PARENT SESSION
Posters P6D Crop photosynthesis, agricultural biotechnology. Abstracts (742-753)

Photosynthesis of soybean at different leaf development stages treated with lipo-chitooligosaccharides. Juan Almaraz^*,1, Xiaomin Zhou¹, Donald Smith¹, ¹ Department of Plant Science, Ste. Anne de Bellevue, Quebec, Canada

ABSTRACT- Lipo-chitooligosaccharides (LCOs), also known as Nod factors, are compounds produced by rhizobia in the first steps of the legume root hair infection. They induced a series of responses in the host plant that leads to the nodule formation. Recently it has been demonstrated by our lab that LCOs can stimulate other physiological processes such as seed germination, plant growth, and photosynthesis. Our objective was to evaluate the effect of four LCOs on soybean photosynthesis over a range of leaf development stages. Experiments were conducted under greenhouse conditions. One group of soybean plants, at the second trifoliate leaf stage, was sprayed with four submolar concentrations of LCOs, and another group was sprayed with four types of LCO at one concentration, in both experiments photosynthesis was evaluated on the second fully expended trifoliate leaf. A third group of soybean plants was sprayed with one LCO at one concentration, and photosynthesis was evaluated on two leaves, the second fully expended leaf and the third leaf, during expansion. Similar experiments were established using plants at the primary leaf stage. Dry weight was measured after three weeks. But in the last one leaf area and chlorophyll also were included. Photosynthesis was increased by two LCOs. The response to LCOs increased when the concentration of LCO was increased. The maximum increase in photosynthesis due to the effect of LCO was around 10.5%. Young trifoliate leaves responded better to LCO than mature ones; this was also the case with primary leaves. Higher concentrations of LCO also had positive effects on total plant dry weight.

KEY WORDS: Lipo-chitooligosaccharides, Soybean, Photosynthesis