Author Contributions
Conceptualization, H.S.E.-B., E.G.S., W.F.S. and A.A.A.; methodology, S.A.I., E.G.S., N.M.I., W.F.S., A.A.A. and H.S.G.; software, E.G.S. and N.M.I.; validation, H.S.E.-B., E.G.S. and M.M.E.-M.; formal analysis, E.G.S., W.F.S., A.A.A. and H.S.G.; investigation, H.S.E.-B., M.M.E.-M. and E.G.S.; resources, E.G.S. and N.M.I.; data curation, H.S.E.-B., E.G.S. and E.G.S.; writing—original draft preparation, E.G.S.; funding, H.S.E.-B., W.F.S., A.A.A. and H.S.G.; writing—review and editing, H.S.E.-B., M.M.E.-M. and E.G.S.; visualization, E.G.S.; supervision, H.S.E.-B., E.G.S., S.A.I., N.M.I., M.M.E.-M. and S.A.I. All authors have read and agreed to the published version of the manuscript.
Figure 1.
The experimental treatments and design. Different plant treatments are identified by horizontal lines as follows: 100% WHC + TR (0 ppm) control, 100% WHC + TR (0.5 ppm), 100% WHC + TR (1 ppm), 80% WHC + TR (0 ppm), 80% WHC + TR (0.5 ppm), 80% WHC + TR (1 ppm), 40% WHC + TR (0 ppm), 40% WHC + TR (0.5 ppm), and 40%WHC + TR (1 ppm).
Figure 1.
The experimental treatments and design. Different plant treatments are identified by horizontal lines as follows: 100% WHC + TR (0 ppm) control, 100% WHC + TR (0.5 ppm), 100% WHC + TR (1 ppm), 80% WHC + TR (0 ppm), 80% WHC + TR (0.5 ppm), 80% WHC + TR (1 ppm), 40% WHC + TR (0 ppm), 40% WHC + TR (0.5 ppm), and 40%WHC + TR (1 ppm).
Figure 2.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) stomata conductance in 2020 and 2021, (C,D) transpiration rate in 2020 and 2021, (E,F) photosynthesis in 2020 and 2021, and (G,H) water use efficiency in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 2.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) stomata conductance in 2020 and 2021, (C,D) transpiration rate in 2020 and 2021, (E,F) photosynthesis in 2020 and 2021, and (G,H) water use efficiency in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 3.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) fruit weight in 2020 and 2021 and (C,D) number of fruits per plant in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 3.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) fruit weight in 2020 and 2021 and (C,D) number of fruits per plant in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 4.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) total yield per plant (g) in 2020 and 2021, (C,D) early yield (kg·m−2) in 2020 and 2021, and (E,F) total yield (ton·hec−1) in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 4.
Effects of the interaction between water irrigation levels and foliar application with TR interaction on (A,B) total yield per plant (g) in 2020 and 2021, (C,D) early yield (kg·m−2) in 2020 and 2021, and (E,F) total yield (ton·hec−1) in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 5.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) vitamin C during 2020 and 2021 seasons, respectively, (C,D) anthocyanin during 2020 and 2021 seasons, respectively, and (E,F) acidity during 2020 and 2021 seasons, respectively. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 5.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) vitamin C during 2020 and 2021 seasons, respectively, (C,D) anthocyanin during 2020 and 2021 seasons, respectively, and (E,F) acidity during 2020 and 2021 seasons, respectively. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 6.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) N% in leaves of strawberry in 2020 and 2021, (C,D) P% in leaves in 2020 and 2021, and (E,F) K% in leaves of strawberry in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 6.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) N% in leaves of strawberry in 2020 and 2021, (C,D) P% in leaves in 2020 and 2021, and (E,F) K% in leaves of strawberry in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 7.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) APX in leaves in 2020 and 2021, (C,D) CAT in leaves in 2020 and 2021, (E,F) POD in leaves in 2020 and 2021, (G,H) SOD in leaves in 2020 and 2021, and (I,J) proline in leaves in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 7.
Effects of water irrigation levels and foliar application with TR interaction on (A,B) APX in leaves in 2020 and 2021, (C,D) CAT in leaves in 2020 and 2021, (E,F) POD in leaves in 2020 and 2021, (G,H) SOD in leaves in 2020 and 2021, and (I,J) proline in leaves in 2020 and 2021. Vertical bars represent standard errors of the mean; in each bar, values followed by different letters differ significantly at p = 0.05 according to the LSD test.
Figure 8.
Biplot of the first two principal components for the morphological, yield, and physiochemical traits of strawberry plants. The morphological parameters comprised plant height and number of leaves per plant. The yield parameters included fruit weight and total yield. The fruit quality parameters included vitamin C, total soluble solids (TSS%), acidity, and firmness. The physiological traits included photosynthesis and transpiration rate. The physiochemical parameters comprised total nitrogen (N), phosphorus (P), potassium (K), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and proline. Red circle symbols represent the different water regimes and TR treatments; 100% WHC + TR (0 ppm) control, 100% WHC + TR (0.5 ppm), 100% WHC + TR (1 ppm), 80% WHC + TR (0 ppm), 80% WHC + TR (0.5 ppm), 80% WHC + TR (1 ppm), 40% WHC + TR (0 ppm), 40% WHC + TR (0.5 ppm), 40%WHC + TR (1 ppm).
Figure 8.
Biplot of the first two principal components for the morphological, yield, and physiochemical traits of strawberry plants. The morphological parameters comprised plant height and number of leaves per plant. The yield parameters included fruit weight and total yield. The fruit quality parameters included vitamin C, total soluble solids (TSS%), acidity, and firmness. The physiological traits included photosynthesis and transpiration rate. The physiochemical parameters comprised total nitrogen (N), phosphorus (P), potassium (K), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and proline. Red circle symbols represent the different water regimes and TR treatments; 100% WHC + TR (0 ppm) control, 100% WHC + TR (0.5 ppm), 100% WHC + TR (1 ppm), 80% WHC + TR (0 ppm), 80% WHC + TR (0.5 ppm), 80% WHC + TR (1 ppm), 40% WHC + TR (0 ppm), 40% WHC + TR (0.5 ppm), 40%WHC + TR (1 ppm).
Figure 9.
Graphical chart explains the effect of three levels of TR on physiological and biochemical response of strawberry plants under normal and drought stress conditions.
Figure 9.
Graphical chart explains the effect of three levels of TR on physiological and biochemical response of strawberry plants under normal and drought stress conditions.
Table 1.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2020/2021.
Table 1.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2020/2021.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WHC | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Plant Height (cm) | Number of Leaves |
---|
0 ppm TR | 12.43 e | 19.67 b | 9.0 g | 13.70 c | 9.667 de | 15.33 b | 6.67 f | 10.56 c |
0.5 ppm TR | 17.67 c | 11.00 f | 15.53 d | 14.73 b | 16.33 b | 8.0 ef | 11.0 cd | 11.78 b |
1 ppm TR | 28.00 a | 17.60 c | 18.33 c | 21.31 a | 18.33 a | 12.67 c | 12.67 c | 14.56 a |
Mean | 19.37 a | 16.09 b | 14.29 c | | 14.78 a | 12.00 b | 10.11 c | |
LSD 0.05 | | | | | | | | |
IR | 0.7 | | | | 1.0 | | | |
TR | 0.73 | | | | 1.1 | | | |
IR XTR | 1.3 | | | | 1. 9 | | | |
Treatments | Leaf Area (cm2) | Chlorophyll (SPAD) Reading |
0 ppm TR | 44.00 d | 56.33 b | 31.67 f | 44.00 c | 30.33 b | 29.67 bc | 27.3 d | 29.11 b |
0.5 ppm TR | 58.00 b | 40.67 e | 44.33 d | 47.67 b | 31.33 b | 30.67 b | 28.0 cd | 30.00 b |
1 ppm TR | 62.00 a | 50.67 c | 50.33 c | 54.33 a | 36 a | 30.67 b | 29.33 bcd | 31.89 a |
Mean | 54.67 a | 49.22 b | 42.11 c | | 32.44 a | 30.33 b | 28.22 c | |
LSD 0.05 | | | | | | | | |
IR | 1.0 | | | | 1.16 | | | |
TR | 1.2 | | | | 1.2 | | | |
IR XTR | 2.2 | | | | 2.02 | | | |
Table 2.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2021/2022.
Table 2.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2021/2022.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WHC | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Plant Height (cm) | Number of Leaves |
---|
0 ppm TR | 11.77 d | 10.3 d | 8.3 e | 10.14 c | 9.333 d | 7.333 e | 6.333 e | 7.667 c |
0.5 ppm TR | 17.33 b | 14.20 c | 11.1 d | 14.0 b | 14.67 b | 11.67 c | 10.33 d | 12.22 b |
1 ppm TR | 20.33 a | 17.30 b | 15.20 c | 17.61 a | 17.33 a | 13.67 b | 12.00 c | 14.33 a |
Mean | 16.48 a | 13.94 b | 11.57 c | | 13.78 a | 10.89 b | 9.556 c | |
LSD.005 | | | | | | | | |
IR | 1.0 | | | | 0.73 | | | |
TR | 1.02 | | | | 1.0 | | | |
IR XTR | 1.7 | | | | 1.2 | | | |
Treatments | Leaf Area (cm2) | Chlorophyll (SPAD) Reading |
0 ppm TR | 42.0 d | 36.0 ef | 32.67 f | 36.89 c | 31.33 b–d | 29.67 d | 27.0 e | 29.33 b |
0.5 ppm TR | 51.3 b | 41.0 d | 37.0 e | 43.11 b | 32.67 b | 31. 7 b–d | 26.67 e | 30.33 b |
1 ppm TR | 60.0 a | 53.0 b | 46.0 c | 53.00 a | 35.67 a | 32.0 bc | 30.0 cd | 32.56 a |
Mean | 51.11 a | 43.3 b | 38.56 c | | 33.22 a | 31.11 b | 27.89 c | |
LSD.005 | | | | | | | | |
IR | 1.942 | | | | 1.239 | | | |
TR | 2.0 | | | | 1.239 | | | |
IR XTR | 3.363 | | | | 2.146 | | | |
Table 3.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2020/2021.
Table 3.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2020/2021.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WHC | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Shoot Fresh Weight (g) | Shoot Dry Weight (g) |
---|
0 ppm TR | 35.0 e | 27.0 f | 22.33 f | 28.11 c | 9.0 cd | 8.0 de | 6.667 e | 7.889 b |
0.5 ppm TR | 48.0 bc | 42.3 d | 33.67 e | 41.33 b | 13.07 a | 11.1 b | 10.67 bc | 11.61 a |
1 ppm TR | 51.3 ab | 53.3 a | 45.33 cd | 50.00 a | 13.07 a | 11.67 ab | 11.13 b | 11.96 a |
Mean | 44.8 a | 40.89 b | 33.78 c | | 11.71 a | 10.26 b | 9.489 b | |
LSD.005 | | | | | | | | |
IR | 0.64 | | | | 1.0 | | | |
TR | 2.792 | | | | 1.1 | | | |
IR XTR | 4.836 | | | | 1.94 | | | |
Treatments | Root Fresh Weight (g) | Root Dry Weight (g) |
0 ppm TR | 7.00 de | 6.0 e | 5.33 e | 6.11 c | 1.90 d | 1.033 e | 0.96 f | 1.30 c |
0.5 ppm TR | 10.67 b | 9.0 bc | 8.33 cd | 9.33 b | 3.00 b | 2.533 c | 2.23 cd | 2.589 b |
1 ppm TR | 13.00 a | 10.47 b | 10.10 b | 11.19 a | 3.900 a | 3.167 b | 3.133 b | 3.40 a |
Mean | 10.22 a | 8.489 b | 7.92 b | | 2.933 a | 2.244 b | 2.111 b | |
LSD.005 | | | | | | | | |
IR | 1.001 | | | | 0.20 | | | |
TR | 1.0 | | | | 0.20 | | | |
IR XTR | 1.73 | | | | 0.36 | | | |
Table 4.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2021/2022.
Table 4.
Effect of the interaction between water irrigation levels and triacontanol (TR) foliar applications on growth parameters of strawberry plants in 2021/2022.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WHC | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Shoot Fresh Weight (g) | Shoot Dry Weight (g) |
---|
0 ppm TR | 36.67 c | 53.33 a | 23.33 e | 37.78 b | 9.333 d | 12.33 abc | 7.00 e | 9.556 c |
0.5 ppm TR | 47.00 b | 29.00 d | 34.67 c | 36.89 b | 12.73 ab | 8.333 de | 11.10 c | 10.72 b |
1 ppm TR | 55.00 a | 44.67 b | 46.67 b | 48.78 a | 13.57 a | 11.77 bc | 11.47 bc | 12.27 a |
Mean | 46.22 a | 42.33 b | 34.89 c | | 11.88 a | 10.81 b | 9.856 c | |
LSD.005 | | | | | | | | |
IR | 1.8 | | | | 0.8 | | | |
TR | 2.0 | | | | 1.0 | | | |
IR XTR | 3.2 | | | | 1.5 | | | |
Treatments | Root Fresh Weight (g) | Root Dry Weight (g) |
0 ppm TR | 7.667 de | 11.47 a | 5.667 f | 8.267 b | 1.713 e | 3.167 b | 0.92 f | 1.934 c |
0.5 ppm TR | 10.00 bc | 6.667 ef | 9.0 cd | 8.556 b | 3.067 b | 1.043 f | 2.057 d | 2.056 b |
1 ppm TR | 12.13 a | 9.467 bc | 10.80 ab | 10.80 a | 3.767 a | 2.567 c | 3.017 b | 3.117 a |
Mean | 9.933 a | 9.200 ab | 8.489 b | | 2.849 a | 2.259 b | 1.999 c | |
LSD.005 | | | | | | | | |
IR | 0.83 | | | | 0.1 | | | |
TR | 1.0 | | | | 0.1 | | | |
IR XTR | 1.4 | | | | 0.2 | | | |
Table 5.
Effect of water irrigation (IR) levels, triacontanol (TR) foliar applications, and their interactions on fruit quality parameters of strawberry plant in 2020/2021.
Table 5.
Effect of water irrigation (IR) levels, triacontanol (TR) foliar applications, and their interactions on fruit quality parameters of strawberry plant in 2020/2021.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WHC | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Total Soluble Acids % | Fruit Diameter (cm) |
---|
0 ppm TR | 4.4 d | 5.6 bc | 6.0 bc | 5.4 b | 2.4 c–e | 2.07 de | 1.5 e | 1.97 b |
0.5 ppm TR | 5.0 cd | 5.8 bc | 6.43 b | 5.7 b | 3.3 bc | 2.7 cd | 1.6 e | 2.5 b |
1 ppm TR | 5.67 bc | 6.80 b | 8.03 a | 6.8 a | 4.4 a | 3.9 ab | 3.1 bc | 3.8 a |
Mean | 5.033 c | 6.17 b | 6.82 a | | 3.4 a | 2.8 a | 2.06 b | |
LSD.005 | | | | | | | | |
IR | 0.7 | | | | 0.5 | | | |
TR | 0.7 | | | | 0.6 | | | |
IR XTR | 1.2 | | | | 0.9 | | | |
Treatments | Firmness (kg·m−2) | Fruit Length (cm) |
0 ppm TR | 0.09 e | 0.25 bc | 0.22 b–d | 0.19 b | 3.5 d–f | 3.3 ef | 2.7 f | 3.2 c |
0.5 ppm TR | 0.15 de | 0.19 b–d | 0.29 ab | 0.21 ab | 4.6 bc | 3.9 c–e | 2.9 f | 3.8 b |
1 ppm TR | 0.19 c–e | 0.22 b–d | 0.38 a | 0.26 a | 5.8 a | 5.2 ab | 4.4 b–d | 5.2 a |
Mean | 0.146 c | 0.22 b | 0.29 a | | 4.6 a | 4.2 a | 3.4 b | |
LSD.005 | | | | | | | | |
IR | 0.05 | | | | 0.58 | | | |
TR | 0.06 | | | | 0.6 | | | |
IR XTR | 0.09 | | | | 1.1 | | | |
Table 6.
Effect of water irrigation level and triacontanol (TR) foliar applications on fruit quality traits of strawberry plant during 2021/2022.
Table 6.
Effect of water irrigation level and triacontanol (TR) foliar applications on fruit quality traits of strawberry plant during 2021/2022.
Irrigation (IR) | 100% WHC | 80% WHC | 40% WH | Mean | 100% WHC | 80% WHC | 40% WHC | Mean |
---|
Treatments | Total Soluble Acids % | Fruit Diameter (cm) |
---|
0 ppm TR | 4.6 d | 5.3 cd | 5.3 cd | 5.04 c | 3.2 c–e | 3.0 de | 2.4 e | 2.8 c |
0.5 ppm TR | 5.03 d | 5.9 bc | 6.6 ab | 5.9 b | 4.3 ab | 4.0 b–d | 2.6 e | 3.5 b |
1 ppm TR | 5.3 d | 6.6 ab | 7.3 | 6.4 a | 4.9 a | 5.0 a | 4.1 a–c | 4.6 a |
Mean | 4.9 c | 5.9 b | 6.4 a | | 4.1 a | 3.8 a | 3.1 b | |
LSD.005 | | | | | | | | |
IR | 0.4 | | | | 0.5 | | | |
TR | 0.43 | | | | 0.6 | | | |
IR XTR | 0.74 | | | | 1.0 | | | |
Treatments | Firmness (kg·m−2) | Fruit Length (cm) |
0 ppm TR | 0.13 e | 0.2 cd | 0.23 a–d | 0.1878 b | 3.3 c–e | 2.9 de | 2.4 e | 3.0 b |
0.5 ppm TR | 0.18 de | 0.22 b–d | 0.24 a–c | 0.21 b | 4.2 bc | 3.6 cd | 2.50 e | 3.4 b |
1 ppm TR | 0.19 cd | 0.270 ab | 0.29 a | 0.25 a | 5.34 a | 4.8 ab | 4.0 bc | 4.7 a |
Mean | 0.17 b | 0.23 a | 0.25 a | | 4.28 a | 3.8 a | 2.9 b | |
LSD.005 | | | | | | | | |
IR | 0.03 | | | | 0.55 | | | |
TR | 0.03 | | | | 0.6 | | | |
IR XTR | 0.06 | | | | 0.9 | | | |