'On-farm' seed priming with Zn plus Mn is an effective way to improve germination and yield of marigold

One of the major crop productivity constraints in the world is the unavailability of crop nutrients in appropriate amount and form to crops. In order to study the effect of seed priming with zinc and manganese on germination and essence of marigold in laboratory and field seed priming experiments were done at the Research Station of Islamic Azad University, Tabriz, Iran, with marigold (Calendula officinalis L.), using solutions at four concentrations of zinc and manganese. The priming solution concentrations were 0.5, 1, 1.5 and 2% Zn or Mn, that is, 14.5, 29, 43.5 and 58 g Zn L-1 or 19, 38.5, 58 and 77 g Mn L-1, respectively. Each treatment involved weighing approximately 10 g of the seed in a plastic cup, adding 20 mL of the priming solution, and allowing the seed/solution mixture to sit covered with plastic for 12 h. The essential oil from marigold flowers was isolated by hydro distillation using Clevenger's apparatus. All data was statistically analyzed using MSTAT-C software. Results showed that priming at the concentrations of 1%, 1.5% Zn, 1% Mn, or 1% Zn+1.5% Mn increased germination rate of marigold seeds compared to an unprimed control. It is revealed that seed priming with ZnSO4 and MnSO4 may give better results on seedling vigor index of marigold. The highest yield was obtained from seed soaking treatments in 1% Zn+1.5% Mn, 1.5% Zn, 1% and 1.5% Mn solutions. When seeds primed in the highest concentration of Mn, marigold statistically produced flower yield similar to unprimed treatment. Flower essential oil yield among treatments ranged from 0.12 to 0.27mL per 100 g dry weight in 0.5% Mn and 1% Zn+1.5% Mn solutions, respectively. All the seed treatments gave a significant increase in essential oil yield over control. The data from this study confirm that simple 'on-farm' seed priming with Zn+Mn is an effective way to improve germination and yield of marigold.