الفهرس 
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Abstract
In order to investigate the impact of tillage system, plant population densities and weed control treatments as well as their interactions on growth, weed characteristics, yield and its attributes of soybean (Glycine max, L., Merrill) cv. Giza111, two field experiments were took place at the experimental farm of the Faculty of Agriculture, Minia University, during two successive seasons of 2019 and 2020. Wheat was sown, on ridges in both seasons as the previous crop.
The obtained results could be summarized as follow:
1. Effect of tillage system on:
1.1. Vegetative growth parameters:
All vegetative growth parameters of soybean i.e., plant height, number of branches, leaf area and leaf area index were increased due to use full-till comparing with no-till system in both seasons. In most cases, the highest values of the abovementioned aspects were achieved for full-tilled plots.
1.2. Weed characters:
All dry weights of weeds (narrow, broad and total weeds) in soybean field were reduced due to full-till relatively to no-till in both seasons. In all cases, the lowest values of the previous traits were obtained with full-tilled plots.
1.3. Yield components:
All yield components traits of soybean (number of pods per plant, 100-seeds weight and seed yield/plant) were improved due to adapting full-till comparing to no-till in both seasons. In all cases, the highest values of the previous traits were recorded with full-tilled plots.
1.4. Yield parameters:
Full-till increased both of seeds and straw yields comparing with no-till in both seasons. In all cases, the highest values of yields were produced with full-tilled plots.
2. Effect of plant population density on:
2.1. Vegetative growth parameters:
Sowing plants at a density of 140000 plants/fed. produced the highest values of branches number per plant, leaf area, and leaf area index, while the tallest plants were achieved at 210000 plants/fed. in both seasons.
2.2. Weed characters:
Increasing plant population density from 140000 to 210000 plants/fed. reduced weeds dry weights (narrow, broad and total weeds) in both seasons. The lightest weeds dry weights were produced at 210000 plants/fed., however, the heaviest weeds dry weights were produced at 140000 plants/fed. in both seasons.
2.3. Yield components:
Plant population at a density of 140000 plants/fed. gained the highest values of pods number per plant and 100 seed weight, while the heaviest seed yield/plant was recorded with 186666 plants/fed. in both seasons.
2.4. Yield parameters:
The heaviest seed and straw yields per feddan were achieved for plant population of 186666 plants/fed., while, the lightest values were recorded for plots sown at a rate of 210000 plants/fed. in both seasons.
3. Effect of weed control methods on:
3.1. Vegetative growth parameters:
In most cases, hand hoeing twice (35 and 50 DAS) produced the tallest plants with highest number of branches, while plants received select super 500 ml/fed. (35 DAS) plus Basagran 750 ml/fed. (50 DAS) recorded the largest LA and LAI.
3.2. Weed characters:
In most cases, the heaviest dry weights of weeds (narrow, broad and total) were produced for plots received select super (500 ml/fed.) at 35 DAS + Basagran (750 ml/fed.) at 50 DAS. While, the lightest values were recorded for plots received select super (250 ml/fed.) + Basagran (750 ml/fed.) at 35 DAS in both seasons.
3.3. Yield components:
The highest number of pods/plant, 100-seeds weight and seed yield/plant were recorded for the treatment of select super (500 ml/fed.) at 35 DAS + Basagran (750 ml/fed.) at 50 DAS, while the lowest ones were resulted in plots received hand hoeing twice (35 and 50 DAS) or select super (250 ml/fed.) at 35 DAS + Basagran (750 ml/fed.) at 50 DAS.
3.4. Yield parameters:
Treating plants with select super 250 ml/fed. (35 DAS) plus Basagran 750 ml/fed. (50 DAS) produced the heaviest yields either of seeds or straw, while, hand hoeing twice (35 and 50 DAS) recorded the lightest values in both seasons.
4. Effect of interactions on:
4.1. Vegetative growth parameters:
- The interaction between tillage system and plant densities interaction had highly significant effect on plant height. The tallest plants were recorded for full-till with 210000 plants/fed. and the shortest ones were resulted in no-till with 140000 plants/fed.
- Tillage system X weed control treatments interactions possessed significant effect on plant height. The tallest plants were recorded for plots received full-till with hand hoeing twice at 35 and 50 DAS, while the shortest ones recorded for no-tilled plots received select super 250 ml/fed. + Basagran 750 ml (35 DAS).
- Plant density X weed control treatments interaction possessed highly significant effect on plant height. In most cases, the tallest plants were recorded for sowing 210000 plants/fed. with adding select super 500 ml/fed. (35 DAS) + Basagran 750 ml/fed. (50 DAS), however, the shortest plants were obtained on plots sown with 140000 plants/fed. and received select super 250 ml/fed. + Basagran 750 ml/fed. (35 DAS).
- The interaction among the three studied factors had highly significant effect on plant height. Generally, plots sown at 210000 plants/fed. and received select super 500 ml/fed. (35 DAS) + Basagran 750 ml/fed. (50 DAS) either with till or no-till system gave the tallest plants, while the shortest plants were resulted in full-till plots sown at 140000 plants/fed. and received select super 500 ml/fed. + Basagran 750 ml/fed. (35 DAS). Other types of interactions did not exhibit significant effect on this in both seasons.
- The effect of interactions among tested factors on number of branches/plant did not show any significant effect on this trait.
- It could be concluded that tillage system X plant densities interaction had significant effect on leaf area/plant and leaf area index. It could be observed that the highest leaf area/plant and leaf area index was achieved for the treatment of full-till with 140000 plant/fed. All other types of interactions among examined factors did not show any significant effect on these traits.
4.2. Weed characters:
- It could be concluded that tillage system X plant densities interaction had significant effect on dry weight of narrow and broad leaves weed as well as total weeds. The heaviest dry weights of narrow and broad leaves weed as well as total weeds were recorded for no-till with 140000 plants/fed., while the lightest ones were resulted for full-till with 210000 plants/fed. On the other hand, all other types of interactions among the tested factors on dry weights of narrow leaves weed did not observe any significant effect in this concern.
- The interaction between plant densities and weed control showed significant effect on dry weight of total weeds. The heaviest dry weights of total weeds were recorded for plots of 140000 plants/fed. and treated with select super (500 ml/fed.) at 35 DAS + Basagran (750 ml/fed.) at 50 DAS. However, the lowest ones were produced for plots of 210000 plants/fed. and treated with select super (500 ml/fed.) + Basagran (750 ml/fed.) at 35 DAS or treated with select super (250 ml/fed.) at 35 DAS + Basagran (750) ml/fed. 50 DAS.
- All other types of interactions among examined factors on dry weight of total weeds did not show any significant effect.
4.3. Yield components:
- Tillage system X plant densities interaction possessed highly significant effect on number of pods/plant. The highest values were recorded with full-till with 140000 plants/fed., while, the shortest ones were resulted from no-till with 210000 plants/fed.
- It is interesting to observe that plots sown at 140000 plants/fed. and received select super (500 ml/fed.) at 35 DAS + Basagran (750 ml/fed.) at 50 DAS under full-till system gave the highest values of pods number/plant, while the lowest ones were recorded for no-till plots sown at 210000 plants/fed. and received hand hoeing twice at 35 and 50 days. All other types of interactions did not exhibit significant effect on this trait.
- Tillage system X plant densities interaction had not exhibit significant effect on 100-seed weight.
- Tillage system X weed control treatments interaction possessed highly significant effect on 100-seed weight. The heaviest weights were recorded for plots received full-till with select super 250 ml/fed. (35 DAS) + Basagran 750 ml (50 DAS). The lightest ones were recorded for no-tilled plots received select super 250 ml/fed. + Basagran 750 ml (35 DAS) or received hand hoeing twice (35 and 50).
- The interaction effect between plant density X weed control treatments possessed highly significant effect on 100-seed weight. The treatment of sowing 140000 plants/fed. plus spraying with select super 250 or 500 ml/fed. (35 DAS) + Basagran 750 ml/fed. (50 DAS) recorded the heaviest weight. While the lowest ones were obtained on plots sown at 210000 plants/fed. and received select super 250 ml/fed. (35 DAS) + Basagran 750 ml/fed. (50 DAS).
- The interaction among the three examined factors had highly significant effect on 100-seed weight. Plots sown at 140000 plants/fed. and received select super 500 ml/fed. + Basagran 750 ml/fed. (35 DAS) under full-till system gave the highest values, while the lowest ones were given with no-till plots sown at 210000 plants/fed. and received hand hoeing twice (35 and 50 DAS).
- Tillage system X plant densities interaction possessed significant effect on seed yield/plant. The highest values were recorded for plots sown at 186666 plant/fed. under full-till. On the other hand, the plots sown at 210000 plant/fed. under no-till produced the lowest values.
- The interaction among the three tested factors had highly significant effect on seed yield/plant. Plots sown at 140000 plants/fed. and received select super 250 ml/fed. (35 DAS) + Basagran 750 ml/fed. (50 DAS) under full-till system gave the highest values, while the lowest ones were given with no-till plots sown at 210000 plants/fed. and received select super 250 ml/fed. + Basagran 750 ml/fed. (35 DAS).