Study of fat compost from dairy industry wastewater as a new substrate for pepper (Capsicum annuum L.) crop

• 1- FC extract, resulting free of phytotoxicity for seeds germination.
• 2- Higher doses of FC improved of yield and characteristics of pepper fruit
• 3- FC not increased the heavy metals concentration of pepper fruit.

The aim of this study was to analyze the impact of different doses of compost obtained from fats waste of dairy industry mixed with commercial peat-based substrate and with soil on pepper plants development. Furthermore, this investigation attempted to determine the effects of these mixtures on germination and composition of pepper fruits. Fat compost (FC) was obtained by aerobic composting from dairy industry wastewaters mixed with wood chips and green grass. FC extract resulted free of phytotoxicity for seed germination, obtained 99.71% the relative seed germination and 74.10% of germination index. Different growing media were prepared by mixing 0, 10, 20 and 40% of FC with commercial substrate (CS) or Soil in two different experiments. Results showed that the application of FC on CS and Soil respectively, increased plant dry matter. On pepper seedling FC 40 achieves 250 mg plant−1 DM. Moreover, higher doses of FC improved yield and several characteristics of fruit as dry matter, diameter and concentrations of some carotenoids. The incorporation of FC did not increase the heavy metals concentration of pepper fruit. At leaves, the highest concentrations of N were reached shown on treatment with FC (Soil: 1.46%, FC 10: 1.92%, FC 20: 2.00%, FC 40: 2.09%). Application of FC for germination and development of pepper plants improved the seedlings, fruit yield and quality.