الفهرس 
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Abstract
The present investigation was conducted at the Experimental Farm of Faculty of Agriculture, Minia University, El Minia Governorate, Egypt during two successive seasons of 2020 and 2021.The main objectives of this study were to investigate the response of three soybean cultivars to irrigation intervals and planting methods. In both seasons, the experiment included 18 treatments which were the combinations of three irrigation intervals, two planting methods and three soybean cultivars. The experimental design was randomized complete blocks in split- split – plot arrangement with three replicates. The main plots occupied irrigation intervals (14, 21 and 28 days). The sub plots comprised the two planting methods (ridges and terraces). The sub - sub plots were devoted to soybean cultivars (Giza111, Giza22 and Crawford).
The obtained results could be summarized in the following topics :
I- Phenological traits:
1. Days to 50 % flowering:
Number of days to 50% flowering was highly significantly affected by irrigation intervals and planting methods in addition to the interaction among irrigation intervals, planting methods and soybean cultivars in both growing seasons. However, cultivars did not significantly differ for this trait in both seasons.
In general, the highest number of days to 50 % flowering was recorded for plants irrigated by interval of 14 days followed by those irrigated every 21 days with significant difference between them. However, the earliest plants were recorded for plots irrigated every 28 days in both growing seasons.
Concerning to the effect of planting methods i.e., ridges and terraces on number of days to 50% flowering in both seasons, it could be concluded that the latest plants were obtained for the planting on ridges in 2020 and 2021 seasons. On the other hand, the earliest plants were recorded for planting on terraces in both seasons.
The earliest cultivar in flowering was Giza-22 cultivar in first season and Giza 111 in the second season. Whereas the latest ones were Giza111 and Crawford in 2020 and 2021, respectively.
For the effect of interaction irrigation intervals x planting methods x cultivars interaction , it could be detected that the earliest plants in flowering were obtained for Giza 22 (29.87 day) and Crawford (27.42 day) sown on terraces and irrigated every 28 day in 2020 and 2021 seasons, respectively.
2- Number of days to 95% maturity
Number of days to 95% maturity was highly significantly affected by irrigation intervals and cultivars in both seasons in addition to planting methods in the second season, while this trait was not significantly affected by planting methods in the first season.
The first order interactions i.e., irrigation intervals x planting methods, as well as irrigations intervals x cultivars possessed highly significant effect on this trait in the second season. Whereas planting methods x cultivar interaction had significant effect on this trait in the second season. The second order interaction among the three studied factors had highly significant effect on days to 95% maturity in the second season.
Among studied irrigation intervals, the highest number of days to 95% maturity was recorded for plants irrigated by interval of 14 days followed by those irrigated every 21 days with significant difference between them. However, the earliest plants were recorded for plots irrigated every 28 days in both growing seasons.
Concerning to the effect of planting methods i.e., ridges and terraces on number of days to 95% maturity in both seasons, it could be concluded that the latest plants were obtained for the planting on ridges in 2020 and 2021 seasons. On the other hand, the earliest plants were recorded for planting on terraces in both seasons.
The earliest cultivar in maturity was Crawford in both seasons, whereas the latest one was G111 in both seasons of 2020 and 2021.
For the interaction effect between irrigation intervals and planting methods in the second season, the earliest plants in maturity were recorded for plots sown on terraces and irrigated by interval of 28 days, while the latest ones were recorded for plots planted on ridges and irrigated every 14 days.
Concerning the interaction between irrigation intervals and cultivars, it could be detected that the earliest plants in maturity were recorded for Giza111 irrigated by 28 days intervals. Concerning the interaction between planting methods and cultivars, it could be observed that the earliest plants in maturity were recorded for Giza 111 cultivar sown on terraces .
For the second order of interaction, irrigation intervals x planting methods x cultivars, the earliest plants in maturity were recorded for Giza 111 sown on the terraces and irrigated by interval of 28 days,
II- Growth parameters:
1. Dry matter/ plant at 45, 60 and 75 days in both seasons:
Irrigation intervals, planting methods and cultivars possessed significant effect on dry matter/plant at the three different ages of 45 ,60 and 75 days in both seasons except cultivars at 45 days age in 1st season. Concerning interactions, significant effect was detected on dry matter/plant for the following interactions (irrigation intervals x planting methods interaction at 45 and 60 days of 2nd season), (irrigation intervals x cultivars interaction at 45 of 2nd season and 75 days of 1st season), (planting methods x cultivars interaction at 60 and 75 days of 1st season) and (irrigation intervals x planting methods x cultivars interaction at 45 days in 2nd season and 60 and 75 days of 1st season).
The heaviest dry matter plant-1 was recorded for plants irrigated every 14 days followed by those irrigated every 21 days with significant difference between them at different ages in both seasons. However, the lightest dry matter per plant (g) was recorded for plots irrigated every 28 days at different sampling ages in both growing seasons.
Concerning to the effect of planting methods, the maximum values of dry matter plant-1 were recorded for the planting on ridges, while the contrast was recorded for planting on terraces at the three ages in 2020 and 2021 seasons. Giza 111 cultivar gave the heaviest dry matter plant-1 , whereas the lightest dry matter per plant was recorded for Crawford cultivar at different ages in both seasons of 2020 and 2021.
Concerning irrigation interval x planting methods interaction, it is worthy to note that the greatest dry matter plant-1 was achieved with irrigation by interval of 14 days and planting on ridges. About irrigation intervals x cultivars interaction and its effect on dry matter plant-1, it could be concluded that the maximum values of dry matter plant-1 were recorded for Giza111 at 60 days and Crowford at 75 days with irrigation every 14 days in 2021 and 2020 seasons, respectively.
With regard to planting methods X cultivars interaction and its effect on dry matter /plant at 60 and 75days ages in 2020 season and at 60 days in 2021 season, it could be concluded that the maximum values of dry matter /plant were recorded for Giza 111 plant on ridges at 60 days in both seasons and at ag of 75 days in 2020 season. For the second order of interaction, irrigation intervals x planting method x cultivar, it could be concluded that the maximum values of dry matter /plant were recorded for Giza 22 on planted on ridges and irrigated by 14 days interval at 45 and 60 days in 2021 and 2020. respectively, and Crowford irrigated every 14 days and planted on ridges at 75 days in 2020 season,
2. Leaf area /plant (cm2)
Irrigation intervals, planting methods and cultivars possessed significant effect on leaf area at the three ages of 45, 60 and 75 days in both growing seasons.
The interaction effect between irrigation intervals and planting methods had significant effect on this trait at 45 and 60 days ages in both seasons.
Irrigation intervals x cultivars interaction had highly significant at different ages of 45,60 and 75 days in the second season and significant effect on this trait at 45and 60 days ages in the first season.
Planting method x cultivars interaction possessed highly significant effect on this trait at 45 days age in the first season. The second order of interaction, irrigation intervals x planting methods x cultivars had significant effect on this trait at 45and 60 days in the first season, and had highly significant effect on this trait at 75 days in first season in addition to at 60 and 75 days ages in the second season.
The highest leaf area /plant (cm2) was recorded for plants irrigated by interval of 14 days followed by those irrigated every 21 days with significant difference between them at different ages in both seasons. Whereas exposing soybean plants to high water deficit via irrigation by interval of 28 days produced the lowest leaf area / plant at different sampling ages in both growing seasons .
For the effect of planting methods i.e., ridges and terraces on leaf area /plant (cm2) at different sampling ages of 45, 60 and 75 days in both growing seasons. The maximum values of leaf area /plant (cm2) were recorded for the planting on ridges, while the lowest ones were recorded for planting on terraces at different ages in both seasons.
In general, Giza111 gave the greatest values for leaf area per plant at different ages in 2020 and 2021 seasons, whereas the lowest leaf area per plant was recorded for Crawford cultivar at different ages.For the effect of interaction between irrigation intervals and planting methods at different ages in 2020 and 2021 seasons, the highest leaf area / plant was achieved via irrigation by interval of 14 days and planting on ridges. Regarding planting methods x cultivars interaction and its effect on leaf area /plant at 45 days age in 2020 season, it could be concluded that the highest leaf area /plant was recorded for Crowford planted on ridges. Concerning the second order of interaction, irrigation intervals x planting method x cultivar, it could be detected that the greatest leaf area /plant was recorded for Giza 111 planted on ridges and irrigated by interval of 14 days at different ages .
3.Leaf area index:
Irrigation intervals, planting methods and cultivars possessed highly significant effect on leaf area index (LAI) at the three ages of 45, 60 and 75 days in both growing seasons except cultivars at 45 days in the 1st season.
Irrigation interval x planting methods interaction was highly significant for LAI at the ages of 45 and 60 days in both seasons. Irrigation intervals x cultivars interaction had highly significant effect on LAI at 60 days age in the 1st season and at different ages of 45, 60 and 75 days in the 2nd season.
Planting method x cultivars interaction possessed highly significant effect on LAI at 45 and 60 days ages in the 1st season in addition to at 60 and 75 days in the 2nd season. The irrigation intervals x planting methods x cultivars interaction had significant effect on LAI at different ages in both seasons except at 45 days in the 2nd season.
The maximum values of leaf area index were recorded for plants irrigated by interval of 14 days followed by those irrigated every 21 days with significant difference between them at different ages in both seasons. However, the lowest values of leaf area index were recorded for plants irrigated by intervals of 28 days at different ages in both seasons.
Planting on ridges gave the highest values of LAI, however the lowest values were recorded for planting on terraces at different ages in both seasons.
Giza 22 gave the greatest values for LAI at 45 days age in 2020 and 2021 seasons in addition to 60 days age in the 2nd season. However, Giza 111 surpassed all studied cultivars at 60 days and 75 days in the 1st season and in both seasons, respectively. Whereas the lowest values of LAI were resulted for Crawford cultivar at different ages in both seasons.
For irrigation intervals x planting methods interaction , it is worthy to note that the highest LAI was achieved via irrigation by interval of 14 days and planting on ridges at 45 and 60 days in both seasons .With regard to irrigation intervals x cultivars interaction, the highest values for this trait were recorded for irrigation every 14 days with planting Giza 22 at 60 days age in both seasons, however, in the second season (2021), the highest LAI was recorded for Giza 22 and Giza 111 irrigated every 14 days at 45 and 75 days, respectively.
With regard to planting methods x cultivars interaction and its effect on leaf area index at 45 and 60 days ages in both seasons in addition to at 75 days in the second season, it could be detected that the highest values of leaf area index were recorded for Crowford and Giza 22 planted on ridges at 45 days in 2020 and 2021 seasons, respectively
For the effect of interaction ( irrigation interval x planting methods x cultivars) it could be detected that the highest values of leaf area index were recorded for Giza111 and Giza 22 planted on ridges and irrigated by intervals of 14 days at 60 days in first and second seasons, respectively, however the highest values for LAI at 75 days age in the two seasons were recorded for Giza 111 planted on ridges and irrigated every 14 days.
III Yield components:
1. Plant height (cm):
Irrigation intervals and planting methods in both seasons and cultivars in second season possessed significant effect on plant height. Irrigation intervals x cultivars interaction had significant effect on this trait in both seasons. The irrigation intervals x planting methods x cultivars interaction had significant effect on plant height in the 2nd season.
The tallest plants were recorded for plants irrigated by interval of 14 days in both seasons compared to plants irrigated every 21 and 28 days in both seasons.
Planting on ridges produced the tallest plants compared to those planting on terraces in both seasons.
Giza 22 cultivar gave tallest plants, whereas the shortest plants were recorded for Crowford in both seasons.
Concerning the interaction effect, tallest plants were recorded for Crowford and Giza 22 cultivars irrigated every 14 days in 2020 and 2021 seasons, respectively. For the effect of second order interaction, in the 2nd season, it is worthy to note that the tallest plants were recorded for Giza 22 planted on ridges and irrigated by interval of 14 days.
2. Number of branches/plants:
Number of branches/plants was highly significantly affected by irrigation interval, planting methods and cultivars in both seasons. Irrigation interval X planting methods interaction had significant and highly significant effect on this trait in first and second seasons, respectively.
With regard to the effect of irrigation regime, the maximum number of branches / plants was recorded for plants irrigated by intervals of 14 days followed by those irrigated every 21 days with significant difference between them. However, the lowest number of branches per plant was resulted for plants irrigated every 28 days in both growing seasons.
Concerning to the effect of planting methods i.e., ridges and terraces on number of branches per plant in both seasons, the highest number of branches per plant was obtained for the planting on ridges in both seasons. While, the lowest values were resulted for the planting on terraces in both seasons.
Giza 22 and Giza 111 cultivars gave the greatest number of branches per plant 1st and 2nd seasons, respectively.
Concerning, irrigation intervals X planting methods interaction effect on number of branches per plant. the maximum number of branches per plant was obtained for planting on ridges with irrigating by interval of 14 day in both seasons.
3. Number of pods per plant:
Irrigation intervals, planting methods and cultivars possessed significant effect on number of pods plant-1 in both seasons. Irrigation intervals x planting methods interaction had significant effect on this trait in the 2nd season. Irrigation intervals x cultivars interaction exhibit significant effect on this trait in both seasons. Irrigation intervals x planting methods x cultivars interaction exerted significant effect on number of pods plant-1 in the 2nd season.
The highest number of pods plant-1 was recorded for plants irrigated by interval of 14 days followed by those irrigated every 21 days with significant difference between them. However, the lowest number of pods per plant was resulted for plants irrigated every 28 days in both growing seasons.
Concerning to the planting methods, the highest number of pods per plant was obtained for the planting on ridges, whereas the lowest values for this trait were resulted from the planting on terraces in both seasons.
With regard to soybean cultivars, Giza111 and Giza 22 gave the greatest number of pods per plant in 2020 and 2021 seasons, respectively.
For the effect of irrigation interval X planting methods interaction on number of pods per plant in 2nd season. The maximum number of pods per plant was obtained for plots planted on ridges and irrigated by interval of 14 days.