Growth of “Biquinho” Pepper Plants under Salt Stress in a Hydroponic System

Abstract

In the absence of matric potential, the hydroponic cultivation method of employing brackish water to prepare a nutrient solution permits satisfactory growth, even of non-leafy vegetables. The present study evaluated the growth variables, stem diameter, plant height, number of leaves, and the shoot dry mass in the different phenological stages of “Biquinho” pepper in response to the electrical conductivity of the nutrient solutions (ECsol), varying from 2.70 to 7.77 dS m−1 in a Nutrient Film Technique (NFT) hydroponic system. For the number of leaves, linear reductions of 3.89 and 9.29% (dS m−1)−1 were observed at 10 and 30 days after transplanting (DAT), respectively. At 60 DAT, plants began to preserve their leaves up to ECsol of 4.60 dS m−1 and presented a linear decrease of 23.32% per unit increment above the salinity threshold. At 10 DAT, the plant height and stem diameter were not affected and only at 30 DAT were there significant differences due to ECsol, with a linear reduction of 3.98 and 5.27% (dS m−1)−1, respectively. While at 60 DAT, the salinity response for these variables was represented by a plateau followed by a linear decrease, with salinity thresholds of 5.18 and 5.01 dS m−1, and thereafter a relative decrease of 9.31 and 11.9% per unit increase in ECsol above the threshold, respectively, the values up to the salinity threshold being 0.87 m and 15.77 mm, respectively. The shoot dry mass up to 60 DAT reduced linearly with an increase in ECsol, but the plants under moderate salinity after acclimatization (90 DAT) surpassed the control treatment, and maximum dry mass accumulation was observed at an ECsol of 5.14 dS m−1. The results reveal that in hydroponic cultivation of “Biquinho” pepper under salt stress, growth is attenuated in the reproductive phase.