The effects of inoculation of rhizosphere-promoting bacteria (PGPR) on photosynthesis and physiological-ecological characteristics of apple tree seedlings under drought conditions were investigated in this study, aiming to provide a theoretical basis for the application of PGPR in plant drought resistance. In the pot experiment, the rhizosphere-promoting bacterium YX2 which had both ACC deaminase activity and strong phosphorus solubilizing ability was selected as the tested strain. Apple seedlings were grown under four different irrigation levels i.e., control (CK), mild drought (LD), moderate drought (MD), and severe drought (SD) with soil moisture equivalent to 70%-80%, 55%-65%, 40%-50% and 25%-35% of field water holding capacity, respectively. Inoculation of PGPR alleviated the damaging effects of drought on growth by improving relative water content and chlorophyll content in apple tree seedlings. In addition, PGPR inoculated individuals exhibited higher antioxidant enzyme activity, chlorophyll fluorescence values, stomatal conductance and photosynthetic rate and lower relative conductivity and lipid peroxidation. Our results suggested that PGPR-YX2 alleviated the negative effects of drought stress on the growth and net photosynthetic rate by improving the antioxidant system, water content and membrane functioning.
本试验研究了接种根际促生细菌(PGPR)对干旱条件下植物光合和生理生态特性的影响,以期为PGPR在植物抗旱中的应用提供理论依据.采用盆栽试验,以苹果实生幼苗为供试植物,以经过筛选得到的既具有1-氨基环丙烷-1-羧酸(ACC)脱氨酶活性又具有较强溶磷能力的根际促生菌YX2为供试菌株,设置正常水分(CK)、轻度干旱(LD)、中度干旱(MD)和重度干旱(SD),其相应含水量分别为田间持水量的70%～80%、55%～65%、40%～50%、25%～35%,研究不同程度干旱胁迫条件下接种YX2对苹果实生幼苗光合和生理生态特性的影响.结果表明: 与未接种处理相比,干旱环境下接种YX2提高了苹果幼苗叶片的相对含水量、叶绿素含量、抗氧化酶活性、叶绿素荧光值、气孔导度和光合性能,降低了相对电导率、渗透调节物质和丙二醛的积累,缓解了干旱胁迫对净光合速率的抑制,增强了抗氧化系统的防御能力,减少了细胞膜过氧化伤害,提高了植株抗旱性能.
Keywords: apple seedling; drought stress; photosynthesis; physio-logical and biochemical characteristic; rhizosphere-promoting bacteria.