Agro-photovoltaics (APV) could be the optimal means of sustainable development in agricultural areas once a few challenges are overcome, perhaps the greatest of which is the constant shading from AVP structures. This study examined how the growth and yield of rice, potato, sesame, and soybean crops could be optimized when grown underneath different APV systems. The solar radiation, shading levels, and temperatures during crop cultivation were measured. In addition, the photosynthetic efficiency was measured at different growth stages. Adjacent to the APV systems were the control plots with full sun. In these studies with potato crops grown under APV systems, most growth and yield parameters were similar to those grown in the control plot except for the plant height. On the other hand, sesame crops grown underneath the APV systems had a lower stem length, effective branching number, 1000 seed weight, and a reduced yield of 19% compared to the crops from the control plot. In two distant locations (Paju and Youngkwang), soybean crops grown underneath APV systems at both sites showed increased ungrained ratios per pod and a reduced yield of 18–20% compared to the control plot. Finally, rice crops cultivated underneath the APV systems had a lower panicle number per hill, spikelet number per panicle, 1000 seed weight, and yield reduction of 13–30% compared to the control plot. Overall, crops grown underneath the APV systems had a greater plant height and stem length. Moreover, the solar radiation and PAR underneath the APV systems were also lower than in the control plots. The photosynthetic efficacy in rice plants grown underneath the APV systems was lower than in the control plots. The photosynthetic efficacy may help lower the crop yield when cultivation is underneath an APV system.

Though the mechanisms are not yet fully understood, the macro-and micro-nutrients, amino acids, and hormone-like growth substances present in plants (whole plants and their extracts) may lead to biostimulatory activities when applied to crops. This study was conducted to determine the growth promotion effects on lettuce (Lactuca sativa L.) of plant extracts obtained by different extraction methods (water, boiling water, fermentation, and ethanol) from 31 agricultural materials. We also determined the growth promotion effects of three other leguminous crop extracts on lettuce. In total, these 31 different agricultural materials produced 82 different extracts. The most effective extracts were water and boiled water extracts of Chinese chive (Allium tuberosum), water extracts of soybean leaves (cvs. Daewon and Haepum), and water, fermentation, and ethanol extracts of soybean stems (cv. Daewon). These induced a 31-45% increase in shoot fresh weight of lettuce compared with control plants. Chinese chive, soybean leaf, and soybean stem extracts had a greater impact on shoot fresh weight of lettuce when applied at 20 days after seeding (DAS) than when applied at 30 and 40 DAS. In addition, when extracts from Chinese chive and soybean leaf and stem were used, the shoot fresh weight of lettuce was higher at 7 days after treatment (DAT) than at 14 and 21 DAT. The shoot fresh weight of lettuce was 13-15% higher when the selected extracts were applied twice instead of once. Moreover, the growth promotion effects of the selected plant extracts were also observed in endive and broccoli, but not in pak choi and kale. Additionally, the growth promotion of lettuce was higher in response to soybean leaf and stem extracts than extracts of other leguminous crops (cowpea, mung bean, and red bean). The selected extracts showed higher growth promotion effects on lettuce than those of urea and a commercial extract. Overall, the results indicate that the selected plant extracts can be used for growth promotion in organic cultivation of various crops.

Abiotic stressors such as drought, salinity, waterlogging, and high and low temperatures significantly reduce the growth and productivity of rice (Oryza sativa) and soybean (Glycine max), which are vital for global food and nutritional security. These stressors disrupt physiological, biochemical, and molecular processes, resulting in decreased yield and quality. Biostimulants represent promising sustainable solutions to alleviate stress-induced damage and improve crop performance under stressful conditions. This review provides a comprehensive analysis of the role of biostimulants in enhancing rice and soybean resilience under abiotic stress. Both microbial and non-microbial biostimulants including phytohormones such as salicylic acid; melatonin; humic and fulvic substances; seaweed extracts; nanoparticles; and beneficial microbes have been discussed. Biostimulants enhance antioxidant defenses, improve photosynthesis and nutrient uptake, regulate hormones, and activate stress-responsive genes, thereby supporting growth and yield. Moreover, biostimulants regulate molecular pathways such as ABA- and ROS-mediated signaling and activate key transcription factors (e.g., WRKY, DREB, NAC), linking molecular responses with physiological and phenotypic resilience. The effectiveness of biostimulants depends on crop species, growth stage, stress severity and application method. This review summarizes recent findings on the role of biostimulants in enhancing the mechanisms underlying growth, yield, and stress tolerance of rice and soybean under abiotic stress. Additionally, the incorporation of biostimulants into sustainable farming practices to increase productivity in the context of climate-related challenges has been discussed. Furthermore, the necessity for additional research to elucidate the underlying mechanisms, refine application methods, and verify their effectiveness in field conditions has been highlighted.

This study examined the effects of changes to application methods, application time, and combinations of different extracts on the growth and yield of cucumbers. Chlorophyll and photosynthetic efficiency levels in cucumber plants were also measured after receiving treatments of selected liquid fertilizers. Mineral nutrition levels in both extracts themselves and the test plants were measured. Crude protein, crude fat, ash, total phenol and flavonoid contents, and DPPH radical scavenging activity in cucumber were determined. Cucumber plant height and shoot fresh weight at 7 and 14 days after treatments generally increased significantly regardless of the extraction methods or extract materials. On the other hand, cucumber leaf number was similar regardless of the extracts used. The application frequency effects differed according to the extraction methods, extracts, and parameters investigated. In addition, the combinations of extracts did not produce significant increases in cucumber plant growth. Cucumber fruit weight was 17–81%, 10–61%, and 10–45% higher than the control or oil cake when the plants were treated with fermentation, boiled water, and water extracts, respectively. The chlorophyll content and photosynthetic efficiency of cucumber plants treated with various extracts did not vary significantly. Extracts with the highest mineral nutrients were not effective growth promotors of cucumber plants. This means that growth promotion may not be caused by high levels of one specific macro or micro element but by some specific combinations of various elements. Compared to the control, most elements in the cucumber leaves decreased significantly when treated with most of the extracts. Generally, crude protein, crude fat, and ash contents were not negatively affected by the extract treatments. Moreover, most of the extracts did not adversely affect total phenol and flavonoid contents and DPPH radical scavenging activity. Thus, these extracts may be used for growth promotion without negative effects to primary and secondary substances in organically cultivated crop fields.