الفهرس 
Effect of water stressOnly 14 pages are availabe for public view
 |  | from | 205 |  |  |
| | | from | 205 | | |
Abstract
In this study, two field experiments were carried out during the two growing seasons of 2013/2014 and 2014/2015, at the experimental farm, Faculty of Agriculture, Ain Shams University, Shoubra El-Kheima, Egypt, in order to investigate the effect of irrigation after the depletion of different available soil water levels, soil conditioner, foliar application of glycine betaine and Potassium silicate on vegetative growth, bulbs yield and its components as well as chemical composition of garlic bulb (Allium sativum L.), cv. Sids-40 under water stress conditions.
Irrigation at different percentages of available soil water depletion (55-60%, 70-75% and 85-90%) Irrigation treatments were started six weeks after planting. Soil conditioner was applied to the soil while preparation, commercial (Hundz) at the rates of 2 m3/Fed and control (the control was without conditioner). It was applied to the field surface before planting. foliar applications of glycine betaine were used at 2 mM/L and potassium silicate was used at 0.5 g /L and sprayed after 50, 65, 80, 95, 110, 125 and 140 days, from planting compared with control (sprayed with distilled water) The area of the experimental plot was14 m2, consisted of five rows; each row was 4 m length and 0.7 m width. Garlic cloves were planted at a distance of 7 cm apart on both sides of ridges, an alley (1 m wide) was left as border between irrigation treatments.
The results of this experiment can be summarized as follows:
Vegetative growth characters
1- Effect of irrigation levels:
Vegetative growth responded positively to irrigation at different percentages of available soil water depletion. Irrigation at depletion of 55-60 % available soil water increased plant length, bulb, leaf fresh weight, leaf dry weight, leaf area and chlorophyll reading in the two seasons as compared with the other studied irrigation treatments, but Bulb dry weight was significantly increased as a result of Irrigation at depletion of 55-60 % available soil water in the first tested season and not significant in the second tested season. In addition, the differences detected for irrigation levels was not significant in leaf number and Bulb diameter.
2- Effect of soil conditioner:
Applying soil conditioners were significant in plant length, bulb, leaves fresh weight, leaf area and chlorophyll reading in the two seasons in the two tested seasons. Bulb dry weight was significantly increased as a result of applying soil conditioners in the first tested season and not significant in the second tested season. leaves dry weight was decreased as a result of applying soil conditioners in the first tested season and not significant in the second tested season. In addition, applying soil conditioner was not significant in leaf number and bulb diameter.
3- Effect of foliar spray substances
The foliar application of glycine betaine was significant in bulb fresh weight after 150 days from planting, leaves fresh weight after 120 days from planting and chlorophyll reading in the two seasons. Bulb dry weight after 150 days from planting responded positively to the foliar application of glycine betaine in the second tested season and responded positively to potassium silicate in first tested season.
In addition, the foliar application of glycine betaine was significant in leaf area after 120 days from planting in the first tested season and not significant in the second tested season, but leaf area after 150 days from planting the differences detected for the foliar application of glycine betaine was not significant in first seasons and significant in the second tested season.
Application of glycine betaine or potassium silicate led to a significant increase in plant length after 120 days from planting without significant affect in first season, but in the second season glycine betaine resulted the highest values. Application of glycine betaine or potassium silicate led to a significant increase in vegetative growth without significant affect expressed as plant length, bulb fresh weight after 120 days from planting, leaves fresh and dry weight after 150 days from planting. In addition, application of glycine betaine or potassium silicate was not significant in bulb diameter.
4- Interaction effect among irrigation levels, soil conditioners and foliar application of glycine betaine or Potassium silicate.
The interaction among irrigation at depletion of different percentages of available soil water applying conditioners soil of Hundz soil and foliar application of glycine betaine or potassium silicate had generally, a significant effect on vegetative growth. Moreover, the highest values of plant length, bulb fresh weight, leaf fresh weight of garlic after 120 days from planting, leaf area, bulb diameter and chlorophyll were produced with irrigation at depletion of 55-60% available soil water with applying soil conditioners and foliar application of glycine betaine or potassium silicate in the two seasons. At the same time leaf fresh and dry weight of garlic after 150 days from planting responded positively to irrigation at depletion of 55-60% available soil water without applying soil conditioners and foliar application of glycine betaine, while bulb dry weight gave the highest values by irrigation at depletion of 55-60% available soil water with applying soil conditioners as for foliar application of glycine betaine or potassium silicate not significant in the first tested season, in the second season irrigation at depletion of 70-75% available soil water without applying soil conditioners and foliar application of glycine betaine increased bulb dry weight. In addition, the differences detected for irrigation levels was not significant in leaf number.
Yield and its components
1- Effect of irrigation levels:
Irrigation at depletion of 55-60% available soil water resulted in the highest values of yield, bulb fresh weight, bulb and neck diameter, bulbing ratio, cloves fresh and dry weight per bulb, total cloves number, average clove weight and as compared with the other studied irrigation treatments in the two seasons.
2- Effect of soil conditioner:
Applying soil conditioner were significant in yield, cloves fresh and dry weight per bulb, bulb fresh weight, bulb and neck diameter and total cloves number while cloves dry matter percent was reduced, soil conditioner was insignificant in bulbing ratio.
3- Effect of foliar spray substances
Application of glycine betaine or potassium silicate were insignificant in bulb diameter and bulbing ratio, foliar application of distilled water gave the highest values of cloves dry matter percent. The foliar application of glycine betaine increased yield, cloves fresh and dry weight per bulb, bulb fresh weight, bulb and neck diameter, average clove weight.
The foliar application of potassium silicate gave the highest values of total cloves number in the second seasons but was insignificant in the first season.
4- Interaction effect among irrigation levels, soil conditioners and foliar application of glycine betaine or potassium silicate.
The interaction between irrigation at different percentages of available soil water depletion with applying soil conditioners and foliar application of glycine betaine or potassium silicate, plants irrigated after depletion of 55-60% available soil water with applying soil conditioners and foliar application of glycine betaine had the highest cloves and bulb fresh weight, neck diameters and yield.
Irrigation after depletion of 55-60% available soil water with applying soil conditioners and foliar application of glycine betaine or potassium silicate significantly increased cloves number and bulb diameter. Irrigation after depletion of 85-90% available soil water without applying soil conditioners and foliar application of distilled water increased cloves dry matter percent.
Average clove weight responded positively to irrigation after depletion of 55-60% available soil water with applying soil conditioners and foliar application of glycine betaine in the first season, but in the second season irrigation after depletion of 55-60% available soil water without applying soil conditioners and foliar application of glycine betaine gave the highest value.
The differences detected in bulbing ratio were insignificant, while in cloves dry weight was recorded by irrigation after depletion of 55-60% available soil water with or without applying soil conditioners and foliar application of glycine betaine in two season.
Chemical analyses
1- Effect of irrigation levels:
Chemical analyses of garlic responded positively to irrigation at different percentages of available soil water depletion. Irrigation at depletion of 55-60% available soil water resulted in the highest values of nitrogen, protein content and total carbohydrates percentage as compared with the other studied irrigation treatments in the two seasons whereas resulted in the lowest values of free proline, phenols, catalase, total sugars, ascorbic acid, total soluble solids. However, irrigation at depletion of 70-75% available soil water gave the highest values of phosphorus in the two seasons and total free amino acids in the second season without significant affect in the first season as compared with the other studied irrigation treatments.
2- Effect of soil conditioner:
Applying soil conditioner were significant in total carbohydrates and protein content. Ascorbic acid and nitrogen were significant in the second season and insignificant in the first season. Applying soil conditioner reduce free proline, catalase, total sugars, phosphorus and were insignificant in total free amino acids and phenols. Total soluble solids increased in first season and reduced in second season.
3- Effect of foliar spray substances
Application of glycine betaine or potassium silicate were insignificant in total free amino acids and phenols, while foliar application of glycine betaine increased ascorbic acid, nitrogen and protein content. Foliar application of potassium silicate gave the highest values of total soluble solids and total sugars, foliar application of distilled water gave the highest values of free proline and catalase in the two tested seasons.
Application of potassium silicate gave the highest values of phosphorus in the first seasons, application of glycine betaine gave the highest values of phosphorus in the second seasons.
Application of glycine betaine or potassium silicate were insignificant in total carbohydrates in the first season but in the second season foliar application of potassium silicate gave the highest values.
4- Interaction effect among irrigation levels, soil conditioners and foliar application of glycine betaine or Potassium silicate.
the effect of irrigation at different percentages of available soil water depletion, applying soil conditioners and foliar application of glycine betaine or potassium silicate on catalase activity, total sugar and proline content responded positively to irrigation at depletion of 85-90% available soil water without applying soil conditioners and foliar application of distilled water in the two tested seasons.
Ascorbic acid and total soluble sugars were produced with irrigation at depletion of 85-90 % available soil water without applying soil conditioners and foliar application of glycine betaine were the highest value.
Irrigation at depletion of 55-60% available soil water with applying soil conditioners and foliar application of glycine betaine or potassium silicate significantly increased total nitrogen content, protein content and total carbohydrates in the two seasons. The highest values of phosphorus content were produced by Irrigation at depletion of 70-75% available soil water without applying soil conditioners and foliar application of distilled water, while total soluble phenols responded positively to Irrigation at depletion of 70-75% available soil water without applying soil conditioners and foliar application of glycine betaine or Potassium silicate in the two seasons.
Total free amino acids were increased by Irrigation at depletion of 70-75% available soil water with applying soil conditioners and foliar application of distilled water in the first season, but in the second season irrigation at depletion of 70-75% available soil water without applying soil conditioners and foliar application of glycine betaine gave a highest value.
Conclusions:
It was concluded that the different levels of irrigation affect vegetative growth and the productivity and quality of garlic, the irrigation after depletion of 55-60 % available soil water and the addition of soil conditioner at a rate of 2m3 and foliar application of 2 mM/L glycine betaine and 0.5 mM/L potassium silicate.