Abstract:

A hydroponics experiment was used to study the effects of alginate derived oligosaccharides on photosynthetic characteristics and carbon metabolism of Brassica campestris L. ssp. chinensis var. utilis Tsen et Lee. After adding alginate derived oligosaccharides, the net photosynthetic rate (Pn), water use efficiency (WUE) and CO2 carboxylation efficiency (CE) in leaves were improved; an increased light saturation point (LSP) and a decreased light compensation point (LCP) were observed. The minimal fluorescence (Fo), the maximal fluorescence (Fm), the variable fluorescence (Fv), photosystem II maximal photochemical efficiency (Fv/Fm) and its electron transfer rate (ETR) and the non-photochemical quench (NPQ) to some extent was improved. Meanwhile the activity of sucrose phosphate synthase (SPS) and sucrose synthase (SS) increased evidently which facilitated the increase of sucrose contents. In early stage of study, invertase activity also increased significantly, while they decreased significantly at the 6th day; glucose contents also decreased. The starch contents were gradually increased with time, but cellulose contents were contrary. The results suggested the application of alginate derived oligosaccharides could promote the trapping and conversion of light energy in B. campestris L. ssp. chinensis var. utilis Tsen et Lee, enhance light utilized efficiency, change the process of the carbon metabolism and facilitate the accumulation of carbon metabolism products.