Effect of Zinc Seed Priming on Fertilizer Depot Exploitation in Oil Seed Rape.

Oilseed rape has a long tap root system to acquire more nutrients. Due to its non-mycorrhizal nature, it has a high dependency on fine and longer roots. Zinc (Zn) nutrition helps improving root length and tolerance against low temperature stress. This study was conducted to determine the potential of Zn seed priming in improving the nutrients depot exploration through better root growth in two oil seed rape (Brassica napus L.). Seeds of two oil seed rape cultivars Avatar and Trapper were primed with Zinc sulphate (ZnSO₄.7H₂O) as 25µM, 50µM and 75µM for 24 h duration while ammonium phosphate (NH4)₃PO₄ was used as depot at 8 cm under the seed. Seeds were sown in a rhizobox placed in green house. Rhizobox with cultivars Avatar and Trapper at had ambient and 12°C root zone temperatures, respectively. Seed priming with Zn significantly increased the seed Zn contents by 284% in cv. Avatar and 141% in cv. Trapper. Higher root biomass, fine root length and root length were observed in the depot zone than the corresponding soil compartment under broadcast fertilization and this effect was particularly expressed with Zn seed priming during the first three weeks of experimentation. An increase in shoot dry weight, plant height and root hair density were also noted in winter rape cv. Avatar. Spring rape cv. Trapper showed significant improvement only in plant height, and shoot dry weight at low root zone temperature. There was no influence of Zn application, through either method in both cultivars, on shoot Zn concentration. However manganese concentration was higher in broadcast treatments while reverse was true for the phosphorous. In conclusion, Zn seed priming in combination with fertilizer placement improved the root growth, root fineness, root hair length and root density, which could be beneficial for early plant establishment and growth.