**2. Responses to multiple stresses**

**1. Introduction**

146 Plant, Abiotic Stress and Responses to Climate Change

conditions.

regions [2].

Climate change is a reality that we must address using technology, scientific knowledge, and economic and social policies that modify the relationship between human society and its environment. Climate change already represents a multifaceted challenge for the sustainable production of food, for health, and in general for the culture and current patterns of level and quality of life of humans [1]. In the particular case of food production through field crops (cereals, oilseeds, vegetables, etc.), the expected scenarios indicate the increasingly frequent occurrence of unfavorable climatic events to agricultural production. This non-benign scenario forces the agricultural production processes to be modified and adjusted to a new reality [2]. Different techniques of agricultural production, such as the use of protected spaces (greenhouses, shade cloth, tunnels, and mulching) [3], modern genetic modification techniques [4], the implementation of translational processes based on systems biology [5], and the largescale implementation of vertical farms and plant factories [6] can provide some of the food needed for the growing human population. However, at this time getting the calories, minerals and fiber necessary for the feeding of humans and their domestic animals are still an

The shift to a system where 100% of the food for the population is produced on vertical farms and plant factories implies a profound change in the culture and food processes, such as reducing or eliminating meat consumption and food waste, among others [3]. Considering the above, it seems that crop production will still occur mostly using soils in open field production systems, so the expected greater magnitude of the stress associated with climate change does not seem to have a solution that depends entirely on the crop under protected

In any case, even with the expectation of having robotic systems, automation and abundant sources of energy, whether food production is carried out in the field, in a laboratory, or on a vertical farm or plant factory, in all the mentioned situations should be applied the concepts of sustainable production, care of natural resources, mitigation of environmental impact and pollution, since by definition any industrial process will have an impact on the environment [7]. On the other hand, even advanced industrial systems for food production such as vertical farms and plant factories depend on supplies such as water of a certain quality, high humidity in the air and an adequate range of temperatures for their cost-effective management, whose availability most likely will be dependent on processes associated with climate change and

On the other hand, under climatic change, the adjustments in the traditional patterns of distribution of precipitation, temperature, and atmospheric humidity, among others, are inevitable. It is possible that a modification in the form of new climatic conditions will be reached at a global level, which will inevitably prevail over a period that may be extensive on a human scale, but fleet at the scale of the climatic processes of the terrestrial system. Such an adjustment surely involves winners and losers as to the circumstances of food production in some

enterprise carried out almost entirely on soils in the open field [3].

the modification of environmental services.

In plants for cultivation, stress always occurs in a combined form, that is to say, there is not a single type of stress in isolation [9, 10]. It is known that in the scope of the description of the transcriptome, proteome, and metabolome, the combination of different stresses gives rise to different response profiles to those observed in the case of individual stress [8, 11]. That is, from a molecular point of view, the combination of two or more stresses generates a unique expression profile, which has made difficult the progress in obtaining transgenic crops with tolerance to multiple stresses [12].

However, when moving from the molecular scale to the areas of cellular and physiologicalmorphological description, biochemical and process-modulated responses to multiple abiotic stresses present typical responses to different stresses and their combinations. Among these are the induction of antioxidants, signaling molecules, chelating agents, compatible solutes, or osmolytes, specific hormone balances, chaperone proteins, regulation of the amount of N and foliar chlorophyll, control of stomatal opening and photosynthetic activity, induction of energy dissipation activities such as photorespiration and xanthophyll cycle and changes in growth rate and root/shoot ratios, among others [13, 14].

The induction of responses to one or more stresses activates a series of defense responses that have been described in the molecular, cellular or physiological-morphological domain. When a seed, seedling or plant is subjected to a stress stimulus with a degree of intensity that does not cause extensive damage in individuals, or when the concentration of one or more of the metabolites involved in responses to stress (antioxidants, osmolytes, etc.) is increased by means of exogenous applications or genetic manipulation, a phenomenon of partial activation of plant defenses occurs known as *hardening*, which allows that a post-stress exposure to cause minor damage to plants. When hardening occurs by prior exposure to a different type of stress, it is referred to as *cross-resistance*. The hardening technique has been widely reported as a mechanism of induction of stress tolerance.

It is likely that the defense responses, which initially manifest at the level subcellular, and organelles, but with a later impact on the physiological-morphological domain of the whole organism, depend on changes in cellular redox balance, which are the result of oxidative damage and disorganization of the energy transfer and information network which obeys


When stress is caused by multiple factors, it has been observed that the simultaneous application of several different mitigation measures results in a positive synergistic response of the plant [19]. Considering this, the application of agronomic practices aimed at the mitigation of the primary stresses for field crops can be carried out in two phases: the first one starting from the common component of stress due to excess PAR, the second considering the current knowledge about responses to stress in plants at the cellular and physiological level. The first

Tolerance-Induction Techniques and Agronomical Practices to Mitigate Stress in Extensive Crops…

tained way to the canopy of plants, and to maintain an abundant and biodiverse microbiome. The second phase refers to the potentially synergistic use of fertilizers, regulators, elicitors, and other chemicals to mitigate oxidative damage, in conjunction with tolerant varieties or landraces, irrigation systems, and tillage processes with less impact on the soil (**Table 1**). In an ideal situation, the practices mentioned for each phase should be applied simultaneously, although situations are also possible where only one part is applied, and positive results are

In this chapter, we present the measures that we propose to apply to the interaction domain of crop plants, soil, and atmosphere, that is, on the scale of an agricultural ecosystem. At this level (particularly in C3 species) the environmental factor irradiance seems to be a common confluence point for stress caused by multiple factors [20, 21]. As a consequence, mitigating the stress resulting from high levels of PAR in crop fields could reduce the impact of other

The management of the stress condition due to high irradiance, which is very common in C3 crops, depends on two main factors: the capacity of the edaphic system to contribute CO<sup>2</sup>

water in the time of maximum irradiance, as well as the efficiency of the photochemical and biochemical dissipation processes that produce thermal energy and ROS, in addition to the plant ability to reduce the impact of the products of dissipative processes on the biochemical and physiological processes that determine growth and reproduction. For the first factor, the key to management is the soil condition, especially the content of organic matter and the promotion of the microbiome of plants. Also, other measures can be applied such as the reduction of tillage, the use of high-efficiency irrigation systems and the use of hydrophilic polymers. For the second factor, the ability (intrinsic, improved, or genetically modified) to tolerate the stress of each species or variety is considered, as well as the use of various substances or mineral elements that function as tolerance inducers (such as Si, Se, and various nanomaterials of Fe, Zn, etc.), antioxidants, and substances or materials that modify foliar

Solar radiation is the primary source of energy for the photosynthetic process. With the cur-

concentration (400 μL L−1), a significant part of the CO<sup>2</sup>

stress-inducing environmental factors such as water deficit, salinity, and heat.

in a sus-

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http://dx.doi.org/10.5772/intechopen.71771

and

used

phase refers to the management of the soil capacity to store water, to contribute CO2

obtained.

**3. High irradiance stress**

reflectance or the use of radiation (**Figure 1**).

 **availability**

**3.1. Irradiance and CO2**

rent condition of atmospheric CO2

**Table 1.** Use of management strategies in different stages of cultivation for abiotic stress mitigation in plants.

the structure of the membranes, their integral proteins and their interaction with the cytoskeleton [15]. In other organizational scopes, such as ecosystems, similar phenomena have been described where disruption in some system components (by example, a decline in biodiversity) has a negative impact on energy efficiency [16, 17].

The proper use of energy by a system is probably the primary process affected during a stressful situation. It is desirable and possible to moderate the damage caused by energy imbalance, not only at the molecular level but also in the description scope of cells, organisms, and ecosystems. At each level, appropriate measures would be applied, depending on the properties that can be manipulated in each scope. Each of the actions in the different fields would synergistically contribute to the mitigation of crop stress. These multiple approaches, which should ideally be comprehensive, contemplate different levels of description and response of the productive system and are expected to improve the ability to adapt and produce food under the climate change scenarios [18].

When stress is caused by multiple factors, it has been observed that the simultaneous application of several different mitigation measures results in a positive synergistic response of the plant [19]. Considering this, the application of agronomic practices aimed at the mitigation of the primary stresses for field crops can be carried out in two phases: the first one starting from the common component of stress due to excess PAR, the second considering the current knowledge about responses to stress in plants at the cellular and physiological level. The first phase refers to the management of the soil capacity to store water, to contribute CO2 in a sustained way to the canopy of plants, and to maintain an abundant and biodiverse microbiome. The second phase refers to the potentially synergistic use of fertilizers, regulators, elicitors, and other chemicals to mitigate oxidative damage, in conjunction with tolerant varieties or landraces, irrigation systems, and tillage processes with less impact on the soil (**Table 1**). In an ideal situation, the practices mentioned for each phase should be applied simultaneously, although situations are also possible where only one part is applied, and positive results are obtained.

In this chapter, we present the measures that we propose to apply to the interaction domain of crop plants, soil, and atmosphere, that is, on the scale of an agricultural ecosystem. At this level (particularly in C3 species) the environmental factor irradiance seems to be a common confluence point for stress caused by multiple factors [20, 21]. As a consequence, mitigating the stress resulting from high levels of PAR in crop fields could reduce the impact of other stress-inducing environmental factors such as water deficit, salinity, and heat.
