الفهرس 
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Abstract
The greenhouse microclimate may be affected by orientation of the greenhouse, latitude area of the greenhouse, canopy area inside the greenhouse, bare soil surface area inside the greenhouse, structural design (shape and size) of the greenhouse, properties of the material used for construction of the greenhouse, etc. The efficiency of the plant production in greenhouse depends significantly the adjustment of the optimal climate growth conditions to achieve high yield at low expense, good quality and low environmental load.
The Principle optimal greenhouse environmental control approaches can be distinguished: (1) focus on maximal output, such as crop yield and quality, (2) focus on maximum product yield per average unit of resource input, (3), focus on minimal resource input per unit product and (4) focus on expected economic return. By using optimal control quantitative scientific knowledge of the greenhouse and crop is used determine the optimal control inputs.
The experiments were carried out during the agricultural season of 2002/2003, in three different greenhouse forms, N-S oriented, located at Ismalia City (latitude 32.26 °N, longitude 30.33 °E, and altitude 10 m above the sea level) on the coastal area of eastern Egypt.
The main aim of this work is to improve the sweet pepper production by controlling and management of the environmental factors affecting the pepper production. This can be achieved by choosing three of the most popular plant-house systems in the world. These houses are: fully controlled greenhouse (G1), flat-roof net-house (G2) and modified Quonset (G3). The summary and conclusion can be divided into four parts as following:
(1) Environmental parameters.
(2) Sweet pepper parameters.
(3) Irrigation performance indicators.
(4) Techno-economical analysis.
First: Environmental parameters
1- Temperature:
The temperature record during the whole growth period in fully controlled (G1), flat-roof net-house (G2) and modified Quonset (G3) ranged from 17.1 to 29.3, 7.0 to 34.9 and 6.6 to 40.9°C respectively, while the optimum temperature of pepper growth ranged from 18 to 24°C. The outside temperature ranged from 7.0 to 32.6 ْC. The average difference between daytime and nighttime (∆T) in G1 ranged from 4.2 to 6.5 ْC, while it ranged from 1.8 to 7.5 ْC for G2 and from 4.6 to 8.1 ْC for G3. On the other hand, the average daily temperature ranged from 19.8 – 22.6, 12.8 – 28.1 and 11.4 – 3 5.5 ْC for G1, G2 and G3, respectively.
2- Relative Humidity (RH):
The outside RH ranged from 32 – 91%, during the whole growth period, RH ranged from 64 – 94 % inside the full controlled greenhouse (G1). On the other hand RH ranged from 39 – 99 and 37 – 100% inside both G2 and G3, respectively. The optimum RH should be in the range of 40 to 70%. It was concluded also, that the RH difference (Δ RH) between the daytime and night time ranged from 2-16%, 2-28% and 13-31% for G1, G2 and G3, respectively. On the other hand, the outside difference of RH ranged from 17 – 34%.
3- Vapor pressure deficit (VPD):
VPD ranged from 0.11- 3.36, 0.12-1.25, 0.01 – 2.8, and 0.01- 4.55 kPa for outside, fully controlled (G1), flat-roof net-house (G2) and modified Quonset (G3), respectively. The average daily VPD ranged from 0.42-1.46, 0.29-0.50, 0.18-1.18 and 0.18-1.83 kPa for the same previous order. The optimum VPD should be between 0.2 -2.5 kPa for sweet pepper. The VPD differences ( VPD) between the daytime and nighttime ranged from 0.43-1.46, 0.13-0.60, 0.06-1.15 and 0.27- 1.62 kPa for outside, G1, G2 and G3, respectively.
4- Solar radiation:
The average solar radiation ranged from 254-434, 193-291, 203-386 and 223- 386 W/m2 for outside, G1, G2 and G3 respectively, while the maximum solar radiation recorded values were 778, 478, 578, and 685 W/m2 for the same previous order.
Second: Sweet pepper parameters:
1- The vegetative parameters:
Plant height, number of nods, internodes length, number of leaves, leaves area, stem diameter and leaf area index were taken as the most important indicators of vegetative parameter of sweet pepper grown in different plant-houses, fully controlled (G1), flat-roof net-house (G2) and modified Quonset (G3). It is concluded that the total plant height reached 315.5, 186.4, and 206.1 cm during the whole growth period of sweet pepper plants grown under the fully controlled (G1), G2 and G3, respectively. The leaf area index reached 6.16, 2.23, and 2.44 for the same pervious order.
2- The flowering and setting parameters:
The results showed that the length of suitable period of flowering and setting of the fully controlled (G1) was 299 days while it was only 70 days for both (G2) and (G3) systems. The average number of flowers per plant for the fully controlled system (G1) was higher than that of the number of both (G2) and (G3) systems where it was 78 flower /plant for fully controlled type (G1) and was 60 and 56 flower/ plant for both (G2 and G3) systems, respectively.
The fruit setting rate, for G1 was 2 times of those of G2 and G3 systems. The fruit setting rate of fully controlled (G1) was 44.03 while they were 22.61 and 21.6% for both (G2 and G3) systems, respectively.
3- Yield and yield components:
The total yields of sweet pepper were 22.9, 8.27 and 6.97 kg/m2 for G1, G2 and G3, respectively. The percentage of the exportable yield were 85.66, 67.33 and 55.95 % from grade1 for the same pervious order. Number of fruit/m2 and per plant of G1 (114.5) was higher significantly than those of G2 (45.2) and G3 (40.3). The same trend was occurred in the number of fruit/plant. Meanwhile, the average fruit weight of G1 significantly from both G2 and G3. The different between G1, G2 and G3 in total yield was significant where, G1 reached the highest value (6870 g/plant) while G3 recorded the lowest value (2093.3 g/plant), which represents 30.5 % of the G1 total yield. TSS in G1 fruits (9.395%) was higher that those of both G2 (8.67 %) and G3 (8.285%).
Third: Irrigation performance indicators:
Total annual irrigation water supply (AIWS) reached 2348, 1878 and 1750 mm during the crop cycle period for fully controlled (G1), flat-roof net-house (G2) and modified Quonset (G3) systems, respectively.
Values of Annual Relative Irrigation Supply (ARIS) were 245.1, 183.3 and 148.7% for G1, G2 and G3, respectively. Irrigation water use efficiency (IWUE) for fully controlled (G1)system reached 9.75 kg/m3 while it reached 4.40 and 3.98 kg/m3 for flat-roof net-house (G2) and modified Quonset (G3) systems, respectively. The Annual Water Production (AWP) of fully controlled (G1) 137 L.E/m3 which was much higher than that of both G2 and G3 (43.2 and 33.79 L.E/m3).
The highest value of the actual irrigation water supply (IWS) (10 mm/day) was recorded in August for the three greenhouses (G1, G2 and G3) while the lowest value recorded (4mm/day) during December and January.
The estimated irrigation water requirement (IWR) values are always lower than the actual water supply (IWS) for (G1, G2 and G3), this may be is due to the limitation of using Penman Monteith model in estimating ETc (IWR) which requires the parameterization of surface canopy resistance and aerodynamic resistance which are difficult to measure in greenhouse conditions.
Fourth: Techno-economical analysis:
The construction costs of fully controlled (G1) reached 519.6 L.E/m2, while it was 24.02 L.E/m2 for flat-roof net-house (G2, meanwhile it reached 36.05 L.E/m2 for modified Quonset (G3).
Total pre-harvest costs were 46.56, 21.14 and 21.06 L.E/m2 for full controlled greenhouse (G1), flat-roof net-house (G2) and modified Quonset (G3) systems, respectively while represent 49.45, 47.71 and 51.22 % of the total production costs for the same previous order.
Total harvesting and marketing costs were 50.22, 15.59 and 11.34 L.E /m2 for G1, G2 and G3 systems, respectively, thus almost 31.77, 35.18 and 27.58 % of the total production costs for the same previous order.
Total fixed costs were 40.83, 7.45 and 8.20 L.E/m2 for three plant-house systems G1, G2 and G3 systems, respectively. Total fixed costs were 29.67, 16.86 and 20.19 % from the total production costs.
Total costs per carton (5 kg) were 40.29, 39.78 and 52.75 L.E. The total growth revenues were 323.35, 81.13 and 59.11 L.E/m2 for G1, G2 and G3 systems, respectively.
The benefit of the sweet pepper grown under the full controlled greenhouse (G1) was 185.82 L.E/m2 which represents 5 and 10 times of those grown under both net house (G2) and high tunnel (G3), respectively. The benefit-cost ratios were 1.35, 0.84, and 0.46 for G1, G2, and G3, respectively.
The break even point (B.E.P) of the sweet pepper production under the fully controlled green house system (G1) was at a rate of production of 52.3 kg which records 739.73 LE, while the BEP for G2 was at 3.31 kg which equivalents 39.00 LE. On the other hand, G3 recorded the BEP at 6.59 kg production rate which equal 66.59 LE. The pay back period for G1 was 2.28 years, while they were 0.375 and 0.95 years for both G2 and G3, respectively.
Recommendations
from the results of this study, it could be recommended with the following:
1- Integration between the environmental factors should be carried out
Further studies should be carried out on the integration between the environmental factor to reach the optimum condition to achieve the highest yield of sweet pepper.
2- Additional studies should be conducted to the investigate the effect of cover type and color on the quantity and quality of sweet pepper.
3- Mathematical model should be developed to estimate the actual water requirements of sweet pepper.