Effects of plant growth promoting microorganisms on yield and quality parameters of lettuce (Lactuca sativa L.)

This study was conducted to determine the effects of plant growth promoting microorganisms on yield and some quality attributes of 'abbice' crisp lettuce variety. tested treatments were applied via drip irrigation at a dose of 10 ml / l perla vita,as water (95%) and molasses (5%) mixture of lactobacillus casei (107),lactobacillus plantarum (107),rhodopseudomonas palustris (105),and saccharomyces cervisiae (103)] four times as 1,2,3 and 4 weeks after planting the lettuce seedlings. the lettuces in the control did not receive any treatments. head weight,diameter and height,unmarketable and marketable leaf weight and number,leaf number,root crown diameter,stem length and thickness,and leaf colour (l*,a*,b*) were determined in harvested plants. treatment with plant growth promoting microorganisms increased head weight and diameter by 7.4% and 6.2%,respectively compared to the control plants. applications also increased marketable head and leaf weight by 12.0 % and 12.1%,respectively. unmarketable leaf number and weight were lower (2.8 leaves/head and 11.4 g/head) in treated plants than the untreated lettuces (3.8 leaves/head and 22.3 g/head). effects of tested microorganisms on other quality parameters showed similarity with control group. the results displayed that plant growth promoting microorganism treatments increases head weight and diameter,marketable head and leaf number whereas decreases unmarketable leaf number and weight.