DETERMINATION OF OPTIMUM CONCENTRATION AND TIME PRIMING OF STEVIA SEED WITH BORIC ACID (H3BO3) MICRONUTRIENT

Abstract

In order to determine anoptimal duration and concentration of priming of stevia seed with boric acid for improvinggermination, an experimental factorial completely randomized design with three replications was conducted inthe laboratory of Seed Science and Technology, Shahed University of Tehran in 2015. The first factor was differentconcentrations of boric acid (zero, 0.5, 1, 1.5 and 2 percent) and the second factor of priming time (0, 8, 16, 24 and 32hours). Effects of concentration and duration of priming with Boric acid was significant on germination percentage,germination mean time, germination rate, germination energy, germination uniformity, germination mean daily,germination daily rate, germination value, seedling length and seed vigor index. The highest germination percentage,germination rate, germination energy, germination mean daily germination value and seed vigor index was 24 hourspriming and the highest germination percentage, germination rate, germination potential, germination value and seedvigor index in priming of 2% Boric acid were obtained. Germination uniformity highest in 24 hours at 1% concentrationpriming of boric acid (5.51). Seedling length in 24 hours at 1.5% concentration priming with boric acid washighest average 1.02 cm. Generally Stevia seed priming with boric acid for 24 hours at concentrations of 1.5 to 2percent had positive effects on germination indexes and seedling growth.