Effect of low temperature stress and INA bacteria on parameters of photosynthesis and chlorophyll fluorescence in loquat leaf

Freezing injury is a major factor that influences and restricts loquat’s production and development. In this experiment, the effects of INA (ice nucleation active) bacteria inoculation on photosynthetic and chlorophyll fluorescence parameters of the leaves of “Zaozhong No.6” loquat under low temperatures were investigated. The results show that INA bacteria significantly reduces Pn, Fm, Fv, Fv/Fo, Fv/Fm and water use efficiency under low temperature. This indicates that INA increases degradation of photosynthetic apparatus, which in turn limits photosynthetic activities under low temperatures. INA bacteria inoculation under -3 ℃ more significantly and earlier influences Pn, Fm, Fo, Fv, Fv/Fo and Fv/Fm than under -1 ℃. This implies that the lower the temperature, the greater and the earlier the damage caused by INA bacteria to photosynthetic system. Furthermore, it is noted that Tr is not associated with the presence of INA bacteria.