Supra‐optimal growth temperature exacerbates adverse effects of low Zn supply in wheat

Abstract

Rising temperatures are a major threat to global wheat production, particularly when accompanied by other abiotic stressors such as mineral nutrient deficiencies. This study aimed to quantify the effects of supra‐optimal temperature on growth, photosynthetic performance, and antioxidative responses in bread wheat cultivars grown under varied zinc (Zn) supply. Two bread wheat cultivars (Triticum aestivum L., cvs. Lasani‐2008 and Faisalabad‐2008) with varied responsiveness to Zn supply and drought tolerance were cultured in nutrient solution with low (0.1 µM) or adequate (1.0 µM) Zn under optimal (25/20°C day/night) or supra‐optimal (36/28°C day/night) temperature regimes. Supra‐optimal temperature severely reduced root but not shoot biomass, whereas low Zn reduced shoot as well as root biomass. Shoot‐to‐root biomass ratio was reduced under low Zn but increased under supra‐optimal temperature. Supra‐optimal temperature inhibited root elongation and volume particularly in plants supplied with low Zn. In both cultivars, Zn efficiency index was reduced by supra‐optimal temperature, whereas heat tolerance index was reduced by low Zn supply. Supra‐optimal temperature decreased photosynthesis, quantum yield, and chlorophyll density in low‐Zn but not in adequate‐Zn plants. In comparison, low Zn decreased specific activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) and increased glutathione reductase (GR), where supra‐optimal temperature increased SOD, decreased GR and did not change APX activity in leaves and roots. Moreover, supra‐optimal temperature severely reduced shoot Zn concentration and Zn uptake per plant specifically under adequate Zn supply. Overall, supra‐optimal temperature exacerbated adverse effects of low Zn supply, resulting in severe reductions in growth traits viz. shoot and root biomass, root length and volume, and consequently impeded Zn uptake, enhanced oxidative stress and impaired photosynthetic performance. Adequate Zn nutrition is crucial to prevent yield loss in wheat cultivated under supra‐optimal temperatures.

Response of Phenylpropanoid Pathway and the Role of Polyphenols in Plants under Abiotic Stress

“…Increased ROS generation under abiotic stresses enhanced itself exponentially the production of ROS [62], which result in peroxidation and destabilization of cellular membranes. Recently Rehman, et al [63] observed that heat stress and Zn deficiency cause reductions in growth (shoot and root biomass, and root length), and consequently impeded nutrient uptake, enhanced lipid peroxidation and impaired photosynthetic performance. In plants, ROS is produced from 1–2% of total O 2 consumed in high active cell organelles like chloroplasts, mitochondria, and peroxisomes (Figure 1; [64]).…”

Common Bean Yield and Zinc Use Efficiency in Association with Diazotrophic Bacteria Co-Inoculations

“…Zinc soil application is one the most adaptable strategies to boost Zn assimilation in plant tissues and grains [26] in Zn deficient soil ranging from 0.0 to 0.3 mg dm 3 [46]. In addition, Zn agronomic application improves different physiological functions and results in better growth, Zn use efficiency, and high productivity [20,22,26]. The positive Pearson's correlation between Zn uptake (Zn concentration in soil and tissues and Zn accumulated in aerial part) and Zn efficiencies with common bean shoot dry matter and grain yield support this hypothesis (Figure 5).…”

Zinc–nitrogen interaction effect on wheat biofortification and nutrient use efficiency

“…In our study, the use of natural organic Zn fertilizers enhanced the chlorophyll a content more than the inorganic Zn fertilizer. The latter affected photosynthesis and also resulted in higher biomass and grain yields (Alloway, 2008;Rehman et al, 2019) (see Tabs. S3 and 2).…”