EFFECT OF PLANTING DATE, SPARYING WITH KINETIN ON VITALITY AND VIGOUR OF SEEDS OF STEVIA REBAUDIANA BERTONI

Abstract

             A laboratory experiment was carried out in the Seed Technology Laboratory of the Field Crops Department - College of Agricultural Engineering Sciences - University of Baghdad- Al-Jadriyah, aiming to study the effect of planting dates and spraying with kinetin and the interaction between them on the vitality and vigor parameters of the resulting (stevia rebaudina) plant seeds. The experiment was implemented according to the completely randomized design (CRD) with three replications comprising two factors. The first factor represented the dates of planting seedlings, as it included three spring dates: February 15, March 1, and March 15,. The second factor was spraying with three concentrations of kinetin (25, 50, and 75mg L^-1), in addition to the control treatment of spraying with distilled water only, referred to as K₀.​ The results showed that the late planting date was superior in the first count and the second count in the standard laboratory germination test, radical length, plumule length, seedling dry weight, cold test, and seedling vigor index (21.50%, 55.56%, 15.936 mm, 8.719 mm, 3.494 mg, 24.23%, 1374.0 mg, respectively). The highest concentration of kinetin in the first count and the second count was superior in the standard laboratory germination test, radical length, plumule length, seedling dry weight, cold test, and the seedling vigor index (20.00%, 49.58%, 14.998 mm, 7.745 mm, 2.758 mg, 20%, 1170.5 mg, respectively). Based on the findings of this study, altering the planting date and using kinetin spray significantly impacts the viability of the resulting seeds. Delaying the planting date until mid-March and using the highest concentration of kinetin (75 mg L^-1) has been observed to increase the seed viability.