Elicitores de resistência no controle de fusarium verticillioides em feijão fava

Abstract

The butter bean (Phaseolus lunatus L.) is an important source of nutrients in human nutrition, available in the form of dried or green beans, and it holds significant commercial value. Plant productivity is directly related to the genetic, physiological, physical, and sanitary characteristics of the seeds. Seed-transmitted pathogens pose a direct threat to production, with Fusarium verticillioides being a notable culprit. This pathogen causes damage under field and storage conditions and produces substances harmful to living organisms. Using alternative products for plant disease management helps prevent pathogens from becoming resistant and reduces contamination to humans and animals. Thus, the use of resistance elicitors is a promising alternative to chemical pesticides. The objective of this study was to evaluate the efficiency of resistance elicitors in controlling F. verticillioides in butter bean cultivars. The experiments were conducted at the Phytopathology Laboratory affiliated with the Federal University of Paraíba in Areia, PB. The elicitors used included Potassium Phosphite (3 mL L-1 ), Potassium Silicate (7 mL L-1 ), Bugram® (1g L-1 ), Potassium Phosphite (1.50 mL-1 ) + Potassium Silicate (3.5 mL-1 ), Potassium Phosphite (1.50 mL-1 ) + Bugram® (0.05g L-1 ), the fungicide Azoxystrobin (400 mL há-1 ), and the control group (untreated). In vitro tests assessed the mycelial growth and spore production of the pathogen under the described treatments. For the in vivo test, the following varieties of butter beans were used: Roxinha, Cara larga, Orelha de vó, Caramelo, and Cearense. The seeds were treated and inoculated with the pathogen at a concentration of 1 x 105 . Various parameters were analyzed, including plant length, stem diameter, dry mass of the aerial part, root volume, and dry root mass. Additionally, measurements were taken for initial fluorescence (F0), maximum fluorescence (Fm), variable fluorescence (Fv = Fm - F0), the Fv/F0 ratio, and the quantum yield of photosystem II (Fv/Fm). Chlorophyll levels (a, b, and total) were also assessed, along with the infection rate.The experimental design was completely randomized, following an 8 × 5 factorial scheme (eight treatments vs. five butter bean varieties), with four replications. Potassium phosphite and potassium phosphite + Bugram were the most effective in inhibiting mycelial growth, and all treatments successfully inhibited spore production. Each treatment demonstrated potential in reducing the infection rate in butter bean plants when seeds were treated, indicating their viability for controlling F. verticillioides. The elicitors positively influenced aerial and root length, dry mass of the aerial part and roots, leaf count, root volume, and chlorophyll content. Overall, the elicitors efficiently inhibited the mycelial growth and spore production of F. verticillioides, leading to a reduced infection rate across the varieties. Positive impacts on plant physiology and increased photochemical efficiency were observed in butter bean varieties treated with these elicitors.