Potassium Supply Influences Molybdenum, Nitrate, and Nitrate Reductase Activity in Eggplant

Abstract

Greenhouse experiments were conducted for two years (1993–1994) with eggplants to study the impact of potassium (K) as K₂SO₄ (0.5 mM, 1 mM, 2 mM, and 3 mM) on molybdenum (Mo) distribution and on aspects of nitrate (NO₃ ⁻) metabolism, and fruit quality. The nitrates and Mo in leaf blades, petioles, and fruits as well as foliar in vivo nitrate reductase (NR; E.C. 1.6.6.1) activity were analyzed. In view of these results, the K application at levels exceeding 0.5 mM K, altered the NO₃ ⁻ and Mo status and distribution in the aboveground organs of eggplant. The 3 mM K distributed the NO₃ ⁻ proportionally between leaf blades, petioles, and fruits. The 0.5 mM K and the 1 mM K increased the NO₃ ⁻ and Mo concentration in fruits, respectively. These results indicated the 3 mM K the most appropriate treatment for the greenhouse eggplant production under Mediterranean climate conditions, with reduced NO₃ ⁻ density in fruits for human consumption.

Keywords:

• Fruit
• Leaf
• Nitrogen
• Solanum melongena

Acknowledgments