Effects of exogenous phenolic acids on growth and photosynthesis characteristics of mulberry seedlings

In order to investigate the effect of phenolic acids in soybean root exudate on the growth of mulberry, effects of 3Nitrophthalic acid, 2Methoxybenzoic acid on growth and photosynthesis characteristics of one year Qinglong mulberry seedlings were studied. The results showed that the effects were different among two exogenous phenolic acids. When the concentration of exogenous 3Nitrophthalic acid was lower than 10-5 molL-1, the content of chlorophyll of mulberry leaves, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular CO2 (Ci) and assimilate accumulation increased with the increasing of the concentrations of 3Nitrophthalic acid, which promoted the growth of plant height, root length and biomass. When the concentration of exogenous 3Nitrophthalic acid was higher than 10-2 molL-1, the content of chlorophyll of mulberry leaves, Pn, Ci and ETR, ФPSⅡ were decreased significantly, the plant height, root length, leaf number and biomass of mulberry were also decreased. The content of chlorophyll of mulberry leaves, Gs, Tr, Pn, ФPSⅡ, ETR and photochemical quenching (qP) and the rate of energy dissipation were increased with the increasing of the concentrations of exogenous 2Methoxybenzoic acid. The study indicated that 3Nitrophthalic acid had dual effects on growth and photosynthesis characteristics of mulberry seedlings, low concentrations of 3Nitrophthalic acid may stimulate and high concentrations may inhibit growth of mulberry seedlings. 2Methoxybenzoic acid had adverse effects on the leaf photosynthetic system of mulberry seedlings