Drought and heat stress reduce yield and alter carbon rhizodeposition of different wheat genotypes

Abstract

Drought and high temperature are major environmental stress factors threatening wheat production during grain filling stage resulting in substantial yield losses. Four wheat genotypes (Suntop, IAW2013, Scout and 249) were planted under two temperature levels (25 and 30°C) and two water levels (15% and 25% soil moisture content). Wheat yield, leaf δ13C, plant rhizodeposition, shoot biomass and root traits were examined. Low moisture (drought stress) and high temperature (heat stress) decreased the grain yield of all wheat genotypes, in particular 249, while combined drought and temperature stresses had the most pronounced negative effect on plant biomass and grain yield. Decreasing soil water availability decreased the allocation of plant‐derived C to soil organic carbon (SOC) and to microbial biomass through rhizodeposition. Leaf δ13C decreased with increased yield, suggesting that higher yielding genotypes were less water stressed and allocated less C to SOC and microbial biomass through rhizodeposition. Wheat genotypes with lower root/shoot ratios and thinner roots were more efficient at assimilating C to the grain, while genotypes with higher root/shoot ratios and thicker roots allocated more C belowground through rhizodeposition at the expense of producing higher yield. Therefore, improving these traits for enhanced C allocation to wheat grain under variable environmental conditions needs to be considered.

A manifold response of forage rape to combined heat wave and drought under current and elevated CO2

“…Whereas elevated concentrations of Mg and Na could lead to suppressed Ca transport and maintain its low concentration in shoots after recovery. Another reason could be decreased absorption of Ca from soil due to reduced root biomass and/or the heat‐ and drought‐induced shift in rhizodeposition, microbial biomass and in turn a reduction in nutrient availability, as was discussed by (Bakhshandeh et al., 2019). However, as the content of other elements increased or did not change, the primary cause should be disturbances in the balance of particular elements at the levels of absorption and transport in forage rape seedlings.…”

“…The yield of spring crops tends to be more seriously affected, as was estimated during the last HW in Europe in June 2019 (EC [European Commission 2019]). The effect of heat per se is species‐dependent and under optimal water availability it can be negligible or even turn into positive; however, consecutive drought significantly intensifies the detrimental effects on C assimilation and growth (Bakhshandeh et al., 2019; Dikšaitytė et al., 2019, 2020; Li et al., 2019; Pérez‐Jiménez et al., 2019; Siebers et al, 2017). Therefore, reduced transpirational cooling due to high leaf water pressure deficit leads to various direct and indirect effects on plants.…”

Soil microbial community responses to climate extremes: resistance, resilience and transitions to alternative states

“…One such indirect mechanism is a change in plant allocation and transfer of root-derived carbon to the soil microbial community in response to an extreme climatic event. Extreme drought, for example, reduces plant allocation of recent photosynthate to roots, which in turn reduces the transfer of plant-derived carbon to soil microbes, including root-associated mycorrhizal fungi [84][85][86][87][88][89]. This response is associated with differential uptake and turnover of plant-derived carbon by different groups of soil microbes, which modify intrinsic microbial community attributes that confer resistance and resilience [89,90].…”

Drought, heat, and their combined stress reduce the productivity and alter the photosynthetic characteristics of different alpine meadow plants

“…Research has shown that when heat and drought stress co-occur, they initiate various processes, such as the accumulation of large amounts of harmful substances in plants, a decreased photosynthetic rate by changing the activity of various enzymes involved in plant photosynthesis and metabolism coupled with abnormal respiration, closed stomata, high leaf temperature, and reduced water use efficiency in plants (Hao et al, 2019;Qaseem et al, 2019). Furthermore, various studies have demonstrated that the impact of heat and drought stress on plant growth, yield, and physiology varies among different crops (Bakhshandeh et al, 2019), which is also related to the different characteristics of each species. The effects on yield or any other trait may be synergistic, antagonistic, or hypo-additive (Pradhan et al, 2012;Prasad et al, 2011).…”