Effects of foliar applications of commercial seaweed and spirulina platensis extracts on yield and fruit quality in pepper (Capsicum annuum L.)

Recently, resource consumption and population growth have negatively impacted the environment. The use of algae as biofertilizers or biostimulants is one of the most innovative agronomic techniques as an alternative to chemicals. It holds promise for the development of sustainable agricultural systems. Accordingly, this study aimed to determine the effects of spirulina (a microalgae species) and brown seaweed (a macroalgae species) on the yield and quality of peppers. A total of 7 applications [seaweed (2000 ppm, 4000 ppm, and 6000 ppm), spirulina (2000 ppm, 4000 ppm, and 6000 ppm), and control] were carried out 3 times at 21-day intervals from the seedling planting. Parameters such as yield per plant, number of fruits, fruit weight, fruit length, fruit width, stem diameter, fruit flesh thickness, fruit colors, chlorophyll content, titratable acidity, vitamin C, total/reducing sugars, total phenolic, and ss-carotene were analyzed. The results showed that both spirulina and seaweed applications had a positive effect on the yield and quality parameters of pepper, however, spirulina applications provided better results in terms of yield parameters. The highest yield (g/plant) values were obtained in all spirulina treatments. While the highest fruit weight (26.50 g) and fruit width (23.52 mm) values were determined in the 4000 ppm spirulina application, the highest fruit length value (21.55 cm) was obtained in the 6000 ppm spirulina application. Fruit numbers ranging between 92.01 and 115.35 and chlorophyll (SPAD) values ranging between 70.89 and 78.97 were highest in 2000 ppm spirulina application.