الفهرس 
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Abstract
This study was carried out at private farm located in (31°14’10.7”N 31°34’02.5”E) El-Mohandes Village, Shirbin City, Dakahliea Governorate, Egypt, during the two consecutive seasons of 2017 and 2018. The purpose of the study is investigate the response of three levels of deficit irrigation water under both surface irrigation and drip irrigation system with soil amendments of humate and silicate potassium ore, on the growth, chemical constituents, fruit quality, and seed yield of sweet pepper (Capsicum annum L. ”California Wonder”) planted in clay soil. The experiment tested 30 treatments arranged in strip split plot design with three replicates. The horizontal plots were allocated to the irrigation systems (surface and drip irrigation), whereas the vertical-plots were devoted to the irrigation regimes at (40, 60 and 80% of irrigation water requirement (IWR)), while the sub plots were included five soil amendments treatments (without, 250, 500 kg.fed-1 potassium silicate ore, and 35 and 70 kg.fed-1 potassium humate).The obtained results could be summarized as follows:5.1. Vegetative growth parameters: Vegetative growth after 45 and 75 days from planting indicated a significant effect of both irrigation system (surface and drip). The maximum vegetative growth parameters were recorded under drip irrigation system. While the relative growth rate during the experiment found the opposite has been recorded. The highest significant values of vegetative growth parameters after both 45 and 75 days from transplanting were obtained with the highest level of irrigation regimes 80% from IWR followed by irrigation regimes at 60% from IWR, while the relative growth rate recorded the highest values with 40% from IWR. Soil application of potassium humate or silicate significantly affected in all vegetative growth parameters after 45 and 75 days. The highest mean values recorded with 75 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate comparing without soil amendments during both seasons. All vegetative growth parameters after 45 and 75 days scored the highest mean values under drip irrigation system at 80% of IWR.The highest mean values of vegetative growth scored with addition of 75 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate under drip irrigation system after 45 and 75 days during both seasons.A stimulation significant effect in all plant growth parameters after 45 and 75 days as result of soil amendments in form of potassium humate, since it recorded the highest significant values for aforementioned traits when using 70 kg.fed-1 at 80% of IWR.The effect of interaction among all studied factors on vegetative growth parameters after both 45 and 75 days from transplanting. The results showed that the soil amendments with potassium humate at the rate of 70 kg.fed-1 followed by potassium silicate at 500 kg.fed-1 under irrigation regime at 80% from IWR under drip irrigation were recorded the highest mean values of vegetative growth parameters.5.2. Chemical Constituents of Leaves:Both of the irrigation system significantly on chemical constituents of leaves (N, P, K, Si % and chlorophyll content) values. Drip irrigation was the most effective on chlorophyll content, N, P, K and Si% comparing with the surface one and the same trend was true during both seasons.The highest mean values of chemical constituents of leaves were recorded with the highest level of irrigation 80% from IWR following 60% IWR, while the lowest one recorded with 40% during both seasons.The highest mean values of N, P & K % and total chlorophyll were recorded with soil addition with 70 kg.fed-1 potassium humate while the highest value of Si% recorded with 500 kg.fed-1 potassium silicate comparing the control during 2017 and 2018.The drip irrigation was the highest values of N, P & K % and total chlorophyll followed by surface irrigation at 80% from IWR during both seasons.The highest mean values of N, P, K% and total chlorophyll were recorded with drip irrigation system and 70 kg.fed-1 followed by 500 kg.fed-1 potassium silicate.The highest mean values for chlorophyll content, N, P and K% in leaves were found to be associated with the soil addition of 70 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate, while highest value of Si was associated with addition of 500 kg.fed-1 potassium silicate under irrigation regime at 80% from IWR.Regarding to the effect of triple interaction among irrigation system, irrigation regimes and soil amendments, the highest mean values of chlorophyll content, N, P and K% in leaves were resulted from drip irrigation system at 80% of IWR with soil amendments of 70 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate. While increase in Si concentration up to the highest value recorded with the same treatments but with the addition of 500 kg.fed-1 potassium silicate under drip irrigation system. The same trend was true during both seasons 5.3. Flowering and Fruit Yield Parameters:The maximum and significant of flowering and fruit yield parameters were observed with drip irrigation system, which due to the higher No. of flowers/ plant, fruit setting% as well as early and total yield.With increasing irrigation regimes the flowering and fruit yield parameters were increased, the highest mean values of flowering and fruit yield parameters were scored with the highest irrigation regimes at 80% followed by 60% of IWR during both seasons.The highest mean values No. of flowers, number of fruits/ plant for early and total yield as well as early and total yield were obtained from soil amendments with 70 kg.fed-1 of potassium humate followed by 500 kg.fed-1 potassium silicate.The highest values flowering, early and total yield of sweet pepper were recorded when plants irrigated at 80% from IWR under drip irrigation system. While the lowest were recorded with 40% from IWR under surface irrigation during the two seasons of study.The drip irrigation system with soil addition at 70 kg.fed-1 potassium humate followed by addition with 500 kg.fed-1 potassium silicate were recorded the highest values of flowering and fruit yield parameters.The highest mean values flowering and fruit yield parameters were scored with addition 70 kg.fed-1 potassium humate followed by addition 500 kg.fed-1 potassium silicate with irrigation at 80 % of IWR during two seasons.With regard to the interaction treatments among irrigation system, irrigation regime and soil amendments of potassium humate or silicate at different rates, the irrigation of sweet pepper plants at 80% of IWR under drip irrigation with the soil addition at 70 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate significantly increased early and total yield and scored the highest mean values comparing with plants irrigated with 40% of IWR under surface irrigation in both seasons.5.4. Fruit quality parameters Drip irrigation system recorded the highest mean values of all fruit quality (dry matter %, total chlorophyll, carotene, total sugars, carbohydrates and Vitamin C) comparing to the values recorded with surface one.Increasing irrigation regimes increased fruit quality and the highest mean values scored with the highest level of irrigation 80% followed by 60% IWR during first and second season.The rate of 70 kg.fed-1 of potassium humate as soil amendments were increased all aforementioned parameters followed by 500 kg.fed-1 of potassium silicate comparing with the other treatments.The highest mean values of chemical fruit quality recorded with drip irrigation at 80% from IWR.The highest mean values of dry matter %, total chlorophyll, carotene, TSS%, total sugar, carbohydrates and vitamin C were achieved with the addition of 70 kg.fed-1 followed by 500 kg.fed-1 potassium silicate under 80% from IWR compared to the untreated plants under the same soil addition.The highest mean values of dry matter %, total chlorophyll, carotene, TSS%, total sugar, carbohydrates and vitamin C indicated with the irrigation at 80% from IWR and 70 kg.fed-1 potassium humat followed by 500 kg.fed-1 potassium silicate.The interaction among irrigation system, irrigation regimes and soil amendments of potassium humate or silicate at different rates had a significant effect on fruit quality of sweet pepper. That irrigation at 80% of IWR under drip irrigation resulted in the highest mean values of dry matter, total chlorophyll, carotene, total sugar, carbohydrates and vitamin C especially with the soil application of 70 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate under drip irrigation. While the lowest values recorded with irrigation at 40% of IWR with the surface irrigation and without soil addition.5.5. Seed yield parameters:The good promising result time to germination, germination %, No. of seeds/fruit, weight of seeds/fruit, weight of seeds/plant, weight of 1000 seed, and yield of seed/fed were recorded with the drip irrigation system comparing with the surface one, while mean time to germination had no significant effect. Increasing irrigation regimes lead to an increase in seed characterize. The highest mean values recorded with the highest irrigation regimes at 80% followed by 60% of IWR while the lowest values recorded with the lowest level 40% from IWR, except mean time to germination.Application of 70 kg.fed-1 potassium humate followed by addition potassium silicate at 500 kg.fed-1were recorded the highest mean value of seed parameters comparing with the control treatments. The same treatments recorded the lowest mean value of mean time to germination.The highest values of the aforementioned parameters were recorded by plants irrigated at 80% followed by 60% IWR under drip irrigation except mean time to germination scored the highest values under surface irrigation system at 40% from IWR.Drip irrigation recorded the highest mean values of seed parameters over the surface system with soil amendments at 70 kg.fed-1 potassium humate followed by 500 kg.fed-1 potassium silicate except mean time to germination scored the highest values under surface irrigation system without soil addition.The highest values of seed parameters of sweet pepper plant were recorded when plants irrigated at 80% from IWR with addition potassium humate at 70 kg.fed-1 followed by 500 kg.fed-1 potassium silicate.With regard to the interaction treatments among irrigation system, irrigation regime and soil amendments of potassium humate or silicate at different rates, the sweet pepper irrigated at 80% of IWR under drip irrigation and soil application at the rate 70 kg.fed-1 potassium humate or potassium silicate at 500 kg.fed-1 were produced fruits with maximum No. of seeds/fruit, weight of seeds/fruit, weight of seeds/plant, yield of seed/fed, weight of 1000 seed, and germination%.from previous findings, it can be concluded that the drip irrigation system produced the best significantly values of vegetative growth characteristics, chemical constituents, early yield and total fruit yield as well as total seed yield compared to the surface irrigation system. Results indicated that significantly highest values of all parameters were recorded from the irrigation regime at 80% followed with irrigation at 60 % of the irrigation water requirement (IWR). Results also showed that the higher values of all parameters were obtained from soil amendments at 70 kg/fed. from potassium humate followed with 500 kg/fed. from potassium silicate ore.In addition, the results showed that a higher average for all the above parameters were obtained from soil amendments at 70 kg/fed from potassium humate followed with 500 kg/fed. from potassium silicate ore under drip irrigation system at 80% (6922 m3/fed.) followed with irrigation at 60% of IWR (5192 m3/fed.).Finally, we recommend this treatment because it saves water irrigation (4091and 5821 m3/fed. respectively) and obtains the best vegetative growth, chemical constituents traits and yield with improved seeds quality in sweet pepper plants grown under the same conditions in Dakahlia Governorate.