Increase in anthocyanins and their relationship with nutrition, stomatal density, and yield of purple lettuce (Lactuca sativa L.) nourished with humus based on vegetable waste

Abstract Global food security faces challenges due to the geopolitical situation, climate change, unhealthy diets, and the post-pandemic period. In Peru, the effects of the socioeconomic crisis were also felt, especially in the increase in food prices. For this reason, research was conducted on the increase of anthocyanins and their relationship with nutrition, stomatal density, and the yield of purple lettuce nourished with humus based on vegetable waste (HBVW). The objective was to determine the increase in anthocyanins in relation to nutrition, stomatal density, and the yield of purple lettuce nourished with HBVW. The methodology is based on applied research with an experimental approach; for this, a completely randomized block design was used, consisting of 3 blocks and 5 treatments, which were T1 with 0, T2 with 6, T3 with 8, T4 with 10, and T5 with 12 t ha-1 of HBVW. The doses were applied 15 days after transplanting, and physical characteristics were evaluated (total plant length, weight of purple lettuce, diameter of purple lettuce, and commercial yield), nutrient concentration in leaves (nitrogen, potassium, phosphorus, calcium, magnesium, sulfur, molybdenum, iron, manganese, copper, zinc, boron, chlorides, and sodium), anthocyanin concentration, total nitrogen, and phosphorus consumption. Also the stomatal density and profitability. Results determined that T5 stood out in total plant length with 28.90 cm, lettuce weight with 96.33 g, diameter with 17.07 cm, and commercial yield with 19.387 t ha-1. Total nitrogen consumption with 291.44 kg ha-1 and total phosphorus pentoxide consumption with 412.98 kg ha-1 and profitability with 88.4%. Nutrient concentration in T4 leaves with sulfur, molybdenum, manganese, copper, zinc, and boron. Anthocyanin concentration T2 with 364.62 mg/100 g and stomatal density T1 with 460 stomata/mm2. He concluded that the appropriate dose (T4) significantly stood out in anthocyanin concentration and yield. This dose provided nutrients to the soil that improved availability for greater absorption by the plant, which influenced higher nutrient concentration and an adequate number of stomata in the leaves. These biochemical characteristics optimized the reactions of photosynthesis, carbohydrate formation, and translocation and increased anthocyanin synthesis. Resulting in a strengthening against nutritional and environmental stress, pests, and reactive oxygen species (ROS).