Bell pepper production under saline stress and fertigation with different K+/Ca2+ ratios in a protected environment

ABSTRACT. Bell peppers are sensitive to salinity; therefore, it is necessary to find alternatives to reduce saline stress. An experiment was conducted in a greenhouse at Federal Rural University of the Semi-Arid Region, in Mossoró, Rio Grande do Norte State, Brazil, to evaluate the effects of salinity and K+/Ca2+ ratios on bell pepper production. The experimental design consisted of randomized blocks in a 5 x 4 factorial scheme with four replicates, corresponding to five K+/Ca2+ ratios (F1 = 3.3/1, F2 = 2.8/1, F3 = 2.2/1, F4 = 1.8/1, and F5 = 1.5/1) and four salinity levels in the nutrient solution using NaCl (1.75, 3.25, 4.75, and 6.25 dS m-1). The following parameters were evaluated: the number of fruits (total, marketable and unmarketable), the mean weight of fruits (marketable and unmarketable), fruit production (total, marketable and percentage of marketable fruits) and a salinity tolerance index. Generally, nutrient solution enrichment with K+ or Ca2+ did not cause significant increments in bell pepper yield. The fertigation treatments F2, F3, and F5 led to a higher bell pepper tolerance to salinity, allowing waters with higher salt concentrations to be used without causing a reduction in the yield.

摘要。甜椒对盐胁迫较为敏感，因此亟需探索缓解盐胁迫的可行方案。本试验于巴西北里约格朗德州莫索罗市半干旱地区联邦农村大学的温室内开展，旨在评估营养液盐度与K+/Ca2+比例对甜椒产量的影响。试验采用5×4因子设计的随机区组方案，设置4次重复，包含5个K+/Ca2+比例梯度（F1=3.3/1、F2=2.8/1、F3=2.2/1、F4=1.8/1、F5=1.5/1）以及4个以氯化钠（NaCl）配置的营养液盐度梯度（1.75、3.25、4.75、6.25 dS·m⁻¹）。本试验测定指标包括：果实数量（总果数、商品果数、非商品果数）、果实平均重量（商品果与非商品果单果重）、果实产量（总产量、商品果产量及商品果占比）以及盐胁迫耐受指数。研究结果显示，总体而言，提升营养液中K+或Ca2+浓度并未显著提升甜椒总产量。但F2、F3、F5三个水肥灌溉处理可显著提高甜椒的盐胁迫耐受能力，允许使用更高盐浓度的灌溉水体而不造成产量下降。