Nowadays, the use of humic acid and chitosan as natural stimulator substances has increased. They have specific properties ofbeing environmentally friendly and easily degradable. Humic acidis a suspension, based on potassium humates, which can be sprayeddirectly to the plant foliage in liquid form as a plant growth stimu-lator. It stimulates plant growth by acting on mechanisms involvedin cell respiration, photosynthesis, protein synthesis, water andnutrient uptake, enzyme activities (Nardi et al., 2002; Zhang andErvin, 2004). Many researchers concluded the enhancing effect ofhumic acid on growth, nutrient uptake and yield of bean plants.Kaya et al. (2005) pointed out that foliar spray of humic acid at 3to 6 leaf stage significantly increased yield and yield componentsin common bean. Ahmed et al. (2010), EI-Bassiony et al. (2010)and Fawzy et al. (2010) found that foliar application of humic acidimproved significantly the plant growth, yield and physiologicalprocesses in snap bean.