Effect of priming with gibberellic acid on acorn germination and growth of plants of Quercus robur and Q. rubra (Fagaceae)

Abstract

The effect of pre-sowing priming with gibberellic acid (GA3) solution (50 mg/L) on acorn germination and growth characteristics of 47-day-old plants of Quercus robur and Q. rubra was studied under laboratory conditions. The priming effect varied depending on the oak species and development phase of the plants. After priming, 86% of Q. robur acorns germinated that exceeded the control by 25%, while the number of sprouted acorns of Q. rubra was at the control level and amounted to 85%. The 47-day-old plants of Q. robur were divided into three groups: (1) sprouted acorns with cracked pericarp and main root; (2) seedlings with formed epicotyl and apical bud; (3) seedlings with unopened true leaves of juvenile type. The plants of Q. rubra were divided into two groups: (1) seedlings with formed epicotyl and apical bud; (2) seedlings with open true leaves. In plants of Q. robur, priming caused decrease of biomass in cotyledons, while no visible changes were found for those of Q. rubra. An increase in growth characteristics, fresh and dry biomass accumulation was noted for all Q. robur plants whereas thickening of shoots was observed only in seedlings of the second group. Instead, hormone treatment of acorns of Q. rubra led to inhibition of growth processes in plants of both groups. In general, priming with GA3 solution enhanced germination of acorns and stimulated growth of Q. robur plants and, conversely, slowed the growth of Q. rubra plants. Exogenous GA3 did not eliminate the syndrome of unfriendly seedlings of the studied oak species, but improved the viability of acorns and increased the number of seedlings/shoots.