Effect of solarization and vesicular arbuscular mychorrizal on weed density and yield of lettuce (Lactuca sativa L.) in autumn season

This study was conducted on trial field of Faculty of Agriculture, Dicle University, Diyarbakir, Turkey in 2007 growing season. The experiment established on a loamy- clay soil with the seedlings of Yedikulelettuce (Lactuca sativa L.) infected by Vesicular Arbuscular Mychorrizal (VAM) fungus, Glomus intraradices. The goal was to increase the yield and quality in lettuce production. The VAM infected and disenfected lettuce seedlings propagated in greenhouse conditions were planted by the split-plot designs-random model. The study was conducted as the main plot applied solarization and nonsolarization and subplot with VAM and without VAM which resulted in four repetitions. The solarized field had an increased soil temperature: the increase in the temperature was 11°C in 5 cm depth, 8°C in 20 cm and 5°C in 30 cm. This situation continued to the end of the growth season and also inhibited the germination of weed plants. In the solarized area, the plant height, plant crown-width and yield showed significant increase during the vegetative season of 45 days long. The data was significant for three growth factors. In solarized area, the average weight of lettuce was obtained to be 138.85 g but in control parcel the average weight was 30.85 g. The increases in VAM parcel for three growth factors were significant. But the interaction between solarization and VAM was found non significant. To determine VAM before testing in laboratory, VAM dutied like a bridge from donor lettuce to receiver wildmustard (Sinapsis arvensis L.) as observed in the experiment because mustrad has no symbiosis life with this fungus. Also the laboratory findings supported this; the number of spores, number of VAM infected and infection rate were higher both in main parcel of solarized and in the subplot parcel planted with VAM seedlings than the nonsolarized parcel and non VAM seedlings. The results for both criteria were significant in solarization and VAM application. But the interaction with VAM andsolarization was insignificant. As a result, one can note that the VAM inoculation after solarization application is beneficial for growing lettuce especially in the fall of season