Heat stress, a major challenge in modern agriculture due to global warming, significantly reduces crop productivity. To mitigate its adverse effects on maize yield, it is crucial to understand the mechanisms by which heat stress impacts reproductive development. This study investigated the impact of heat stress during the 12th leaf (V12) stage, where silk development begins on grain yield formation, using heat-sensitive and heat-tolerant cultivars. Compared to pollen, silks were found to be more vulnerable to heat stress. Heat stress disrupted hormone balance and inhibited hormone signaling transduction pathways in silks, delaying silk emergence from bracts and reducing fertilization and grain yield. The heat-tolerant cultivar maintained silk growth by activating more response pathways, displaying faster hormone responses, and up-regulating hormones. Taken together, we propose that hormones play an essential role in silk development and later fertilization process.

To make agricultural systems sustainable in terms of their greenness and efficiency, optimizing the tillage and fertilization practices is essential. To assess the effects of tilling and fertilization practices in wheat–maize cropping systems, a three-year field experiment was designed to quantify the carbon footprint (CF) and energy efficiency of the cropping systems in the North China Plain. The study parameters included four tillage practices (no tillage (NT), conventional tillage (CT), rotary tillage (RT), and subsoiling rotary tillage (SRT)) and two fertilizer regimes (inorganic fertilizer (IF) and hybrid fertilizer with organic and inorganic components (HF)). The results indicated that the most prominent energy inputs and greenhouse gas (GHG) emissions could be ascribed to the use of fertilizers and fuel consumption. Under the same fertilization regime, ranking the tillage patterns with respect to the value of the crop yield, profit, CF, energy use efficiency (EUE) or energy productivity (EP) for either wheat or maize always gave the same sequence of SRT>RT>CT>NT. For the same tillage, the energy consumption associated with HF was higher than IF, but its GHG emissions and CF were lower while the yield and profit were higher. In terms of overall performance, tilling is more beneficial than NT, and reduced tillage practices (RT and SRT) are more beneficial than CT. The fertilization regime with the best overall performance was HF. Combining SRT with HF has significant potential for reducing CF and increasing EUE, thereby improving sustainability. Adopting measures that promote these optimizations can help to overcome the challenges posed by a lack of food security, energy crises and ecological stress.

With global warming, high-temperature (HT) stress has become a major abiotic stress for crops, in particular summer maize in China. Photosynthesis is sensitive to HT. Salicylic acid (SA) and 6-benzyladenine (6-BA) can improve the adaptation of plants to various biotic and abiotic stresses. However, their contribution to maintaining photosynthetic activity and alleviating photoinhibition in maize leaves under HT stress is still unclear. The effects of exogenous SA or 6-BA on growth, photosynthesis capacity, photosystem Ⅱ (PSII) activity, subcellular ultrastructure, antioxidant system, and plant hormones in maize leaves under HT stress were investigated. Under HT conditions, application of SA or 6-BA up-regulated gibberellin and zeatin content in leaves, increasing leaf area index (LAI). It also expanded the stomata by reducing abscisic acid and jasmonic acid content in leaves, cooling them and increasing CO₂ supply to photosynthesis. A higher net photosynthetic rate, combined with increased activity of the antioxidant system, alleviated oxidative stress in maize plants sprayed with SA or 6-BA, allowing them to maintain their chloroplast ultrastructure and PSII activity, in particular electron transfer from Q_A to Q_B. The increased LAI and net photosynthetic rate per unit leaf area also resulted in the accumulation of more biomass.