Effects of Different Heating Systems on Cucumber Yield in Greenhouses and Cost and Gas Volume Consumed in Varamin Region

This research was conducted to investigate the effects of three heating systems on cucumber yield,and cost and gas volume consumed in greenhouses located in Varamin region,Tehran province,Iran.Conventional heating systems used in the greenhouses are:central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases).The study was carried out for two consecutive cucumber cultivation periods from January to June.Average values of crop yield,volume and cost of gas consumed were determined separately for each heating system.Results of the study indicated that the central heating system with the highest crop yield(295 t/ha),and the lowest volume(100,000 m^(3)/ha)and cost(840 USD/ha)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.

Effect of Different Heating Systems in Cucumber Production Greenhouses in Varamin Region on Crop Yield, Volume and Cost of Gas Consumed

This research was conducted to study the effect of different heating systems in cucumber production greenhouses in Varamin region,Tehran province,Iran on crop yield,volume and cost of gas consumed.Three types of conventional heating systems,namely the central heating system(including boiler+hot water pipes),gas heater system(including double-walled tank+blower)and traditional furnace system(including ignition chamber+torch+pipes carrying a mixture of hot air and flammable gases)were studied during two consecutive periods of greenhouse cucumber cultivation in the cold season(from January to June),and average values of crop yield,volume and cost of gas consumed were determined separately.Results of the study indicated that the central heating system with the highest crop yield(295 tžha^-1),and the lowest volume(100,000 m3žha^-1)and cost(210,000,000 Rialsžha^-1)of gas consumed was the best and most suitable heating system for greenhouses producing cucumbers in Varamin region and other regions with the same and similar climate as well as regions with active greenhouses in the cold season.

Larval development and voracity of Eupeodes americanus (Diptera: Syrphidae): comparison of the focal prey Aphis gossypi (Hemiptera: Aphididae) and the banker prey Rhopalosiphum padi (Hemiptera: Aphididae)

Unlike European species,the potential of Nearctic syrphids as biological control agents is still poorly studied.However,the American hoverfly,Eupeodes americanus(Wiedemann),has recently demonstrated promising traits as a biocontrol agent,notably against the foxglove aphid,Aulacorthum solani Kaltenbach,on pepper.The present study aims to extend our knowledge of the American hoverfly by evaluating its potential as a biocontrol agent in a banker plant system against the melon aphid,Aphis gossypi Glover,in a greenhouse cucumber crop.The preimaginal development and voracity of E.americanus were compared when preying upon the focal prey/pest(A.gossypi)or the banker prey(bird cherry-oat aphid,Rhopalosiphum padi L.)by daily observations of larvae from egg to adult.Preimaginal development time,survival rate,and occurrence of deformation were similar on both prey species.The weight of third instar and pupae,however,was higher for larvae that fed on the banker prey.The ad libitum voracity of the syrphid larvae was generally very high and did not significantly differ between prey species,except for the third-instar larvae which consumed more focal prey.Results suggest that a banker plant system involving the bird cherry-oat aphid may be a promising tactic for utilizing E.americanus for melon aphid biocontrol.