Due to its importance for organic agriculture, one of the most important agricultural production systems, various sources have been proposed to increase soil organic matter content. Vermicompost is one of those sources known as the resistant last form of farmyard manure which is degraded by earthworms. Soil organic matter or humus and their compounds are nutrient sources that increase physical, chemical and biological quality of soil. Humus and humus compounds improve soil physical, chemical and biological quality parameters increasing rhizosphere aeration and water holding capacity, rehabilitating soil structure, providing plant nutrients and constituting natural media for microorganisms with their regulative effects on soil reactions. In this study, the effects of vermicompost on yield and some growth parameters of lettuce were investigated. For this purpose, a random block designed experiment with 5 different applications was conducted in 3 replicates. The applications were control, vermicompost applications of 100 kg, 200 kg and 300 kg per decare and conventional fertilization. According to the results obtained, yield and growth parameters were improved by vermicompost application when compared to control and conventional fertilization. As a result of this study, it was concluded that 300 kg vermicompost/da is a promising application in lettuce production for optimal yield and soil improvement.

Genetic polymorphism amid plant species is a crucial factor for plant improvement and maintaining their biodiversity. Evaluation of genetic diversity amongst plant species is significant to deal with the environmental stress conditions and their effective involvement in the breeding programs. Hence, in present study, an attempt has been made towards the genetic assessment of individual and bulked populations of 25 watermelon genotypes, belonging to Citroides (citron watermelon) and Lanatus (dessert watermelon) group from Konya, Thrace, Turkmenistan, Saudi Arabia and Turkey. The employed Random Amplified Polymorphic DNA (RAPD) and Inter-Simple Sequence Polymorphism (ISSR) marker systems provided 69.4 and 95.4% polymorphisms, respectively. Different clustering methods showed clear grouping of the genotypes based on the geographical origin and species. Citron genotypes from Turkmenistan stood apart from all the Turkish Lanatus genotypes. However, Saudi Arab Lanatus genotype grouped with native Turkish varieties indicating the genetic linkage. Among all the Turkmenistan Citron genotypes, Turkmenistan-11 was the most distinct form. Moreover, sufficient genetic variation was found between the commercial and native Lanatus genotypes of Turkey as well as Citron genotypes of Turkmenistan. Hence, it will be beneficial to include these genotypes in the future breeding programs to transfer disease-resistant alleles from Citron to Lanatus genotypes.