الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Two field experiments were carried out at the Experimental Station Farm, Faculty of Agriculture, Mansoura University, Egypt, during the two successive winter seasons of 2016/2017 and 2017/2018 to study the effect of irrigation water treatments and foliar spraying with some bio-activators as well as their interaction on growth, yield and its components and chemical composition of lettuce (balady cultivar).The two field experiments were carried out in a strip-plot design with four replications. The vertical-plots were allocated to two irrigation water treatments as following:1- untreated irrigation water (control treatment).2- Magnetically treated irrigation water.The horizontal-plots were included five foliar spraying treatments with some bio-activators as follows: 6- Without foliar spraying (control treatment). 7- Foliar spraying with yeast extract at rate of 100 ml/liter water. 8- Foliar spraying with chitosan at rate of 2.0 g/liter water. 9- Foliar spraying with liquid humic acid at rate of 1.0 ml/liter water. 10- Foliar spraying with algas at rate of 2.0 g/liter water. STUDIED charACTERS: A. Vegetative growth and yield: 1- Plant height. 2- Number of leaves/plant. 3- Fresh weight of leaves/plant. 4- Plant diameter. 5- Stem diameter. 6- Fresh weight of plant. 7- Dry weight of plant. 8- Total yield/fed. B. Photosynthetic pigments: 1- Chlorophyll a (mg/g FW). 2- Chlorophyll b (mg/g FW). 3- Total chlorophylls (mg/g FW). C. Chemical constituents of leaves: 1- Nitrogen percentage (N %). 2- Phosphorus content (P mg/100 g). 3- Potassium content (K mg/100 g).5- Sodium (Na mg/100 g). 6- Calcium (Ca mg/100 g). D- Quality characters: 1- Total soluble solids percentage (TSS %). 2- Total carbohydrates percentage (%). 3- Crude protein percentage (%). 4- Total sugars percentage (%). 5- Vitamin-C content ”Ascorbic acid” (mg/100 g FW). 6- Vitamin-E content (mg/100 g FW). 7- Nitrate ”NO3-N” (ppm). 8- Nitrite ”NO2-N” (ppm). ❑ The most important results obtained from this investigation can be summarized as follows: 1- EFFECT OF IRRIGATION WATER TREATMENTS: Obtained results show that irrigation water treatments (irrigation lettuce plants with normal water i.e. control treatment and magnetically treated water) had significant effects on vegetative growth and yield (number and weight of leaves/plant, fresh weight/plant and total yield/fed), photosynthetic pigments (chlorophyll a, b and total chlorophylls), chemical constituents of the leaves (nitrogen, phosphorus, potassium, sodium and calcium contents) and leaves quality characters (total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C, vitamin-E, nitrate and nitrite contents) in the two growing seasons. On the other hand, plant height, plant and stem diameter and dry weight/plant of lettuce in the two growing seasons as well as total carbohydrates percentages in the second season only were insignificantly affected by irrigation water treatments. from obtained results it could be observed that the maximum means of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents as well as the minimum values of sodium, calcium, nitrate and nitrite contents were recorded as a result of irrigation lettuce plants with magnetized water in both seasons. While, plants irrigated with untreated (normal) water recorded the lowest values of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents and the highest values of sodium, calcium, nitrate and nitrite contents in the two growing seasons. 2- EFFECT OF FOLIAR APPLICATION TREATMENTS: The obtained results show that studied foliar spraying treatments i.e. without foliar spraying (control treatment), foliar spraying with yeast extract (100 ml/liter water), chitosan (2.0 g/liter water), liquid humic acid (1.0 ml/liter water) and algas (2.0 g/liter water) significantly affected vegetative growth and yield (plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed), photosynthetic pigments (chlorophyll a, b and total chlorophylls), chemical constituents of the leaves (nitrogen, phosphorus, potassium, sodium and calcium contents) and leaves quality characters (total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C, vitamin-E, nitrate and nitrite contents) in both seasons. There were substantial differences in vegetative growth and yield, photosynthetic pigments, chemical constituents of the leaves and leaves quality characters of lettuce among all foliar spraying treatments and control treatment in both seasons. Foliar spraying lettuce plants with yeast extract at rate of 100 ml/liter water exceeded other foliar spraying treatments and produced the highest values of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents and the lowest values of sodium, calcium, nitrate and nitrite contents in both seasons of this study. Even as, foliar spraying lettuce plants with liquid humic acid at rate of 1.0 ml/liter water came in the second rank and followed by spraying with chitosan at rate of 2.0 g/liter water and then spraying with algas at rate of 2.0 g/liter water in both seasons. Whereas, the lowest values of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents and the highest values of sodium, calcium, nitrate and nitrite contents were resulted from control treatment (without foliar spraying) in both seasons.3. EFFECT OF INTERACTION: The obtained results indicate that there was significant effect due to the interaction between irrigation water and foliar application treatments on all studied characters of vegetative growth and yield (plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed), photosynthetic pigments (chlorophyll a, b and total chlorophylls), chemical constituents of the leaves (nitrogen, phosphorus, potassium, sodium and calcium contents) and leaves quality characters (total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C, vitamin-E, nitrate and nitrite contents) in both seasons. The highest values of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents and the lowest values of sodium, calcium, nitrate and nitrite contentsof lettuce were resulted from irrigation lettuce plants with magnetized water in addition spraying three times with yeast extract at rate of 100 ml/liter water in both seasons. Irrigation lettuce plants with magnetized water as well spraying with liquid humic acid at rate of 1.0 ml/liter water considered as the second best interaction treatment, followed by irrigation lettuce plants with untreated water with magnetic field and spraying three times with yeast extract at rate of 100 ml/liter water in both seasons. While, irrigation lettuce plants with normal water without spraying with any treatment resulted in the lowest values of plant height, number of leaves/plant, fresh weight of leaves/plant, plant diameter, stem diameter, fresh and dry weights of plant, total yield/fed, chlorophyll a, b and total chlorophylls, nitrogen, phosphorus, potassium, total soluble solids, total carbohydrates, crude protein and total sugars percentages, vitamin-C and vitamin-E contents and the highest values of sodium, calcium, nitrate and nitrite contents in both seasons. CONCLUSION from obtained results of this study, it can be concluded that irrigation lettuce plants with magnetized water in addition spraying three times after 20, 40 and 60 days from transplanting with yeast extract at rate of 100 ml/liter water or liquid humic acid at rate of 1.0 ml/liter water in order to obtain high growth, yield and its components, chemical composition and quality of lettuce balady cultivar under the environmental conditions of Mansoura district, Dakahlia Governorate, Egypt.