Adaptive Responses to Nitrogen and Light Supplies of a Local Varieties of Sweet Pepper from the Abruzzo Region, Southern Italy

Abstract

Local varieties represent a heritage for plant biodiversity and, thanks to their resilience, are characterized by a better adaptation and rusticity to environmental variables. This work reports the morphological and physiological responses of a local ecotype of sweet pepper grown in Southern Italy, i.e., Altino, to N and light supplied at optimal and sub-optimal levels. In 2017, two open-field experiments were set up, comparing increasing N rates (0, 100 and 200 kg N ha−1, 0_N, 100_N and 200_N, respectively) and different percentages of shading and/or manipulations of the transmitted solar radiation, obtained through photoselective nets (red net, RN; black net, BN; unshaded Control). The unfertilized plants reduced growth (by 32% on average, at 83 days after transplanting, DAT), especially in terms of number of leaves, leaf area and effectiveness (chlorophyll content) of photosynthetic apparatus; no differences were recorded among fertilization treatments. On the other hand, the shading avoidance mechanisms resulted in higher biomass partitioned to leaves at the expense of sink organs, the building of more expanse (higher total leaf area) and thinner (higher specific leaf area and lower leaf-cuticular waxes) photosynthetic apparatus, and in a greater concentration of leaf pigments. The effects on yield and fruit quality of Altino ecotype deserve to be further explored.