Extended Abstract
1. Introduction: Fruits and vegetables are important sources of beneficial nutrients in human nutrition and play a crucial role in reducing the risks of many diseases. The consumption of fruits and vegetables has a positive impact on diseases such as cardiovascular disease and certain types of cancer. These health benefits are related to the presence of vitamins, minerals, and dietary fibers, as well as a wide range of bioactive compounds, including phytochemicals, which influence free radical activity to maintain adequate levels of both enzymatic and non-enzymatic antioxidant defenses. Nowadays, many applications of biofertilizers and algae extracts have been proposed in agriculture, the food industry, and animal sciences. The use of SAE as a novel nutrient formulation containing protein and amino acids offers a new approach to supplying essential elements to plants. Unfortunately, few studies have been conducted on the use of SAE in agriculture, necessitating further research in this field. Therefore, considering the economic importance and increasing demand of biofertilizer, this research investigates the impact of SAE and biofertilizers on the Cape gooseberry (Physalis peruviana) plant.
2. Materials and Methods: Zarrouk's medium was used for the cultivation of Spirulina algae. The cultured samples were then harvested, dried at 45 degrees Celsius for 72 hours, and powdered. To extract the extract from the algae, the dried samples were first soaked in 80% methanol for 72 hours. The samples were subjected to ultrasonic waves three times, each for 15 minutes. Then, the resulting extracts were concentrated using a rotary evaporator at 45 degrees Celsius after a two-step filtration with Whatman filter paper No. 4. The Cape gooseberry seeds (Physalis peruviana) (Accession no: TN-82-765) used in this research were obtained from the Seed and Plant Improvement Institute of Iran. The seeds were sown in Petri dishes, and after germination, they were transferred to culture trays. The seedlings were kept in the culture trays for 30 days. Then, the plants were moved to a greenhouse, and after appropriate establishment of the plants (after two weeks), the treatments were applied as foliar spraying. The experiment was conducted as a factorial experiment based on a completely randomized design (CRD), consisting of foliar application of SAE at three concentrations (0, 0.25, and 0.5 percent) and Azotobacter biofertilizer at two levels (0 and 0.5 percent), with four replications. Foliar spraying was performed in three stages, with intervals of 15 days. Two weeks after the last foliar application, various morphological and biochemical traits were evaluated, including fruit fresh and dry weight, plant yield, titratable acidity, soluble solids, taste index, and biochemical parameters such as total flavonoid content, DPPH radical scavenging activity, and vitamin C concentration.
3. Results and Discussion: The results showed that the foliar application of SAE in the presence of biological fertilizer had a significant effect on yield traits, taste index, and Total Soluble Solids (TSS) in Cape gooseberry. During the evaluation of functional traits, it was observed that the highest fresh weight (4.498 g), dry weight (0.935 g), and plant yield (286.423 g) were obtained in plants treated with 0.5% SAE. Additionally, the results showed that the greatest effect in increasing the amount of the Total Phenol Content (TPC) (3.11 mg/g dry weight) in Cape gooseberry berries treated with 0.25% SAE  under conditions where biological fertilizer was applied at a concentration of 0. 5%. This amount was 12.42 percent higher than the control conditions. Similarly, the highest total flavonoid content (TFC) (1.811 mg/g dry weight) was recorded in plants treated with 0.5% SAE and 0.5% Azotobacter biofertilizer. The evaluation of the effects of spirulina algae extract on vitamin C and total antioxidant content indicated a positive impact on both parameters. The results showed that the highest levels of vitamin C and total antioxidants were obtained when Spirulina algae extract was applied at 0.5%.
4. Conclusion: Cape gooseberry is highly perishable, and several factors threaten its quality during cultivation and after harvest. According to the results of this research, it was found that the combined application of Azotobacter biofertilizer and Spirulina algae extract (SAE)had a significant effect on the yield and biochemical traits, particularly in plants treated with 0.5% SAE. Overall, the findings indicate that enhancing vitamin C and improving yield in Cape gooseberry plants is achievable through agricultural techniques. The application of Azotobacter biofertilizer and SAE significantly increased fresh weight, TSS, titratable acidity (TA), and total antioxidant activity in treated plants compared to untreated controls. Additionally, the positive effects of SAE at concentrations of 0.25% and 0.5%, in the presence of Azotobacter (0.5%), played a key role in increasing chlorophyll and carotenoid content, which in turn enhanced photosynthetic efficiency.. Therefore, to promote sustainable agriculture, it is recommended to replace chemical fertilizers with Azotobacter together in combination with SAE at different concentrations to achieve higher yields in Cape gooseberry cultivation.