Effects of exogenous 5-aminolevulinic acid on seed germination and seedling photosynthetic characteristics of Belamacanda chinensis / 中草药

ABSTRACT

Objective: To increase the resistance of Belamacanda chinensis seeds and seedlings under the salt stress Methods: We used 5-aminolevulinic acid (ALA) to treat B. chinensis seeds under salt stress (100 mmol/L NaCl). And several physiological indexes of the seeds were measured, such as the proportion of seed germination and the photosynthetic characters of the seedling. Results: The seeds had been damaged heavily by the salt stress (100 mmol/L NaCl); After being treated by ALA (25-100 mg/L), several physiological indexes of the seeds had been recovered, among which the effect of 75 mg/L ALA treatment was the most significant, and every index reached the maximum. The ALA could increase the contents of chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids significantly, and enhance the maximum fluorescence (Fm), photochemical efficiency of photosystem II (PSII, Fv/Fm), PSII photochemical efficiency (Fv'/Fm'), PSII actual photochemical efficiency (ΦPSII), photochemical quenching coefficient (qP), while decrease the levels of non-photochemical quenching (NPQ) coefficient and heat dissipation rate (HDR) significnatly. The proportion of ALA absorbed light in photochemistry (P) was obviously increased, and the fraction of antenna pigment heat dissipation (D) and excess energy (E) for NPQ indicated downtrend. Conclusion: This experiment proved that exogenous ALA could improve the seed germination rate, improve the content of seedlings photosynthetic pigment, promote the reasonable energy distribution, reduce the dissipation of excess excitation energy, improve the efficiency of photosynthetic electron transport, effectively alleviate the damage of seedling, caused by the salt stress, and improve the resistance ability of stress of plant.