Wheat constitutes pivotal position for ensuring food and nutritional security; however, rapidly rising soil and water salinity pose a serious threat to its production globally. Salinity stress negatively affects the growth and development of wheat leading to diminished grain yield and quality. Wheat plants utilize a range of physiological biochemical and molecular mechanisms to adapt under salinity stress at the cell, tissue as well as whole plant levels to optimize the growth, and yield by off-setting the adverse effects of saline environment. Recently, various adaptation and management strategies have been developed to reduce the deleterious effects of salinity stress to maximize the production and nutritional quality of wheat. This review emphasizes and synthesizes the deleterious effects of salinity stress on wheat yield and quality along with highlighting the adaptation and mitigation strategies for sustainable wheat production to ensure food security of skyrocketing population under changing climate.

Plant growth regulators are naturally biosynthesized chemicals in plants that influence physiological processes. Their synthetic analogous trigger numerous biochemical and physiological processes involved in the growth and development of plants. Nowadays, due to changing climatic scenario, numerous biotic and abiotic stresses hamper seed germination, seedling growth, and plant development leading to a decline in biological and economic yields. However, plant growth regulators (PGRs) can potentially play a fundamental role in regulating plant responses to various abiotic stresses and hence, contribute to plant adaptation under adverse environments. The major effects of abiotic stresses are growth and yield disturbance, and both these effects are directly overseen by the PGRs. Different types of PGRs such as abscisic acid (ABA), salicylic acid (SA), ethylene (ET), and jasmonates (JAs) are connected to boosting the response of plants to multiple stresses. In contrast, PGRs including cytokinins (CKs), gibberellins (GAs), auxin, and relatively novel PGRs such as strigolactones (SLs), and brassinosteroids (BRs) are involved in plant growth and development under normal and stressful environmental conditions. Besides, polyamines and nitric oxide (NO), although not considered as phytohormones, have been included in the current review due to their involvement in the regulation of several plant processes and stress responses. These PGRs are crucial for regulating stress adaptation through the modulates physiological, biochemical, and molecular processes and activation of the defense system, upregulating of transcript levels, transcription factors, metabolism genes, and stress proteins at cellular levels. The current review presents an acumen of the recent progress made on different PGRs to improve plant tolerance to abiotic stress such as heat, drought, salinity, and flood. Moreover, it highlights the research gaps on underlying mechanisms of PGRs biosynthesis under stressed conditions and their potential roles in imparting tolerance against adverse effects of suboptimal growth conditions.

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Zinc (Zn) deficiency can severely inhibit plant growth, yield, and enzymatic activities. Zn plays a vital role in various enzymatic activities in plants. Arbuscular mycorrhizal fungi (AMF) play a crucial role in improving the plant’s Zn nutrition and mitigating Zn stress effects on plants. The current study was conducted to compare the response of inoculated and non-inoculated maize (YH 1898) in the presence of different levels of zinc under greenhouse conditions under a Zn deficient condition. There were two mycorrhizal levels (i.e., M + with mycorrhizae, M- without mycorrhizae) and five Zn levels (i.e., 0, 1.5, 3, 6, and 12 mg kg-1), with three replicates following completely randomized design. At the vegetative stage (before tillering), biochemical, physiological, and agronomic attributes were measured. The results showed that maize plants previously inoculated with AMF had higher gaseous exchange traits, i.e., a higher stomatal conductance rate, favoring an increased photosynthetic rate. Improvement in antioxidant enzyme activity was also observed in inoculated compared to non-inoculated maize plants. Moreover, AMF inoculation also played a beneficial role in nutrients availability and its uptake by plants. Higher Zn12 (12 mg Zn kg-1 soil) treatment accumulated a higher Zn concentration in soil, root, and shoot in AMF-inoculated than in non-inoculated maize plants. These results are consistent with mycorrhizal symbiosis beneficial role for maize physiological functioning in Zn deficient soil conditions. Additionally, AMF inoculation mitigated the stress conditions and assisted nutrient uptake by maize.

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HighlightsAPSIM and CERES-Wheat were calibrated and evaluated for winter wheat in the Guanzhong Plain, China.Both models performed well as the result of the calibration based on comprehensive field data.CERES-Wheat showed high sensitivity to field capacity.APSIM showed high sensitivity to nitrate at sowing.A crop model ensemble is better than a single model application, particularly for grain yield.Abstract. Cropping system models are useful tools to estimate the impact of climate and environment on agricultural production and to improve the management of agricultural systems. Numerous crop models are used worldwide to simulate wheat crop growth and predict yield. In this study, two process-based crop models (APSIM and CERES-Wheat) were assessed for simulating wheat crop growth in the Guanzhong Plain, China. The main objectives were to compare the performance of both models and perform sensitivity analysis. The possibility of reducing the model output uncertainty by estimating ensemble means was also explored. Crop models were calibrated and evaluated using local experimental data from three growing seasons (2009 to 2012), which encompassed 27 crop managements based on different levels of irrigation and nitrogen application. APSIM and CERES-Wheat performed well after calibration. The nRMSE for aboveground biomass, grain yield, LAI, canopy nitrogen, cumulative evapotranspiration, water use efficiency, and nitrogen fertilizer productivity was less than 21%. Sensitivity analysis of both models showed that grain yield in CERES-Wheat was more sensitive to field capacity. In APSIM, grain yield was sensitive to nitrogen application rate. Mean ensemble model results showed reduced uncertainty for simulated crop parameters, especially for differences between observed and simulated grain yield, which were reduced by up to 4.1%. Overall, the results suggest that APSIM and CERES-Wheat are both suitable for simulating wheat crop growth, development, and yield in the Guanzhong Plain. Furthermore, by using the ensemble modeling approach, decision-makers can be more confident in their planning, as the information will be based on multiple models’ results. Keywords: Crop model ensemble, Model calibration, Multiple crop models, Sensitivity analysis, Winter wheat.