High Nitrogen Enhance Drought Tolerance in Cotton through Antioxidant Enzymatic Activities, Nitrogen Metabolism and Osmotic Adjustment

Abstract

Drought is one of the most important abiotic stresses and hampers many plant physiological processes under suboptimal nitrogen (N) concentration. Seedling tolerance to drought stress is very important for optimum growth and development, however, the enhancement of plant stress tolerance through N application in cotton is not fully understood. Therefore, this study investigates the role of high N concentration in enhancing drought stress tolerance in cotton. A hydroponic experiment supplying low (0.25 mM) and high (5 mM) N concentrations, followed by 150 g L−1 polyethylene glycol (PEG)-induced stress was conducted in a growth chamber. PEG-induced drought stress inhibited seedling growth, led to oxidative stress from excessive malondialdehyde (MDA) generation, and reduced N metabolism. High N concentrations alleviated oxidative damage and stomatal limitation by increasing antioxidant enzymatic activities, leaf relative water content, and photosynthesis in cotton seedlings under drought stress. The results revealed that the ameliorative effects of high N concentration may be ascribed to the enhancement of N metabolizing enzymes and an increase in the amounts of osmoprotectants like free amino acids and total soluble protein. The present data suggest that relatively high N concentrations may contribute to drought stress tolerance in cotton through N metabolism, antioxidant capacity, and osmotic adjustment.

Species responses to changing precipitation depend on trait plasticity rather than trait means and intraspecific variation

“…This seems to be opposite to the above pattern that resource‐acquisitive species are more responsive to precipitation. However, several recent studies also suggest that high nitrogen favours plant tolerance under drought stress (Iqbal et al., 2020; Weih, Bonosi, Ghelardini, & Rönnberg‐Wästljung, 2011), which potentially reduces plant responses to precipitation. Further studies are still necessary to test this debate.…”

Variations in Nitrogen Metabolism are Closely Linked with Nitrogen Uptake and Utilization Efficiency in Cotton Genotypes under Various Nitrogen Supplies

“…For the determination of total free amino acids, the ninhydrin method was used as previously described [88] with some modifications [89]. Extraction buffer composed of acetic acid/sodium acetate (pH 5.4) and the final values of free amino acids were detected at 580 nm by using a spectrophotometer (UV-2600) (722N, Shanghai Metash Instrument Co., Shanghai, China).…”

Drought, Salinity, and Low Nitrogen Differentially Affect the Growth and Nitrogen Metabolism of Sophora japonica (L.) in a Semi-Hydroponic Phenotyping Platform

“…It is worth noting that although some effects are shared between salinity and drought stress, as both stresses lower the soil water potential, differences in the potential regulatory mechanisms exist, which eventually affect N absorption, reduction, and assimilation differently. Generally, drought reduces N uptake and translocation, as well as NR and GS activities, because of restricted photosynthetic and transpiration rates ( Bowen et al, 2018 ; Iqbal et al, 2020 ). Apart from the results caused by limited water absorption, salt stress adds additional negative effects.…”