Effects of 5-aminolevulinic acid on cutting growth under high temperature condition and leaf chlorophyll fast fluorescence characteristics of Ficus carica L.

[Objectives] The aim of this study is to discuss the effects of 5-aminolevulinic acid (5-ALA) on fruit tree cutting. [Methods] The cuttings of fig (Ficus carica L. 'Brunswick') were sprayed with 0.05, 0.10 and 0.20 mg.L-1 5-ALA solutions when they were 20 cm high to study the effects on the young plant growth and the leaf chlorophyll fast fluorescence characteristics with a M-PEA (multi-function plant efficiency analyser) instrument under high temperature condition. [Results] The results showed that all ALA treatments improved the cutting survival rate under high temperature condition, and promoted plant growth with higher levels of soluble sugars, soluble proteins and starch content in the shoots and roots of cuttings. The OKJIP transient analysis showed that 5-ALA treatments increased phase I of the leaf chlorophyll fast fluorescence curves, with obvious "V" type L band and K band. When t = m, the energy of absorbance (ABS/CSm), trap (CRyCSm) and electron transport (ETo/CSm) cross section, and the density of active reaction centers of PS II(RC/CS) were increased significantly in the 5-ALA treated leaves, while the inhibition of oxygen evolving complex (Wk) and the maximum close rate of PS II reaction center (Mo) were decreased, but the capacity indexes including PIABS and PICS were improved. These suggest that 5-ALA at low concentrations can increase light absorbance and energy conversion in leaves of fig cuttings under high temperature condition, thus the heat tolerance is improved. [Conclusions] 5-ALA can be used in fig cutting propagation, which can improve young plant capacity against high temperature in the summer, and increase cutting survival and plant quality. [ABSTRACT FROM AUTHOR]