Tobacco straw biochar improved the growth of Chinese cherry (Prunus pseudocerasus) via altering plant physiology and shifting the rhizosphere bacterial community

Tobacco straws are byproducts during cigarette manufacturing, which have drawn attention for how to dispose them not at the cost of environment. Processing them into biochar might turn waste into wealth given their potentials for soil amelioration and crop growth promotion. However, the effects of biochar application are variable which severely limits their application. The aim of this study was to reveal the effect of tobacco straw biochar (TBC) on growth of Chinese cherry and the underlying mechanism. In present work, the response of Chinese cherry ‘Manaohong’ (Prunus pseudocerasus Lindl.), an economically valuable cultivar in Guizhou Province, to TBC was investigated using a six-month pot experiment. The TBC facilitated photosynthesis and uptake of nitrogen, phosphorus, potassium and manganese, and further promoted the plant growth. In addition, accumulation of endogenous phytohormones was affected. Higher level of indoleacetic acid, gibberellin A3, zeatin and lower level of abscisic acid were observed in TBC. In combination with high-throughput sequencing, the activation of indoleacetic acid and inactivation of abscisic acid signal transductions were detected at gene level, which further backed up the assumption that phytohormone signaling was affected by TBC addition. Moreover, according to our proposed pathway, majority genes for flavonoid biosynthesis were upregulated indicating that flavonoids were highly synthesized in roots in response to TBC, which reshaped the rhizosphere bacterial community by allowing growth-promoting bacteria to burgeon and suggested labile organic carbon fraction was the powerful factor for rhizosphere bacterial community shift. The results of our study partially explain the underlying mechanism of biochar-mediated growth promotion and provide crucial information for application of biochar on plants with high economic value.