Calcium and humic acid affect seed germination, growth, and nutrient content of tomato (Lycopersicon esculentum L.) seedlings under saline soil conditions

The effects of calcium and humic acid on seed germination, growth and macro- and micro-nutrient contents of tomato (Lycopersicon esculentum L.) seedlings in saline soil conditions were evaluated. Different levels of humic acid (0, 500, 1000 and 2000 mg kg(-1)) and calcium (0, 100, 200 and 400 mg kg(-1)) were applied to growth media treated with 50 mg NaCl kg(-1) before sowing seeds. Seed germination, hypocotyl length, cotyledon width and length, root size, shoot length, leaf number, shoot and root fresh weights, and shoot and root dry weights of the plant seedlings were determined. Macro- and micro-nutrient (N, P, K, Ca, Mg, S, Cu, Fe, Mn and Zn) contents of shoot and root of seedlings were also measured. Humic acid applied to the plant growth medium at 1000 mg kg(-1) concentration increased seedling growth and nutrient contents of plants. Humic acid not only increased macro- nutrient contents, but also enhanced micro-nutrient contents of plant organs. However, high levels of humic acid arrested plant growth or decreased nutrient contents. Levels of 100 and 200 mg kg(-1) Ca2+ application significantly increased N, Ca and S contents of shoot, and N and K contents of root.