Effect of solarization on weeds in greenhouse tomatoes and tomato yield in East Mediterranean region of Turkey.

Severe yield losses can be occurred by infestation of weeds in tomato cultivation. This study was carried out to determine the effect of solarization against weeds and tomato yieldin two different tomato greenhouses in Adana province of Turkey between the years 2007-2008. Solarization was performed by using transparent polyethylene cover (0.025 mm thickness) for a period of 8 weeks during August and September 2007 in two greenhouses. To investigate the effect of this application on weeds; the number of weeds and tomato yield were compared with non-solarized plot in this study. It was found out that solarization treatment increased maximum soil temperature more than 10 oC (13-14 oC) at 5 cm depth of soil and a temperature more than 50 oC (51-53 oC) was reached for 8 weeks in two greenhouses. As a result of the study, effect of solarization on general weed densities was determined as 42%. Common weeds in the greenhouses were Purple nutsedge ( Cyperus rotundus L.), Bristly foxtail ( Setaria verticillata (L.) P. Beauv.), Smooth pigweed ( Amaranthus hybridus L.) and Branched broomrape ( Phelipanche ramosa L.). Solarization has found to be effective to S. verticillata, A. hybridus and P. ramosa at the rate of 92, 90 and 97%, respectively, opposite to C. rotundus which it had no effect on this weed,  and tomato yield was increased 24-27% in solarization treatment compared with the non-solarized treatment. As result, solarization for 8 weeks reduced amount of many annual weeds including a parasite weed species, Phelipanche ramosa, and increased crop yields. Based on these results, soil solarization can be recommended to control of some weed species in greenhouse areas.