Greenhouse structures in Mediterranean regions: Problems and trends

Transcription

1 Greenhouse structures in Mediterranean regions: Problems and trends Grafiadellis M. in ChoukrAllah R. (ed.). Protected cultivation in Mediterranean region Paris : CIHEAM / IAV Hassan II Cahiers Options Méditerranéennes; n pages 1727 Article available on line / Article disponible en ligne à l adresse : To cite this article / Pour citer cet article Grafiadellis M. Greenhouse structures in Mediterranean regions: Problems and trends. In : ChoukrAllah R. (ed.). Protected cultivation in Mediterranean region. Paris : CIHEAM / IAV Hassan II, p (Cahiers Options Méditerranéennes; n. 31)

2 Abstract: 35 been noticed in plastics films, development some and this expansion. Today a developed in China, Japan and ha o in applications is middle 19th glasshouses in scale in noticed. With plastics films in a in table1 evolution to this table, Spain is is to (1 995) to ha out which ( ha in Themain whichhaveinfluenced hugeexpansion followings: e The climatic advantages 0 sunny days with high intensities The possibilities using low (wood, steel, plastic sheets). c The high heating cost The VOL 31 17

3 Table 1. Greenhouses and high tunnels in 2605 Spain Ex. Yugoslavia 2000 Lebanon Libya 7 Tunisia 1425 Albania? Total in table 2 it can be that in is is also well known that in se not heated and mainly employed in vegetables while most glasshouses used in Table 2. The evolution greenhouses countries Spain Ex. Yugoslavia Tunisia Glasshouses (ha) L Adapted fiom Grafiadellis 1987; Castilla high ' The most plastic in long life polyethylene films and only films and mainly films found big applications. (Nisen et al, 1990). vol

4 plastic panels made l m to 14mm thick, 0.9 thick and 6mm thick used. TYPES OF to local climatic conditions, customs, in developed (Nisen et al 1990; ElAidy 1991; 1985; 1992). saddle side walls, side walls and book 1986; Nisen et al 1990; 1984; Zabeltitz 1990). single span side walls (fig. 1 and fig.2). _. A single span round arched','greenhouse (FAO booklet, greenhouses in Syria)..,... i.i / I ,.,. '.?.. Fig. 2 A round arched greenhouse with vertical sidewalls (FAO ;.. greenhouses in. vol

5 in greenhouse types made wood steel side walls mainly used (fig.3, fig.4)..fig. 3':A,sddle'm greenhouse type rnade.fri3m'wood and.steel pipes Crete. (FAO..Fig. 4 A.saddk.. greenhouse.. type used in:sic&'(faq book).. in Spain linked one to at film is sandwiched vol

6 (fig.5). The last Figure 5. Parral type greenhouse in Almeria, Spain (FAO book) type plastic above and below wooden sticks in is mainly used (fig.6). this type to be single span to to multispan. Figure 6. Wooden greenhouse type in Portugal (FAO book) been developed, some which saddle (fig.7) shed (fig.8) ventilation (fig. 9). Cahiers VOL 31 21

7 . '.. ' 1,...,..... _".... Figure 7. A saddle ro type greenhouse (FAO book) Fig. 9. A type greenhouse with roiling up ridge ventilation in greenhouses in Cyprus). (FAO booklet, Cahiers Options 31 22

8 ln most 1 O). Fig. 10 Pointed arched type greenhouse in (FAO booklet). Themaintechnicalproblems,whichstructures regions face, are: The biggest enemy plastic wind. The huge in wind speeds something exceed 4045ds ( that in some cases winds al Finn 1992). to been designed to 34ds 25kg/m2 and a plant weight 20kg/m2 (Vadiou 34ds wind speeds, obliged to take such as use to to to to al et al 1978; FAO book 1987). A second big enemy is snow load. to withstand a load 25kg/m2. snow falls usuallyexceed take Finn sensitive to 1987). to avoid damages big snow loads, top 1992). in mainly not taking to Cahiers Options vot

9 b) The shape and slop ro greenhouses. that to than (JaEin 1990; al 1995; FAO in low in et al, 1990). As as is well known that it effects f movement inside FAO slops such 28" as minimums. c) The dimensions and sizes greenhouses. done by institutions and that side walls ventilation, mechanization development tall (FAO 1987; Nisen et al to height side walls at least 260 in in m3/m2 (Nisen et al, 1990). side walls, too many many cases (Nisen et al, 1990). too d) light is in size shape and small slops. (Castilla 1994; FAO 1987; Jafiin e) Ventilation. Almost all adequate ventilation. The that in between opening and should be at least 2225% and that multispan which et al, 1984). also found some f) The plastic films. scientists and that polyethylene films at plastics should not be to be changed, should have as as optical be et al 1990; Zabeltitz 1990). g) The collection rainwater by greenhouse gutters. that is bed quality, it is to mix it with collected by I Cahiers Options 31 24

10 h) The cost greenhouse structures. that in not always economical ones applications and its effect on cost has et al, 1995). NEW OF to in 7900 table 2 it can be that tendency is Today etc. as high as that to As as shapes to to in also to on to to minimize to shapes etc. ventilation tendency is openingseven40%and mechanization mainly side ones. although has is to be adapted. gaining antifogging due to to some technical also found some applications only The collection and use to high cost has applications. pushed to Arbel, A., Segal, Yekutieli, O. and Zamir, : Bailey, B.J., Brun, and J., adapted to conditions. Acta 170:

11 Castilla, N. J., in 107:1320. Castilla, and Grafiadellis, A study field Grailadellis, in XXV, th annual meeting ElAidy, F., Egypt. 92(4):3340. FAO book., in FAO, ppl26. to climatic conditions FAO book, in FAO, ppl32. Grafiadellis, A study Grafiadellis, a passive 191~ Grafiadellis, Goldsberry., Jaffrin, A. and Urban, Optimisation The influence Nisen, A., P.F., O., U. and Baudoin, W.O., cultivationin Preben, and Finn B., FAO Technical Sadao, N., Japan. 108 (4):312. Cahiers Options vol. 31

12 Sirjacobs Use new types plastic tunnels for Acta Triki, J., Verlodt, and Baeten, S., la sous Acta 154: Tmuramaai, and GdadeW, Vassiliou, N., companies points view. FAO Waaijenberg, by wind, snow FAO Zabeltitz, C.V., film Acta 154: Zabeltitz, C.V., ~ function 27