Phosphorus and humic acid application alleviate salinity stress of pepper seedling

Humic acid is a commercial product that contains many elements which improve the soil fertility and increase the availability of nutrient elements. It consequently affects plant growth and yield and ameliorates the deleterious effects of salt stress. The objective of the study was to determine the effect of humic acids and phosphorus on growth and nutrient content of pepper seedlings (cv. Demre) grown under moderate salt stress in growth chamber conditions. Applications of different levels of phosphorus [0 (P(0)), 50 (P(1)), 100 (P(2)) and 150 (P(3)) mg kg(-1)] and humic acid [0 (HA(0)), 750 (HA(1)) and 1500 (HA(2)) mg kg(-1)] to growing media containing moderate salt dose (8 mM NaCl treatment) were studied. The study was replicated four times with 20 plants in each replicate. Humic acid (HA) and phosphorus applications increased the growth and growth parameter of plants. In company, effects of HA and P application was more effective on growth and growth parameter than each separate effect. The optimum total yield was obtained from 69 mg kg(-1) P application with HA2 doses according to regression analysis. Humic acid application significantly increased N, P, K, Ca, Mg, S, Mn and Cu contents of shoot of pepper seedling. Also, N, P, K, Ca, S, Fe, Mn, Zn and Cu contents of root were increased with humic acid application. Na contents of both shoot and root of pepper decreased with increased humic acid doses. It can be concluded that high humic acid doses has positive effects on salt tolerance based on the plant growth parameters and nutrient contents. The present study suggests that HA treatments can ameliorate the deleterious effects of salt stress on pepper plants and HA could offer an economical and simple application to reduce problems of pepper production in moderately saline soil.