Nitrate uptake and assimilation efficiency of excised leaves of barely (C3) and maize (C4) plants. I) effect of temperature on nitrate uptake and assimilation

Abstract

Nutrient assimilation by seedling is an early indicator of subsequent plant growth and development. This study was conducted to compare the effect of temperature on NO3 uptake and reduction by excised leaves of Barley (C3) and Maize (C4) plants with and without source of energy supply. The seedling Barley ( Hordeum Vulgare L.CV UC 337) and Maize ( Zea Mays L.CV pioneer 3162 ) were sown in vermiculate in pots kepts in growth chamber at 25°C. The tip 10 cm portion of leaves excised and placed in small glass vials containing 8 ml from,3.0,6.0 and10 mM of KNO3 solution with and without sucrose. The temperature treatments were 15,20,25,30 and 35°C. Net NO3 uptake were determined by following it`s depletion from uptake solution that initially contained the same concentration of NO3 as the induction solution. NO3 uptake by both C4 and C3 leaves was increased as NO3 level and temperature increased. While C3 leaves(Barley) was more efficient than C4 leaves ( Maize) in NO3 uptake at all NO3 concentration for NO3 reduction percent (assimilation),C4 (Maize) leaves were efficience than C3 (Barley) plants, and NO3 reduction percent increase with increasing the temperature until 25°C then decreased. The addition of sucrose by 1% to the medium as energy source increased the NO3 reduction percent in both C3 and C4 leaves.