Effect of Brassinolide Soaking Treatment on Growth of Vallisneria natans.

In aquatic ecological restoration projects, V. natans (Vallisneria natans (Lour.) Hara), a species of submergent plant, after being transplanted often experiences a poor growing condition and a lengthy adaption period, however, brassinolides possess considerable effectiveness of plant development and metabolism according to available research reports. In an attempt to employ a phytohormone soaking pre-treatment method to study the effect of brassinolides' effect on V. natans development, a laboratory experiment was conducted probing into the influencing factors: brassinolides dosage (0, 0.25, 0.5, 1, 2 and 4 mg/L) and soaking time (10, 20, and 40 minutes). The results showed that the pre-treatment with brassinolide facilitated the improvement to some extent of biomass, plant height, number of leaves, number of tillers, and chlorophyll of V. natans, and that the effect of soaking solution concentration was more pronounced than immersion time; it appeared that under the condition of above three soaking intervals the biomass of V. natans increased to the maximum at the solution concentration of 0.5 mg/L; however, 10 min soaking time gave rise to biggst boosting effect, and from the perspective of plant height indicator, as the soaking time was 10 min brassinolide of 0.25-2 mg/L concentration had a notable positive effect on the plant height of V. natans (P<0.05). In terms of chlorophyll indicators, it was the best condition that the content of chlorophyll a and chlorophyll b of V. natans was boosted when brassinolide concentration ranged 0.5-1 mg/L and soaking time was 10 min. In accordance with the experimental data obtained and considering economic cost and time cost, it is recommended that prior to the transplantation V. natans be soaked with brassinolide at a concentration of 0.5 mg/L for 10 min, in this way the problem of V. natans colonizationcan could be successfully solved. Finally, it is expected that the experimental results could provide theoretical references for the quick recovery of submerged macrophytes in aquatic environment. [ABSTRACT FROM AUTHOR]