Examining Nicotinamide Application Methods in Alleviating Lead-Induced Stress in Spring Barley

Abstract

Cereals are a staple food in many regions of the world and are essential for global food security. Lead is one of the most significant environmental stressors, impacting plants throughout their life cycle and causing substantial damage to plant growth and development. It disrupts intracellular processes, thereby reducing plant productivity. The aim of this study was to determine the effect of exogenously applied vitamin PP (100 µM) (nicotinamide) on the morphological, physiological, and biochemical parameters of spring barley var. Eunova under lead stress (1 mM Pb(NO3)2) and to determine the most effective method of applying this vitamin in a pot experiment. Vitamin PP was applied exogenously through three different methods: seed soaking, foliar application, and soil irrigation. The application of 1 mM Pb(NO3)2 resulted in decreased root (from 13.9% to 19.9%) and shoot length (from 16.2% to 24.8%) and increased catalase (CAT) activity from 45% to 106%, and peroxidase (POX) activity from 39% to 46% compared to the control. Lead stress led to an increase in proline (Pro) content from 30 to 63% and comparatively in malondialdehyde (MDA) content (rising from 61% to 79.4%), as well as elevated assimilatory pigment content (by 35%) in barley grown in the pot experiment. Exogenous vitamin PP significantly and positively influenced the improvement of the measured morphological, biochemical, and physiological parameters, reducing the toxicity of lead salts. It was shown that the most effective method of vitamin PP application was achieved through foliar spraying and irrigation.