Field Crop 2025, Vol.8, No.5, 213-221 http://cropscipublisher.com/index.php/fc 214 promising genotypes and technologies, and proposes feasible adaptation strategies to provide a comprehensive framework for stakeholders (farmers, breeders, and policymakers) to implement climate-smart cotton cultivation, ensuring sustainable production and improved livelihoods under changing climate conditions. 2 Physiological Responses of Cotton to Drought and Heat Stress 2.1 Root development and stomatal regulation under water deficit When there is a shortage of water, cotton has more than one way to deal with it. The most direct one is usually that the root system "roots down" even deeper. In this way, even if the surface cracks, the deep moisture still has a chance to be absorbed. During drought periods, this change in the root system is actually one of the fundamental strategies for cotton to sustain its life. However, the above-ground parts also "subtract" - for instance, the closure of stomata is almost the most common response of the plant. Closing the stomata can reduce water evaporation, but the problem is that it also prevents carbon dioxide from entering, and thus photosynthesis drops. This balance is mainly regulated by abscisic acid (ABA). Although it can save lives, the side effect is that the yield is often sacrificed as well (Ullah et al., 2017). Not all varieties perform the same. Some cotton genotypes can maintain a high stomatal conductance and relative moisture content under pressure, and thus are more drought-tolerant (Anwar et al., 2021). 2.2 Effects of high temperature on photosynthesis, boll retention, and fiber development When a heat wave hits, the first function of cotton to "fail" is photosynthesis. The incoordination of stomatal switches is one aspect, but the inactivation of key enzymes (such as Rubisco) and the damage to chloroplast structure are actually more fatal internal causes (Carmo-Silva et al., 2012). Further down, as the temperature rises, the flowers and cotton bolls are prone to dropping, the development cycle shorts, and the final harvest is naturally affected. Don't have too much hope for the quality either (Abro et al., 2023). The worst-case scenario is that high temperatures and drought occur simultaneously, causing the retention rate of cotton bolls to drop directly, and the decline in seed cotton yield is almost inevitable (Bista et al., 2024; Zhang et al., 2024). 2.3 Oxidative stress and resistance responses under combined drought and heat stress Under dual stress, it's not just a matter of water and heat; oxidative stress also rises. Reactive oxygen species (ROS) such as hydrogen peroxide and malondialdehyde began to accumulate in the cells (Zafar et al., 2023), which was another blow to cotton. Some drought-resistant genotypes can rapidly mobilize the defense system. The activities of antioxidant enzymes such as superoxide dismutase and catalase will increase, and the levels of protective metabolites such as proline and phenols will also increase simultaneously (Figure 1) (Sekmen et al., 2014; Hasan et al., 2018). With these biochemical defense lines, plants can somewhat preserve their cellular structure, but this mechanism is not equally effective in all varieties, and the performance differences are quite obvious. 3 Overview of Climate-Smart Agronomic Practices 3.1 Water-saving tillage practices: mulching, ridge-furrow, and deep tillage Drip irrigation cannot be rolled out everywhere, especially in areas with limited water resources and insufficient investment. At this point, some seemingly "not-so-new" water-saving methods come into play, such as covering the ground with plastic film, deeply loosening the soil or using furrow cultivation. Many experiments have confirmed that they can indeed help cotton fields reduce water evaporation, and some can even improve soil structure and regulate temperature incidentally. Ridge cultivation can also conveniently solve drainage problems in areas with uneven terrain or sudden heavy rain (Khalid et al., 2025). In addition, "labor-saving" management methods such as laser land leveling and less plowing, although not as technologically advanced as drip irrigation, are no less effective in improving water utilization and reducing soil erosion. They are even more suitable for long-term use by small and medium-sized farmers. 3.2 Crop rotation and intercropping strategies to enhance resource use efficiency It's not that cotton should be planted every year. Sometimes, alternating planting can actually yield better results. For instance, some regions choose to rotate legumes or grains in cotton fields or arrange some cover crops before and after the cotton season. The results show that the soil becomes looser, nutrients are more stable, and pests can
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