Growth Curve and Nutrient Accumulation in Lettuce for Seed Production Under Organic System

Phosphorus compromises seed productivity and quality, highlighting the need for studies that define the nutritional requirements for organic cultivation. Thus, the objective of this study was to determine the dry mass and macronutrient accumulation curve in lettuce for seed production, aiming at cultivation in an organic system. The treatments consisted of two phosphorus doses (320 and 800 kg ha-1 of P2O5, Yoorin® thermophosphate source). The crisp lettuce plants, cultivar Solaris, were collected at eight stages (0, 14, 28, 42, 56, 70, 84 and 98 days after transplanting - DAT) for analysis of the proposed characteristics. The results demonstrated continuous plant growth, accompanied by a gradual increase in dry matter throughout the experimental period, regardless of the phosphorus dose studied. The dose of 800 kg ha-1 of P2O5, the lettuce plant accumulated 1527.7, 308.2, 2922.6, 1658.4, 416.0 and 197.6 mg per plant of N, P, K, Ca, Mg and S, respectively. The dose of 320 kg ha-1 of P2O5, the lettuce plant accumulated 1743.1, 256.9, 2575.7, 1210.2, 358.8 and 185.5 mg per plant of N, P, K, Ca, Mg and S, respectively. The greatest demand for nutrients in the plant occurred between 55 and 88 DAT.