Response of Pea Plants (Pisum sativum L.) to Reduced Supply with Molybdenum and Copper

The role of molybdenum (Mo) and copper (Cu) in regulation the activities of the enzymes involved in primary nitrogen assimilation in particular the nitrate reductase (EC 1.6.6.1) and glutamine synthetase (EC 6.3.1.2) was examined. Pea plants were grown in a phytotron chamber at 12 h photoperiod, day /night temperature 25/18 C and photon flux density of 95 μmol m s until 21 day. Plants were grown at full strength Helriegel nutrient solution competed with micronutrients as in Hoagland and Arnon and reduced Mo and Cu concentrations. Although only extremely small amounts of Mo and Cu are required for normal plant growth, reduced supply with Mo and Cu to the growth medium decreased activities of the enzymes (nitrate reductase and glutamine synthetase) involved at initial steps of nitrate assimilation, fresh weight, and plastid pigment content (total chlorophyll and carotenoids). Accumulation of nitrates in plant tissues enhanced, especially in the variants with restrictive Cu concentration.