Fruit production and SPAD index of pepper (Capsicum annuum L.) under nitrogen fertilizer doses

摘要

The availability of nitrogen (N) in the soil influences the vegetative development of plants. However, the requirement is usually different between crops. The objective of the present work was to determine the fruit production and the SPAD index of pepper submitted to different amounts of nitrogen applied to the soil and applying this index in the production prognostic of the crop. The experiment was carried out under greenhouse conditions, Paraíba State, Brazil. The treatments were carried out in a completely randomized design, in a 3 × 5 factorial experiment, i.e., All Big, Yolo Wonder and Vermelho Samurai-Sais cultivars and five nitrogen fertilization doses (0, 33.33, 66.67, 100 and 133.33 mg kg -1 soil) with three replicates. At the time of flowering and harvesting of the peppers, the SPAD index was determined, using chlorophyll meter. The total production of fruits per plant was obtained weighing the fruits. Pepper production of all cultivars increased with nitrogen application at 120 days after sowing, using different soil nitrogen applications to reach their maximum productions. The Yolo Wonder cultivar had the maximum production (483.7 g of fruit/plant). The plants that presented SPAD index of 58.5 in the flowering stage showed the maximum fruit yield. The quantification of the SPAD index at the reproductive stages can be used in the prognosis of pepper production.