Effect of Water Stress on Germination and Reserve Carbohydrate Metabolism in Germinating Seeds of<i>Ceratonia siliqua</i>L.

Abstract

Ceratonia siliqua L. seeds were germinated in water and under a range of PEG 4000-induced moisture stresses. Germination was retarded as water stress was stronger. Axis growth, total dry weight decrease, and starch formation in the embryo were closely correlated to galactomannan depletion, the latter being inhibited with lower external water potential. Endosperm α-galactosidase was inhibited in PEG-germinated seeds, while embryo α-galactosidase activity was not significantly affected. Soluble sugar content was higher in cotyledons of seeds geminated under stress conditions, mainly due to higher sucrose accumulation. The higher sugar content in the endosperm was mainly due to higher galactose and mannose content. Water stress effected a delay in the raffinose-type oligosaccharide depletion.