The Adaptation of Crops to the Environment under Climate Change: Physiological and Agronomic Strategies—Volume II

This Special Issue “Adaptation of Crops to the Environment under Climate Change: Physiological and Agronomic Strategies—Volume II” compiles eleven original research articles, addressing different strategies to cope with the current climate change scenario. These solutions come from the application of compounds to increase water stress, the selection of the most resistant cultivar to heat stress, and the comparative approach between different growth conditions in response to salt stress, among others.

Climate change is one of the biggest challenges for humanity today. Its effects are becoming increasingly evident in different sectors, and agriculture is no exception. Crops are affected by rising temperatures, variability in rainfall, and other extreme weather events. Agriculture is one of the most vulnerable sectors to climate change due to its direct dependence on environmental conditions. Increased temperatures can alter crop growth cycles, affecting their yield and quality. Additionally, rainfall variability can cause floods or droughts, which in turn impact yield. In this sense, it is crucial that farmers adopt sustainable and climate-resistant practices to mitigate its negative effects. Developing strategies to cope with this new scenario is a major challenge for 21st-century agronomy. This ambitious objective cannot be undertaken with a single strategy, so solutions may come from biotechnology, microbiology, ecophysiology, engineering, and organic farming.

This Special Issue includes contributions from Spain, Portugal, Tunisia, Italy, Germany, France, Czech Republic, and Turkey, but also China, Australia, Saudi Arabia, Iran, India, Nigeria, South Africa, Pakistan, Thailand, and Bangladesh. As such, these very different locations provide diverse approaches and strategies that are being carried out in different crops and agricultural ecosystems.

Foliar application of minerals or chemical products is a methodology to promote growth and yield and to increase tolerance against different kinds of stresses. The paper authored by Ghiyasi et al. [1] evaluated and compared the effect of foliar application of zinc oxide (ZnO) and zinc oxide nanoparticles on the growth and yield of safflower under different irrigation regimes. The results showed that foliar application of ZnO improves safflower yield especially under drought conditions and that the use of nanoparticles increases the efficiency of the application. On the other hand, Molla et al. [2] applied 2-chloroethyl phosphonic acid (ethephon) to maize plants in order to investigate its stimulatory effects on the morpho-physio and biochemical traits of this crop under water stress. Ethephon is a synthetic bioregulator that positively absorbs and subsequently releases ethylene into plant tissues and is used to control the plant canopy size or used as an anti-lodging agent in maize.

High temperature is one of the environmental stresses that has the greatest impact on the production of some crops, especially in the Mediterranean area. Therefore, there is a real need to increase heat tolerance in important crops, such as soybeans and corn. Rani et al. [3], from Pakistan and South Africa, evaluated 203 soybean accessions from different global climatic zones for adaptability under long-day conditions. The authors identified some accessions which were able to produce the highest yield; therefore, these accessions could be recommended for general cultivation under long-day and high-temperature conditions. In this sense, Zhang et al. [4] examined four wheat cultivars for 3 days at the meiosis and anthesis stages to evaluate the response and recovery to heat stress. They found significant differences in the adaptability of these four cultivars to high temperatures. The study highlights the importance of selecting heat-tolerant cultivars and understanding the physiological mechanisms of heat sensitivity for wheat breeding programs aimed at enhancing resilience to high temperatures.

In this Special Issue, several articles focusing on the adaptation of crops to the environment under climate change, from a purely agronomic point of view, have been published. In Wu et al.’s study [5], long-term field experiments conducted from 2014 to 2021 in several maize-producing areas of China evaluated the effects of different planting densities on maize yield and climate resource utilization. This study found that higher planting densities (8.6 × 10⁴ plants ha⁻¹ or 8.0 × 10⁴ plants ha⁻¹) significantly improved yield and resource use efficiency. The results highlight the importance of optimizing planting density to maximize yield and adapt to local climate conditions, particularly in the context of increasing temperatures. Cowpea, often grown in intercropping systems in West Africa, faces challenges in realizing its yield potential. A study published by Omoigui et al. [6] evaluating newly developed cowpea breeding lines for intercropping systems identified two lines, UAM14-122-17-7 and UAM14-123-18-3, which performed well in both sole and intercropping systems across different agroecological zones. These lines showed superior grain and fodder yields, demonstrating their adaptability and potential to enhance cowpea production in mixed cropping systems. On the other hand, rice–wheat rotation is a widely adopted multiple-cropping system in some regions. In Yang et al.’s study [7], a field experiment conducted in Jiangsu Province, China, from 2020 to 2022, examined the impact of various nitrogen (N) fertilizer application rates on rice–wheat rotation systems. This study utilized life-cycle assessment to evaluate environmental impacts, yield, and economic profits across 30 different treatments. The results indicated that the optimal N application strategy was 300 kg N ha⁻¹ for rice and 240 kg N ha⁻¹ for wheat, which provided the best balance between yield and environmental sustainability. However, the study also highlighted the substantial environmental footprint of urea production and application, suggesting the need for more sustainable N fertilizer management practices.

To minimize negative impacts on the environment there are a series of sustainable soil management practices aimed at maintaining or improving the quality, health, and productivity of soil. One of them is a legume cover crop. Martins et al.’s study [8], assessing the effects of conventional tillage, legume cover crops, and natural zeolites on soil health and olive yield found that natural zeolites significantly improved soil properties and olive yield. The combination of leguminous cover crops with zeolites enhanced photosynthetic activity, tree nutritional status, and soil moisture. This approach shows promise for sustainable soil management in rainfed olive orchards, offering a pathway to mitigate the adverse effects of climate change and preserve soil health.

In the face of escalating climate change and sustainability challenges, innovative agricultural practices and crop management strategies are becoming increasingly crucial. Digital tools and mathematics are useful for designing and optimizing future climatic scenarios. In relation to this, Garin et al. [9] focused on pearl millet cultivation in India. A study analyzing district-level data from 1998 to 2017 identified five distinct cultivation environments, with two showing notable growth and three exhibiting a decline. This study suggests that economic factors and potential rain increases may drive the transition to more profitable crops like cotton or maize. These insights provide a foundation for optimizing pearl millet production systems and adapting to future climatic options. On the other hand, based on agricultural climatic suitability theory and the fuzzy mathematics method, Wang et al. [10] carried out a study focusing on the climatic suitability of sesame in China from 1978 to 2019. Sesame, a high-quality oilseed crop, faces significant challenges due to changing climate conditions. The results reveal that temperature and precipitation have increased, while sunlight hours have decreased. This climatic shift has impacted sesame growth, with a general decline in climatic suitability observed. These findings underscore the importance of strategic agricultural planning and adaptation to optimize sesame cultivation amidst climate change.

In order to know the best cultivation conditions for a crop under climate change, comparative studies are of great value. In this Special Issue, readers will find one performed with quinoa since this crop’s ability to tolerate high salt levels offers a solution to agricultural challenges posed by salinity. The study published by Slimani et al. [11] comparing the salt tolerance of three quinoa accessions under greenhouse and field conditions found that greenhouse conditions enhanced growth and salt tolerance. The DE-1 accession exhibited the highest salt tolerance, maintaining better photosynthetic activity and lower oxidative stress markers under high salinity. This research underscores the potential of greenhouse cultivation to improve quinoa’s resilience to salt stress and suggests further exploration of the genetic factors underlying salt tolerance.

In conclusion, this Special Issue includes eleven contributions that collectively emphasize the need for innovative agricultural practices and advanced technologies to address the challenges posed by climate change and sustainability. From optimizing fertilizer management and soil health to enhancing crop resilience to drought, heat, and salinity, these research findings provide valuable strategies for sustaining agricultural productivity. As the global climate continues to change, the adoption of such practices will be essential for ensuring food security and environmental sustainability.