Exogenous Pectic-Oligosaccharide Derived from Pomelo Peel Improved the Growth of Rice Seedlings

Pectic-oligosaccharides (POS), a natural biostimulant, can influence
plant development through various mechanisms. This study investigated the
impact of POS-M concentrations derived from pomelo peel on rice seed growth and carbohydrate metabolism. Rice seeds soaked in a 1,000 ppm POSM solution for 3 d before being placed in a moist plastic box for 7 d enhanced seedling root and shoot length by 6.9% and 6.2%, respectively, compared to the control. This concentration may promote rice seedling growth indirectly by stimulating carbohydrate metabolism. It can decrease residual starch content in seeds by 6% when compared to water, as well as glucose, sucrose, and maltose accumulation in remaining seeds after 7 d of sowing. While the amount of fructose and glucose in shoots increased by 47% and 26%, respectively, the amount in roots increased by 191% and 146%. The plant carbohydrate metabolism pathway was correlated to these sugar profiles. Our results suggest that POS concentration can influence rice seed growth promotion, and carbohydrate metabolism is important in plant development.