Low irrigation water minimizes the nitrate nitrogen losses without compromising the soil fertility, enzymatic activities and maize growth
Ihsan Muhammad, Ju Zhi Lv, Li Yang, Shakeel Ahmad, Saqib Farooq, Muhammad Zeeshan, Xun Bo Zhou
Abstract
Abstract Nitrate nitrogen (NO 3 −_ N) leaching increased with nitrogen (N) fertilization under high water supply to the field negatively affected the maize growth and performance. This study aimed to understand the mechanisms of NO 3 −_ N leaching on a biochemical basis and its relationship with plant performance with 5 different doses (0, 200, 250, 300, 350 kg N ha − 1 ) of N fertilizers under low (60%; LW) and high (80%; HW) water holding capacity. Soil and plant enzymes were observed at different growth stages (V9, R1, R3, and R6) of the maize, whereas the leachates were collected at 10-days intervals from the sowing date. The LW had 10.15% lower NO 3 −_ N leachate than HW, with correspondence increases in grain yield (25.57%), shoot (17.57%) and root (28.67%) dry matter. Irrespective of the irrigation water, RubisCo, glutamine synthase (GS), nitrate reductase (NR), nitrite reductase (NiR), and glutamate synthase (GOGAT) activities increased with increasing N fertilizer up to the V9 growth stage and decreased with approaching the maturity stage (R6) in maize. In HW irrigation, soil total N, GOGAT, soil nitrate (NO 3 −_ N), leached nitrate (LNO 3 −_ N), root N (RN), leaf N (LN) were positively correlated with N factors suggesting the higher losses of N through leaching (11.3%) compared to LW irrigation. However, the malondialdehyde (MDA), hydrogen peroxide (H 2 O 2 ), superoxide (O 2 − ), and proline were negatively correlated with the other enzymatic activities both under LW and HW irrigation. Thus, minimizing the NO 3 −_ N leaching is possibly correlated with the LW and N300 combination without compromising the yield benefit and improving enzyme activities.