An Investigation into the Effect of Humic Acid Application on Some Morphological and Physiological Characteristics of China Rose

In recent years, excessive use of chemical fertilizers and lack of organic fertilizers have caused to reduce the rate of soil organic matter in Iran. The increased use of chemical fertilizers in agriculture causes environmental problems such as soil physical degradation and soil nutrient imbalances. This study was conducted to investigate the effects of foliar and soil application of humic acid on some morphological and physiological characteristics of Rosa􀀀 chinensis ‘Baby Masquerade’ in a completely randomized design with two factors including four concentrations of humic acid (0, 500, 1,000 and 2000 mg/L) and two application methods (soil and foliar application) for 8 times (every 15 days) with three replications and two observations per replication under controlled greenhouse conditions. The results showed that humic acid had additive effects on anthocyanin and total soluble solids content. It should be noted that the increase in the content of total soluble solids resulted in the increase in anthocyanin. Foliar application of 500 mg/L humic acid significantly increased chlorophyll content and photosynthetic rate. Also, foliar application of 1000 mg/L humic acid improved total soluble solid content more than the other treatments. Humic acid had significant effects on leaf area index and shoot and root fresh and dry weight. Overall, it seems that humic acid can improve morphological and physiological characteristics of Rosa􀀀 chinensis var. ‘Minima’.