NATURAL ABUNDANCES OF¹⁵NITROGEN AND¹³CARBON INDICATIVE OF GROWTH AND N₂FIXATION IN POTASSIUM FED LENTIL GROWN UNDER WATER STRESS

Abstract

Dual natural abundance analysis of 15Nitrogen (N) and 13Carbon (C) isotopes in lentil plants subjected to different soil moisture levels and rates of potassium (K) fertilizer were determined to assess crop performance variability in terms of growth and N2-fixation (Ndfa). The δ15N values in lentils ranged from +0.67 to +1.36‰; whereas, those of the N2-fixed and reference plant were −0.45 and +2.94‰, respectively. Consequently, the Ndfa% ranged from 45 and 65% of total plant N uptake. Water stress reduced Δ13C values. However, K fertilization enhanced whole plant Δ13C along with dry matter yield and N2-fixation. The water stressed plants amended with K fertilizer seemed to be the best treatment because of its highest pod yield, high N balance, and N2-fixation with low consumption of irrigation water. This illustrates the ecological and economical importance of K fertilizer in alleviating water stress occurring during the post-flowering period of lentil.