The application of Biochar with Humic acid for resistance to drought stress in Zinnia

Using of humic acid and adding Biochar to soil could be used as an effective way to reduce the harmful effects of drought stress in Zinnia elegans. The effects of three factors: biochar (three levels 0, 20 and 40 g / kg of potting soil), humic acid (three levels 0, 250 and 500 mg / L, soluble) and two irrigation levels (50 and 100% crop capacity)was investigated in this experiment. According to the results, drought stress reduced the amount of chlorophylls, content phosphorus and potassium leaves, but increased amount carotenoids, ion leakage, proline, nitrogen and magnesium elements. The use of Biochar increases potassium and ion leakage. Humic acid reduced the content of proline in the studied plants, reducing the drought stress. The effect of Biochar and humic acid on the amount chlorophyll a and total chlorophyll, nitrogen and phosphorus were significant. The use of humic acid causes confront with drought stress and its use under drought stress conditions is recommended. The use Biochar is advisable in lack of phosphorus and nitrogen elements.