Response of summer savory at two different growth stages to biochar amendment under NaCl stress

Salinity stress leads to various biochemical changes in plants. Biochar (BC) is a soil amendment that is derived from pyrolyzed organic materials. The aim of this study was to investigate the effect of BC on growth and some biochemical characteristics of summer savory (Satureja hortensis L.) under NaCl stress at two different growth stages. So, a pot factorial experiment based on completely randomized design was performed that comprised three levels of BC (0, 1 and 2% w/w of soil) and four NaCl levels (0, 40, 80 and 120 mM) with four replications. According to the results, by increasing the NaCl concentration chlorophyll a, b, total chlorophyll, carotenoid and polyphenol oxidase (PPO) decreased, whereas antioxidant activity, total soluble sugar and phenolic contents increased. The use of BC (especially 2% w/w of soil) under NaCl stress had the greatest effects on studied traits at the vegetative and flowering stages and significantly increased chlorophyll a, b, total chlorophyll, carotenoid and PPO activity. The results of this experiment confirmed the view that each stage of growth responses differently to NaCl stress and the use of BC due to sorption of NaCl and increasing osmotic adjustment can lead to summer savory protection against NaCl stress.