POLLEN QUALITY AND TESTS

The pollen grain is an organism which is emitted at anthesis in a more or less dehydrated state. This mechanism corresponds to an adaptative strategy developped by biological system in order to ensure their dissemination. However, pollen which high water content at anthesis (more than 40% of the fresh weight) are pollen sensitive to the dehydration which occurs after the anther dehiscence. Changes in vegetative plasma membrane have been studied by a multidisciplinary approach during dehydration. This study has been conducted simultaneously on different aliquot parts of the same pollen population using cytological tests (fluorochromatic tests, freeze-fracture), physiological test (in vitro germination, seed set) and proton nuclear magnetic resonance. We have been able to correlate pollen dehydration and the ultrastructural changes in pollen envelope, and then, we have determined quantity of vital water in stress sensitive pollen.