Pre-harvest treatments of pepper plants with nitrophenolates increase crop yield and enhance nutritive and bioactive compounds in fruits at harvest and during storage

Abstract

Pepper plants (Capsicum annuum L. cv Lamuyo) were treated with a mix of nitrophenolates either by foliar spray or in the irrigation system, and its effect on crop yield and the content of nutritive and bioactive compounds in fruit were analysed at harvest and after post-harvest storage. Treatments were applied at 2-week intervals from the development of first floral bunch (1 March) to end of August. Pepper fruits were harvested at commercial ripening stage (red surface colour) along the growth cycle (from May to September). Total yield (cumulative kilogram per plant) was increased ( 4.5% more) by nitrophenolate treatments due to significant increases in fruit mass, although the number of fruits per plant was unaffected. Pepper fruit quality (weight, firmness and pericarp thickness), its content in nutritive (sugars and organic acids) and bioactive compounds (vitamin C and total phenolics) and antioxidant activity were also enhanced by nitrophenolate treatments at the three harvested dates assayed (end May, mid July and end August). In addition, all these parameters were maintained at higher levels in treated peppers during storage, while diminutions in these parameters occurred generally in control fruit. Thus, nitrophenolate treatments were able to improve crop yield as well as the nutritional value and antioxidant properties of peppers at harvest and after fruit storage.