Nano-nitrogen fertilization and biostimulant application improve barley growth and productivity under saline irrigation

Abstract

Soil and irrigation water salinity are major constraints to agricultural productivity, especially in regions that rely on groundwater irrigation. This study evaluated the effectiveness of nano-nitrogen fertilizer and the Biohealth biostimulant in mitigating salt stress and improving barley growth and productivity under saline irrigation. A factorial experiment arranged in a randomized complete block design (RCBD) was conducted at the College of Agriculture, University of Samarra, during the 2024-2025 growing season. Four fertilization treatments were tested: conventional chemical fertilization (T1), nano-nitrogen fertilizer (T2), Biohealth biostimulant (T3), and combined nano-nitrogen + Biohealth application (T4), under three irrigation-water salinity levels: 0.8 (S1), 4.2 (S2), and 6.3 dS/m (S3). Increasing salinity significantly reduced plant height, flag leaf area, number of grains per spike, 1000-grain weight, grain yield per plant, total chlorophyll content, and salt tolerance index. Conversely, nano-nitrogen and Biohealth improved most growth, physiological, and yield traits, particularly when applied together. Under non-saline irrigation (S1), T4 recorded the highest plant height (62.33 cm), flag leaf area (28.75 cm2), number of grains per spike (45.34), 1000-grain weight (45.66 g), grain yield (4.03 g per plant), and total chlorophyll content (3.62 mg/g FW). The highest proline content (3.73 µg/g FW) occurred under severe salinity (S3) in the conventional fertilization treatment, whereas the highest salt tolerance index (69.22%) was recorded under moderate salinity (S2) with T4. These findings indicate that the combined use of nano-nitrogen and Biohealth may be an effective strategy for mitigating the adverse effects of saline irrigation and improving barley performance in arid and semi-arid environments.