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

Influence of salt stress on photosynthesis in modern rice varieties (Oryza sativa). Claudio Cerboncini^*,1, Phap Vu Anh², Andreas Brandt¹, Jens Krause¹, Anette Friebe¹, Heide Schnabl^{1, 3}, ¹ center of advanced european studies and research, Bonn, Germany² College of Agriculture, Cantho City, Cantho Province, Vietnam³ Institute of Molecular Physiology and Biotechnology of Plants, Bonn, Germany

ABSTRACT- Rice is the worlds most important food crop and a primary source of food for more than half of the worlds population. A series of stresses such as drought, excess water, mineral deficiencies and toxicities in soil and unfavorable temperatures affect rice productivity. The progress in developing crop cultivars for tolerance to abiotic stresses has been slow because of lack of knowledge of the mechanisms of tolerance, poor understanding of inheritance of resistance or tolerance and lack of efficient and early techniques for screening the germplasm and breeding materials. Nevertheless, rice cultivars with varying degrees of tolerance to abiotic stresses have been developed. Therefore, we investigated the influence of different salt concentrations (NaCl) on photosynthesis in order to evaluate early physiological markers of plant stress physiology in controlled environment and under greenhouse conditions. Effects have been compared for two modern rice varieties, IR 64 and MTL 119, differing remarkably in their salt-tolerance. A new pulse amplitude modulation imaging device (Walz) was used for the experimental investigation of the photosynthetic yield and quenching. This modern imaging- PAM is particulary well suited for the study of leave heterogeneities in photosynthetic activity. Using this powerful technique it seems to be possible to use photosynthetic parameters as sensitive and early physiological markers for abiotic stress in rice. First results of studies of the influence of brassinosteroid phytohormones on salt tolerance of the rice plants will be presented here.

KEY WORDS: salt stress, osmotic stress, Oryza sativa, salt tolerance