DETERMINING THE ZINC REQUIREMENT OF ONION BY SEED ANALYSIS

Abstract

Our study analyzed the effect of foliar tissues and seed tissue for determining the micronutrient status of a crop. Zinc (Zn) requirements of onion (Allium cepa L.) leaves and seeds were estimated from yield response curves based on field experiment conducted on a Zn-deficient calcareous soil. Three onion cultivars, i.e., ‘Swat-1’, ‘Phulkara’, and ‘Sariab Red’ were grown by applying 0, 2, 4, 8, and 16 kg Zn ha⁻¹. Zinc application significantly increased seed yield of all the three cultivars of onion. The order of seed yield response to Zn fertilization was: ‘Swat-1’ < ‘Phulkara’ < ‘Sariab Red’. Fertilizer Zn requirement for near-maximum seed yield was 2 kg Zn ha⁻¹. Zinc concentration in mature onion seed also appeared to be a good indicator of soil Zn availability status. Critical Zn concentration in seed was 18 mg Zn kg⁻¹, and in matured leaves was 21 mg kg⁻¹.

Keywords:

• Allium cepa L.
• atomic absorption spectrophotometry
• calcareous soils
• micronutrient requirement
• plant analysis