Recent global climate patterns have resulted in a higher occurrence of exceptionally high temperatures presenting substantial complications for agricultural productivity worldwide. Prolonged exposure to elevated temperatures, or heat stress, can cause irreversible damage to plant health. The intricate processes of plant growth and development, which rely on numerous temperature-sensitive biochemical reactions, are profoundly affected by the intensity and duration of heat events as well as the specific plant species involved (e.g., wheat). Therefore, a comprehensive understanding is essential to develop effective management strategies to mitigate heat stress and protect crop yield and quality. Heat stress occurring during critical growth stages can drastically reduce the productivity of staple food crops, threatening global food security. It can decrease agricultural output by up to 12% by impairing key physiological processes such as photosynthesis, reproduction and seed germination (decrease up to 25%). This review investigates how heat stress disrupts enzyme activities including rubisco, nitrate reductase, proteases, catalase, starch synthase and ATP synthase, leading to impairments in photosynthesis, carbohydrate metabolism, protein synthesis, anti-oxidative defense and regulation of phytohormones. These disruptions negatively affect plant growth and yield. By examining the roles of protective mechanisms, such as, heat shock proteins, enzymatic and non-enzymatic antioxidants (ascorbic acid, carotenoids, flavonoids, α-tocopherol, catalase, glutathione reductase, superoxide dismutase, and peroxidases), osmoprotectants (proline, glycine betaine, trehalose), phytohormones (abscisic acid, cytokinins and salicylic acid) and morphological adaptations, the review underscores the complexity and the interdependence of various defense systems in crop improvement strategies, focusing on the identification of key metabolic markers, stress-resilient traits and molecular targets for genetic enhancement.

Background: The effects of different photoperiods on plant phytochemical synthesis can be improved by adjusting the daily light integral. Photoperiod is one of the most important environmental factors that control growth, plant’s internal rhythm and the synthesis of secondary metabolites. Information about the appropriate standard in terms of photoperiod for growing basil microgreens as one of the most important medicinal plants is limited. In this study, the effects of five different photoperiods, 6 (6 h × 3 cycles), 8 (8 h × 2 cycles), 16, 18, and 24 h day^− 1 on the yield, photosynthesis and synthesis of secondary metabolites of three cultivars and one genotype of basil microgreens in floating system were evaluated. The purpose of this research was to determine the feasibility of using permanent light in growing basil microgreens and to create the best balance between beneficial secondary metabolites and performance. Results: The results showed that the effects of photoperiod and cultivar on all investigated traits and their interaction on photosynthetic pigments, antioxidant capacity, total phenolic compounds, proline content and net photosynthesis rate were significantly different at the 1% level. The highest levels of vitamin C, flavonoids, anthocyanins, yield and antioxidant potential composite index (APCI) were obtained under the 24-h photoperiod. The highest antioxidant capacity was obtained for the Kapoor cultivar, and the highest total phenolic compound and proline contents were measured for the Ablagh genotype under a 24-h photoperiod. The highest yield (4.36 kg m^− 2) and APCI (70.44) were obtained for the Ablagh genotype. The highest nitrate content was obtained with a photoperiod of 18 h for the Kapoor cultivar. The highest net photosynthesis rate was related to the Violeto cultivar under a 24-hour photoperiod (7.89 μmol CO₂ m^− 2 s^− 1). Antioxidant capacity and flavonoids had a positive correlation with phenolic compounds and vitamin C. Yield had a positive correlation with antioxidant capacity, flavonoids, vitamin C, APCI, and proline. Conclusions: Under continuous light conditions, basil microgreens resistance to light stress by increasing the synthesis of secondary metabolites and the increase of these biochemical compounds made basil microgreens increase their performance along with the increase of these health-promoting compounds. The best balance between antioxidant compounds and performance was achieved in continuous red + blue light. Based on these results, the use of continuous artificial LED lighting, due to the increase in plant biochemical with antioxidant properties and yield, can be a suitable strategy for growing basil microgreens in floating systems.

Basil is a great source of phytochemicals such as polyphenols, vitamin C, anthocyanin, and flavonoids. In this work, the biochemical compounds, antioxidant capacity, leaf color profile, and yield of 21 cultivars and genotypes of basil microgreen were investigated. Results showed that the highest antioxidant potential composite index (APCI) was measured in Persian Ablagh genotype (70.30). Twenty-one basil genotypes were classified into four clusters, including cluster 1 (lowest antioxidant capacity and total phenolic compounds), cluster 2 (lowest anthocyanin, vitamin C and APCI index), cluster 3 (highest vitamin C, total phenolic compounds, antioxidant capacity and APCI index), and cluster 4 (highest levels of anthocyanin). The principal components analysis (PCA) of basil genotypes showed diversity in terms of phytochemical components, and F1, F2, F3, and F4 explained the variation at the rate of 78.12%. The average annual temperature of the origin of basil seeds plays an important role in the synthesis of antioxidant content. Most of the seeds with moderate origin had a higher APCI index. The Persian Ablagh genotype, Violeto, and Kapoor cultivars can be recommended, according to their APCI index and yield. These cultivars can be used individually or in different ratios to produce different biochemical substances with different concentrations for various purposes.

Different LED light spectra (LS) are absorbed by different plant photoreceptors and can control biomass and plant secondary metabolite synthesis. In this study, the effects of continuous-spectrum LED lights (red, blue, white, red + blue, and 12 h blue + 12 h red) on the production value, antioxidant compounds, and biomass of basil (Ocimum basilicum L.) microgreens (Red Rubin, Violeto, and Kapoor cultivars and the Ablagh genotype) were investigated. The results showed significant effects of LS on cultivar (Cv) and the interaction of LS and Cv on the studied traits. The highest quantitys of chlorophyll a, total chlorophyll, and nitrate were obtained in Violeto under blue lighting. Red lighting enhanced starch synthesis in Red Rubin and flavonoids in the Violeto Cv. The highest biomass (4.54 kg m⁻²) was observed in the Ablagh genotype and the highest carbohydrate synthesis in Violeto Cv in the red + blue treatment. The highest anthocyanin content (26.33 mg 100 g⁻¹ FW) was observed for Red Rubin Cv under 12 h blue + 12 h red light. The greatest antioxidant capacity (83.57% inhibition), the highest levels of phenolic compounds (2027.25 mg GA 100 g⁻¹ FW), vitamin C (405.76 mg 100 g⁻¹ FW), proline, antioxidant potential composite index (APCI), and the greatest production values were obtained for the Ablagh genotype under blue lighting. Taken together, the experiment findings indicate that growing the Ablagh genotype under continuous blue lighting can increase the antioxidant capacity, phenolic compounds, and vitamin C and that this LED light spectrum can be used as a practical method to produce basil microgreens with high nutritional health value.

The appropriate concentration of the nutrient solution (NS) plays an important role in the yield, antioxidant capacity, and biochemical compounds of basil microgreens in the floating system. This study examined the impact of five different concentrations of Hoagland’s NS (25%, 50%, 75%, 100%, and 125%) on the antioxidant capacity, biochemical compounds, and yield of four basil cultivars and genotypes (Persian Ablagh, Violeto, Kapoor and Red Rubin) in a floating system, utilizing a split plots designs. Results revealed that the highest yield was achieved with a 50% NS concentration. The Persian Ablagh genotype, under a 125% NS concentration, exhibited the highest content of carotenoids, flavonoids, phenolic compounds, and antioxidant potential index (APCI). The Violeto cultivar at a 100% NS concentration produced the highest amounts of vitamin C and anthocyanin. The Kapoor cultivar, when grown with a 100% NS concentration, demonstrated the greatest antioxidant capacity. The nutrient solution with 125% concentration compared to 50% concentration reduced the yield by 23.29%. Also, the performance of the Violeto cultivar increased by 36.24% compared to the red variety of Robin. According to the APCI index, the genotype of Iranian Ablaq basil increased by 152.79% in the treatment of nutrient solution with a concentration of 125% compared to 50%. In this study, yield and total chlorophyll showed a significant negative correlation. A significant positive correlation was observed between vitamin C content and flavonoids, anthocyanin, phenolic compounds, and antioxidant capacity. Anthocyanin content exhibited a positive and significant correlation with the APCI. Based on these findings, we recommend a 50% NS concentration of Hoagland’s NS for optimal yield, a 125% NS concentration for the production of secondary metabolites with enhanced antioxidant capacity, and a 100% NS concentration as a balance between antioxidant properties and yield for basil microgreens production in a floating system.

Background: The rice-wheat cropping system is the prevailing agricultural method in the North-Western states of India, namely in the Indo-Gangetic plains. The practice of open burning of rice residue is frequently employed for expedient land preparation, but it has significant adverse impacts on both the environment and human health. These include the emission of greenhouse gases, loss of nutrients, elevated concentrations of particulate matter (PM), and disruption of the biological cycle. This research aims to investigate the implementation of effective management strategies in the rice-wheat cropping system, namely via the use of tillage-based crop cultivation techniques, stubble retention, and integration approaches. The objective is to enhance soil health features in order to augment crop yield and improve its attributes. Results: The research was carried out using a split plot experimental design, consisting of three replications. The main plot consisted of four different cultivation methods, while the subplot included three genotypes of both rice and wheat. The research demonstrates the enhanced efficacy of residue application is significantly augmenting soil nutrient concentrations compared to standard tillage practices (P < 0.05). This was accomplished by an analysis of soil nutrient levels, namely nitrogen (N), phosphorus (P), potassium (K), and organic carbon (OC), at a depth of 0–15 cm. The implementation of natural farming, zero tillage, and reduced tillage practices resulted in decreases in rice grain yields of 34.0%, 16.1%, and 10.8%, respectively, as compared to conventional tillage methods. Similarly, the implementation of natural farming, zero tillage, and reduced tillage resulted in reductions in wheat grain yields of 59.4%, 10.9%, and 4.6% respectively, in comparison to conventional tillage practices. Conclusion: Regarding the individual crop genotypes investigated, it was continuously observed that Him Palam Lal Dhan 1 and HPW 368 displayed considerably greater grain yields for both rice and wheat during the two-year experimental period. Furthermore, when considering different cultivation methods, conventional tillage emerged as the most effective approach for obtaining higher productivity in both rice and wheat. Additionally, Him Palam Lal Dhan 1 and HPW 368 exhibited superior performance in terms of various crucial yield components for rice (such as panicle density, grains per panicle, panicle weight, and test weight) and wheat (including effective tiller density, grains per spike, spike weight, and 1000-grain weight).