seasons (2022 and 2023). T10, T11, and T12 represent the UP applied at 85.0 kg ha\u22121 with three doses of MgONPs: 0.00, 50.0, and 100.0 mg L\u22121, respectively. T20, T21, and T22 represent the UP applied at 107.0 kg ha\u22121 with three doses of MgONPs: 0.00, 50.0, and 100.0 mg L\u22121, respectively. T30, T31, and T32 represent the UP applied at 127.0 kg ha\u22121 with three doses of MgONPs: 0.00, 50.0, and 100.0 mg L\u22121, respectively. T40, T41, and T42 represent the UP applied at 85.0 kg ha\u22121 with three doses of MgONPs: 0.00, 50.0, and 100.0 mg L\u22121, respectively<\/p>\n The PCA biplot in Fig.\u00a013<\/a> shows that the SPAD, PH, LA, LMgC, SPC, SCaC, and SOC were improved by T12, T31, and T32. Moreover, the LNC, LPC, LKC, LCaC, LMnC, HSW, DrM, SNC, SMnC, and SPrC were also enhanced by T41 and T42. Therefore, the application of UP and MgONP interaction plays a crucial role in promoting most of the traits associated with the nutritional status, yield, and their components.<\/p>\n![\"figure](\"https:\/\/www.newsbeep.com\/il\/wp-content\/uploads\/2025\/10\/12870_2025_7445_Fig2_HTML.png\")
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