Effects of trichoderma harzianum applied at seed sowing medium on seedling quality of some vegetable crops

In order to determine the effects of Trichoderma harzianum on seedling growth and quality, two consecutive treatments were carried out in the spring of 2018. In the first experiment, four different T. harzianum strains were used in tomato seedlings by comparing with one commercial T. harzinum preparate and the control group with out treatment. The most promising strain (strain2), was selected and used in tomato, cucumber and lettuce seedlings in second treatment. To determine the effect of T. harzianum application with the use of foliar fertilizer, strain + fertilizer (20-20-20) and strain + non-fertilizer treatments were tested. The treatments were compared with the control seedlings which were foliarfertilized but not T. harzianum strain. Seedling length, root length, stem diameter, leaf thickness, fresh and dry weights of root and vegetative parts, dry matter content, color, chlorophyll content, leaf macro and micro element contents and quality index were determined in the seedlings which were ready for planting. Data obtained from the first experiment showed that the effects of different T. harzianum strains on seedling morphology, physiology and nutrient content were different. Among the used strains, strain2 isolated from rhizosphere of green house tomato plants in Ceyhan district of Adana showed better performance on seedling height, root and shoot dry matter contents, total fresh weight, chlorophyll, a color valueand P, Ca, Mn, Cu and Zn element contents of leaf than other strains and improved seedling quality. The result sobtained from the second experiment showed that the effect of T. harzianum on seedling growth and quality may vary according to species; as well as growing conditions, production period and cultural practices can be effective in this regard. The foliar fertilizer in creased the efficiency of T. harzianum strain2 in all three species. T. harzianum strain2 alone was remained below the control application in all measured parameters. When all the data obtained were evaluated together, it was concluded thatT. harzianum could be used to increase seedling quality due to its positive effects on seedling biomass, element uptake and quality index, although its effects change according to the plant species and strain used. Moreover, it can be used organic seedling production as alternative biostimulant.