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.
