Highlights Ultrasound treatment reduces the lignin intensity in cell wall. Ultrasound treatment reduced the relative hemicellulose content. Ultrasound treatment increased the crystallinity. Ultrasound-alkali treatment had more pronounced effects on cell wall.

No abstract

No abstract

To assess the response of Ottelia acuminata to a water-depth gradient, we investigated the plant growth and leaf photosynthesis by setting three water depths (0.5, 1.0, and 1.5 m) in situ in Yilong Lake, Yunnan Province, China. The results showed that the growth and photosynthetic fluorescent characteristics of O. acuminata exhibited different responses to the waterdepth gradient. The plant height, fresh weight, root length, and leaf number of O. acuminata, varied significantly with changes in the water depth. With regard to the photosynthetic fluorescent characteristics of leaves, the maximum quantum yield half-saturation light intensity and fluorescence parameter of photosystem II markedly improved with increasing water depth. The increase of photosynthetically active radiation resulted in a decreased photochemical quenching coefficient (qP). In contrast, the nonphotochemical quenching coefficient was relatively high in the leaves of O. acuminata in shallow water under high photosynthetically active radiation. The chlorophyll content of the leaves varied significantly with changes in the water depth. Higher chlorophyll a, chlorophyll b, and carotenoid contents were detected in the leaves of O. acuminata at the water depth of 1.5 m. The results of the growth and photosynthetic fluorescent characteristics of O. acuminata indicate a better protection mechanism against high light in the leaves of O. acuminata in shallow water and a higher photosynthetic efficiency, as well as a greater photosynthetic potential, in the leaves of O. acuminata in deep water.