Evaluation net greenhouses for tomato production in tropics [Elektronische Ressource] / von Harmanto

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Evaluation of net greenhouses for tomato production in the tropics Der Naturwissenschaftlichen Fakultät Der Universität Hannover Zur Erlangung des akademischen Grades eines Doktors der Gartenbauwissenschaften - Dr. rer. hort. - genehmigte Dissertation von Ir. M., Eng. Harmanto geboren am 23. 11. 1967 in Wonogiri, Indonesia 2006 Referent: Prof. Dr. rer. hort. habil. Hans-J. Tantau Korreferent: Prof. Dr. Vilas M. Salokhe Tag der Promotion: 31.01.2006 Contents List of Figures.........................................................................................................vi List of Tables..........................................................................................................ix List of Symbols....................................................................................................... x Summary..............................................................................................................xiv Zusammenfassung...............................................................................................xvi 1. Introduction 1 2. Literature Review 4 2.1 Greenhouse design approach for tropical region.......................................... 4 2.2 Type of insect-proof net for greenhouse ....................................................... 6 2.

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Evaluation of net greenhouses for tomato
production in the tropics







Der Naturwissenschaftlichen Fakultät

Der Universität Hannover

Zur Erlangung des akademischen Grades eines

Doktors der Gartenbauwissenschaften

- Dr. rer. hort. -




genehmigte




Dissertation






von

Ir. M., Eng. Harmanto

geboren am 23. 11. 1967 in Wonogiri, Indonesia

2006
































Referent: Prof. Dr. rer. hort. habil. Hans-J. Tantau

Korreferent: Prof. Dr. Vilas M. Salokhe


Tag der Promotion: 31.01.2006


Contents

List of Figures.........................................................................................................vi
List of Tables..........................................................................................................ix
List of Symbols....................................................................................................... x
Summary..............................................................................................................xiv
Zusammenfassung...............................................................................................xvi
1. Introduction 1
2. Literature Review 4
2.1 Greenhouse design approach for tropical region.......................................... 4
2.2 Type of insect-proof net for greenhouse ....................................................... 6
2.3 Previous works on insect-proof net used for greenhouse ........................... 10
2.4 Type and design of greenhouse ventilation openings................................. 13
2.5 Air exchange rate........................................................................................ 16
2.5.1 Measurement of air exchange rate 16
2.5.2 Estimating air exchange rate based on wind speed and chimney
effect.................................................................................................. 19
2.5.3 Simulation and Modelling to predict air exchange rate......................... 21
3. Objectives and Hypothesis............................................................................... 25
3.1 Objectives................................................................................................... 25
3.2 Hypothesis 26
4. Material and Methods....................................................................................... 27
4.1 General....................................................................................................... 27
4.1.1 Experimental site and greenhouse description..................................... 27
4.1.2 Instrumentation for measuring climate ................................................. 29
4.1.3 Crop cultivation and irrigation system................................................... 30
4.1.4 Measuring crop performance................................................................ 30
4.1.5 Measuring crop transpiration rate......................................................... 31
4.1.6 Measuring insect pest infestation (abundances) in the greenhouse..... 32
4.2 Performance of the adapted greenhouse incorporated with screen
ventilating system ...................................................................................... 33
4.2.1 Experimental set-up ............................................................................. 34
4.2.2 Data collection and analysis................................................................. 35
4.3 Simulation and modelling to predict air exchange rate and internal
microclimate............................................................................................... 35 iv
4.3.1 Measuring air exchange rate................................................................ 36
4.3.1.1 Water vapour balance method .......................................................... 36
4.3.1.2 Energy balance method .................................................................... 38
4.3.2 Development of a model to predict air exchange rate .......................... 41
4.3.3 Development of models to predict internal microclimate ...................... 43
4.3.4 Models validation.................................................................................. 46
4.4 Determination of a minimum size of ventilation openings ........................... 47
4.4.1 Experimental greenhouse 47
4.4.2 Data measurement and analysis.......................................................... 50
4.4.2.1 Air exchange rates and humidity measurements............................... 50
4.4.2.2 Air temperature rise measurements .................................................. 50
4.5 Evaluation on the effectiveness of exhaust fans used on the adapted
greenhouse................................................................................................ 51
5. Results ............................................................................................................. 53
5.1 Performance of the adapted greenhouse ................................................... 53
5.1.1 Microclimate and air exchange rate at different seasons of the year.... 53
5.1.2 Effect of net sizes on air exchange rates and microclimate.................. 59
5.1.3 Effect of mesh-sizes of nets on plant growth and yield......................... 64
5.1.4 Effect of mesh-sizes of nets on biological plant protection ................... 70
5.1.5 Water requirement (evapotranspiration) in greenhouse ....................... 73
5.2 Simulation and modelling to predict air exchange rate and internal
microclimate............................................................................................... 75
5.2.1 Air exchange rates along the experimental period of time.................... 75
5.2.2 Development of a model for predicting air exchange rate 77
5.2.3 Development of greenhouse models to predict internal microclimate .. 81
5.2.4 Influence of external wind speed and buoyancy effect on air
exchange rate.................................................................................... 87
5.3 Study on ventilation configuration of adapted greenhouse ......................... 90
5.3.1 Effect of vent opening arrangements on greenhouse microclimate...... 90
5.3.2 Effect of vent opening arrangements on crop transpiration rate........... 95
5.3.3 Effect of vent opening arrangements on air exchange rates ................ 96
5.3.4 Optimum configuration of vent opening for adapted greenhouse....... 104
5.4 Effectiveness of exhaust fans used on adapted greenhouse.................... 106
5.4.1 Performance of adapted greenhouse with exhaust fans operating
under empty condition ..................................................................... 106 v
5.4.2 Effect of operated exhaust fans on microclimate and air exchange
rate in fully tomato-grown greenhouse ............................................ 110
6. Discussions .................................................................................................... 115
6.1 General..................................................................................................... 115
6.2 Performance of adapted greenhouse in tropics ........................................ 117
6.3 Simulation and modelling in a naturally ventilated greenhouse in the
humid tropics ........................................................................................... 125
6.4 Optimum arrangement of vent opening ratio............................................. 131
7. Conclusions.................................................................................................... 134
8. Recommendations ......................................................................................... 137
References......................................................................................................... 138
Appendixes......................................................................................................... 143
Acknowledgements ............................................................................................ 147 vi
List of Figures
Figure 4.1: Isometric view of net greenhouse with different mesh sizes as
cladding material as well as roof opening.................................................. 28
Figure 4.2: Measurement of crop transpiration rate in greenhouse...................... 32
Figure 4.3: Placements of blue and yellow sticky traps in each greenhouse to
monitor insect’s infestation to the tomato crops......................................... 33
Figure 4.4: Heat and mass fluxes occurring in such a greenhouse and
measuring some climatic parameters to estimate air exchange rate ......... 39
Figure 4.5: Simplified heat and mass fluxes occurring in greenhouse assumed
as a solar collector to predict internal microclimate ................................... 43
Figure 4.6. Arrangements on closing particular vent opening of nets with an
UV-stabilized plastic film to determine a minimum size of vent ratio ......... 49
Figure 5.1: Hourly air temperatures of inside and outside the 78-mesh
greenhouse at different seasons of the year.............................................. 53
Figure 5.2: Hourly relative humidity of inside and outside the 78-mesh nt seasons of the year 54
Figure 5.3: Hourly solar radiation outside greenhouse at different seasons of
the year...................................................................................................... 55
Figure 5.4: Daily temperature and humidity difference between inside and
outside the 52-mesh greenhouse during daytime (8:00–17:00h) at
different seasons of the year ..................................................................... 56
Figure 5.5: Hourly air exchange rates averaged during daytime (8:00–17:00h)
in the 52-mesh greenhouse for different seasons of the year.................... 57
Figure 5.6: Daily temperature and hum
outside the greenhouse covered by three different net types during
daytime (8:00–17:00h)............................................................................... 59
Figure 5.7: Comparison of air temperature in greenhouses covered by three
different net types for typical day recorded on October 8, 2004 ................ 60
Figure 5.8: Comparison of absolute humidity in greenhouses covered by three
different net-types for typical dayober 8, 2004 ................ 60
Figure 5.9: Measured air exchange rates during daytime (8:00–17:00h) in
greenhouses covered by three types of nets in rainy season.................... 61
Figure 5.10: Measured air exchange rates during daytime (8:00–17:00h) in
greenhouses with different mesh-sizes of nets in cool season.................. 62
Figure 5.11: Effects of mesh-sizes of nets on plant height in greenhouse ........... 65
Figure 5.12: Weekly measurements of Leaf Are Index (LAI) and plant height
in the 52-mesh greenhouse....................................................................... 66
Figure 5.13: Weekly measurements of tomato yield from greenhouses
covered by three different mesh-sizes of nets ........................................... 67 vii
Figure 5.14: Weekly measurements of tomato quality from greenhouses
covered by three different mesh-sizes of nets ........................................... 68
Figure 5.15: Weekly variations of insect pest abundances in the greenhouses ent mesh-sizes of nets 71
Figure 5.16: Effect of mesh-sizes of nets and seasons of the year on daily
variations of evapotranspiration in greenhouse ......................................... 74
Figure 5.17: Daily variations of air exchange rate measured using two
methods in greenhouses covered by three different net mesh-sizes......... 76
Figure 5.18: Correlation between two methods in estimating air exchange rate
(N) in greenhouses covered by different net-sizes of nets in rainy
2 season (R = coefficient of determination) ................................................. 77
Figure 5.19: Comparisons between measured and predicted air exchange
rates in the 78-mesh, 52-mesh and 40-mesh greenhouses (cool
season)...................................................................................................... 78
Figure 5.20: Correlations between predicted and measured air exchange
rates in 78-mesh, 52-mesh and 40-mesh greenhouses (cool season);
2R is coefficient of determination ............................................................... 80
Figure 5.21: Correlations between wind speed and air exchange rates in the
240-mesh greenhouse in both cool and rainy seasons; R is coefficient
of determination......................................................................................... 81
Figure 5.22: Comparisons between predicted and measured internal air
temperature in the 78-mesh, 52-mesh and 40-mesh greenhouses
2(rainy season); R is coefficient of determination....................................... 82
Figure 5.23: Comparisons between pr
temperature in the 52-mesh greenhouse at three different seasons of
2the year; R is coefficient of determination ................................................ 83
Figure 5.24: Comparisons between predicted and measured internal air
humidity in the 78-mesh, 52-mesh and 40-mesh greenhouses (rainy
2season); R is coefficient of determination................................................. 84
Figure 5.25: Comparisons between pr
humidity in the 52-mesh greenhouse at three different seasons of the
2year; R is coefficient of determination ...................................................... 85
Figure 5.26: Weekly variations of the Bowen ratio (sensible to latent heat)
during experiment and heat-loss components contributed to total heat
loss in the 78-mesh greenhouse in rainy season....................................... 87
Figure 5.27: Effect of external wind speed and temperature difference on air
exchange rate in greenhouses covered by three different net-sizes of
nets in rainy season................................................................................... 88
Figure 5.28: Effect of vent ratio on means ± SE of air temperature rise and
humidity difference between inside and outside cropped greenhouse.
Means followed by the same letter are not significantly different at P =
0.05, GLM-LSD Test.................................................................................. 91
Figure 5.29: Effect of vent ratio on means ± SE
humidity differences between inside and outside empty greenhouse. viii
Means followed by the same letter are not significantly different at P =
0.05, GLM-LSD Test.................................................................................. 92
Figure 5.30: Effect of vent ratio on means ± SE of air temperature rise at
three different elevations in empty greenhouse. Means followed by the
same lower case letter within a curve and upper case letter between
curves are not significantly different at P = 0.05, GLM-LSD Test .............. 93
Figure 5.31: Effect of vent ratio on means ± SE of crop transpiration rate in
greenhouse. Means followed by the same letter are not significantly
different at P = 0.05, GLM-LSD Test ......................................................... 96
Figure 5.32: Effect of vent ratio on means ± SE of air exchange rate in fully-
tomato grown greenhouse. Means followed by the same letter are not
significantly different at P = 0.05, GLM-LSD Test...................................... 97
Figure 5.33: Effect of vent ratio on means ± SE of air exchange rate at two
conditions (natural vs. force ventilation) in empty greenhouse. Means
followed by the same letter are not significantly different at P = 0.05,
GLM-LSD Test........................................................................................... 98
Figure 5.34: Relationships between temperature rise and air exchange rate in
fully-crop greenhouse at different ventilation arrangements .................... 100
Figure 5.35: Relationships between wind speed and air exchange rate in fully-
crop greenhouse at different ventilation arrangements............................ 100
Figure 5.36: Relationships between wind speed and air exchange rate in
empty greenhouse at different ventilation arrangements......................... 103
Figure 5.37: Effect of vent ratio on means (± SE) of absolute humidity
difference in greenhouse under two conditions. Means followed by the
same letter are not significantly different at P = 0.05, GLM-LSD Test ..... 105
Figure 5.38: Daily variations of air temperature rise due to exhaust fans
operation in the 78- and 40-mesh greenhouses in empty condition ........ 107
Figure 5.39: Daily variations of air exchange rate due to exhaust fans ........ 107
Figure 5.40: Effect of exhaust fans operations on air exchange rate and
temperature rise in the 78-mesh, 52-mesh and 40-mesh greenhouses
in empty condition.................................................................................... 109
Figure 5.41: Effects of exhaust-fans operation on internal air temperature in
cropped greenhouses (NV = natural ventilated, FV = force ventilated
greenhouse) ............................................................................................ 111
Figure 5.42: Effects of exhaust-fans operation on absolute humidity in es
greenhouse) 112
Figure 5.43: Effects of exhaust-fans operation on air exchange rate in the 78-
mesh and 40-mesh cropped greenhouses .............................................. 112
Figure 5.44: Effects of exhaust-fans operation on crop evapotranspiration
(ET ) in the 78-mesh and 40-mesh cropped greenhouses...................... 114 Cix
List of Tables
Table 2.1: Screen hole sizes required to exclude several insect pests .................. 6
Table 4.1: Design parameters used for computation of air exchange rate ........... 43
Table 5.1: Mean (± SE) of microclimate and air exchange rate in the 52-mesh
greenhouse during daytime at different seasons of the year ..................... 58
Table 5.2: Mean (± SE) of air exchange rate, air temperature, relative
humidity and absolute humidity difference during daytime (8:00–
17:00h) in the 78-mesh, 52-mesh and 40-mesh greenhouses .................. 63
Table 5.3: Mean (± SE) of air exchange rate, air temperature and absolute
humidity difference during daytime (8:00–17:00h) in the 52-mesh
greenhouse at three different seasons of the year .................................... 64
Table 5.4: Mean (± SE) of weekly plant growth rate, total yield and tomato
quality in the greenhouses covered by three different mesh-sizes of
nets and in the 52-mesh greenhouse at different seasons of the year ...... 69
Table 5.5: Effect of seasons of the year on tomato yield and fruit quality in 52-
mesh greenhouse...................................................................................... 70
Table 5.6: Mean (± SE) of weekly insect pest population flying in greenhouses
covered by three different net-types in the cool season............................. 72
Table 5.7: Mean (± SE) of weekly insect disease population flying in the 52-
mesh greenhouse at different seasons of the year.................................... 73
Table 5.8: Effect of mesh size and seasons of the year on mean (± SE) of
evapotranspiration in greenhouse ............................................................. 75
Table 5.9: Statistical analysis to correlate between air exchange rate vs.
temperature rise and wind speed using the Spearman rank-test at
different arrangements of ventilation ratio (V )......................................... 102 r
Table 5.10: Statistical analysis to evaluate operated exhaust fans on air
exchange rate and temperature rise using t-test ..................................... 108
Table 5.11:is to evaluate operated exhaust fans on some
selected parameters using t-test.............................................................. 113

x
List of Symbols
2A cover surface area [m ] c
2A floor area [m ] f
2A soil surface area ] g
2A effective vents opening area [m ] o
2A roof area ] r
2A side ] s
a constant of predicted air exchange rate [ - ]
-1C gas concentration [kg kg ] (gas) (air)
-2 -1C condensation rate on ground or crop [kg m s ] con (water)
C discharge coefficient [ - ] d
-2 -1C convective heat exchange coefficient [W m K ] h
-1C inside gas concentration [kg kg ] i (gas) (air)
-1C outside gas kg ] o (gas) (air)
-1 -1c specific heat transfer of air [J kg K ] p
C wind speed coefficient [ - ] w
dC variation of gas concentration during a time i
-1 interval [kg kg ] (gas) (air)
dt time interval [s]
-3dX water vapour difference [kg m ] i
-2 -1E soil evaporation [kg m s ] s (water)
-2E crops evapotranspiration (latent heat) [W m ] T
-2 -1F water supply into the greenhouse (misting) [kg m s ] (water)
-2F soil thermal flux [W m ] g
-3 -2 -1G ventilation rate per unit greenhouse floor [m m s ]
-2g acceleration of gravity [9.81 m s ]
H height of vent opening above the floor [m]
-2H energy loss to the greenhouse wall [W m ] c
-2H sensible energy gain [W m ] s
-2H energy loss due to ventilation [W m ] v
-2 -1K global sensible heat loss coefficient [W m K ]
-2 -1K coefficients of heat transfer by ventilation [W m K ] v