The study was conducted to investigate the effects of organic fertilizers and mulches on the growth and CO₂ assimilation in MM.106 apple trees. Growth and CO₂ assimilation of MM.106 apple trees grown in a greenhouse were affected by the nutrient concentrations and carbon (C) and nitrogen (N) ratio in the raw materials of organic fertilizers and mulches. The optimum C:N ratios, which makes microorganism convert the organic N into the inorganic N, were obtained in the organic fertilizer, poultry litter, green compost, and grass clippings, resulting in increasing single shoot height, SPAD, and CO₂ assimilation. The SPAD and CO₂ assimilation were affected by the treatments 5 weeks after the treatments, and then the tree growth was affected by the treatments 6 weeks later. The most efficient tree growth and development were observed in the 10 to 15 ㎎ㆍ㎏⁻¹ of the inorganic N in a soil, and the N was strongly related to the tree growth and development.