Physiological Response of Cape Gooseberry Seedlings to Two Organic Additives and Their Mixture under Inoculation with Fusarium oxysporum f. sp. physali

Abstract

<jats:p>Vascular wilt caused by <jats:italic>Fusarium oxysporum</jats:italic> f. sp. <jats:italic>physali</jats:italic> is the most limiting disease in cape gooseberry crops. The use of natural products such as organic additives is a promising alternative for management of this disease. The present study sought to evaluate the physiological response of cape gooseberry plants infected with this pathogen and treated with the organic additives chitosan, burned rice husks, or their mixture. The test was conducted under greenhouse conditions and soil was inoculated with <jats:italic>F. oxysporum</jats:italic> f. sp. <jats:italic>physali</jats:italic> strain Map5. Chitosan was applied to seeds and seedlings at the time of transplantation, whereas burned rice husk was incorporated into the soil in a 1:3 ratio. Plants inoculated and not inoculated with the pathogen were used as controls. The following variables were evaluated: area under the disease progress curve (AUDPC), leaf water potential, stomatal conductance (<jats:italic>g</jats:italic><jats:sub>S</jats:sub>), leaf area (LA), dry matter accumulation, photosynthetic pigment contents, proline synthesis, and lipid peroxidation estimation [malondialdehyde (MDA)]. The results showed that cape gooseberry plants with vascular wilt and treated with chitosan had higher <jats:italic>g</jats:italic><jats:sub>S</jats:sub>, leaf water potential, LA, dry matter accumulation, and proline content values. In addition, the levels of vascular wilt severity decreased in comparison with pathogen-inoculated controls. The results suggest that chitosan applications on cape gooseberry plants may be considered as an alternative in the integrated management of the disease in producing areas, because they can mitigate the negative effect of the pathogen on plant physiology.</jats:p>

Mixtures of Biological Control Agents and Organic Additives Improve Physiological Behavior in Cape Gooseberry Plants under Vascular Wilt Disease

“…Okorski et al [61] obtained similar responses with the application of a mixture of different BCAs (biological preparation of effective microorganisms such as lactic acid and photosynthetic bacteria and yeast), which also generated an increase in gas exchange parameters such as photosynthesis, g s, and transpiration in pea plants (Pisum sativum L.) with Fusarium oxysporum wilt symptoms. A previous study also indicated that Foph-infected cape gooseberry plants and treated with chitosan showed better gas exchange (g s ) and Ψ wf parameters compared to plants without chitosan [45].…”

“…The microorganisms selected for the mixtures were Trichoderma virens and Bacillus velezensis (formerly B. amyloliquefaciens) due to their biocontrol potential against plant pathogens [11,38]. Regarding organic additives, chitosan (Sigma Aldrich, St. Louis, MO, USA) and burnt rice husk were also selected due to their potential control of Foph observed in a previous study [45]. Eight groups of treatments were obtained for the development of the experiment: (i) cape gooseberry plants with no addition of BCAs or organic additives and inoculated with Foph (pathogenic control (Foph + )) or without it (absolute control (Foph − )); (ii) cape gooseberry plants with or without Foph inoculation and with the application of the mixture of BCAs (T. virens and B. velezensis (Mix)); (iii) cape gooseberry plants with or without Foph inoculation with the application of the mixture of BCAs and the addition of chitosan (MixChi) and (iv) cape gooseberry plants with or without Foph inoculation with application of the mixture of BCAs and the addition of burnt rice husk (MixRh).…”

“…Plants of treatments 1, 2, and 3 were established in substrate that contained a mixture of soil and rice husk at a 3:1 ratio (v/v), whereas burnt rice husk was incorporated into the soil at the time of transplantation obtaining a soil-husk substrate at a 3:1 ratio (v/v) in treatment 4. These substrate mixtures have been used in previous studies in which the individual effect of BCAs or organic additives on vascular wilt in cape gooseberry plants was compared [38,45]. Finally, the pathogen's absence in the soil used in the preparation of substrate mixtures was confirmed previously by the technique described by Park [94], by adding 100 mL of cool-molten galactose-nitrate agar (GNA) medium with 10 µg•mL −1 benomyl and 300 µg•mL −1 chloramphenicol to the soil sample.…”

“…Furthermore, this biopolymer has been reported for the control of F. oxysporum under different growing and media conditions because of its antimicrobial and biostimulant activities, and its capacity to promote resistance mechanisms in plants [43,44]. Finally, a previous study also showed that chitosan incorporation into the rhizosphere helped the physiology of plants infected with Foph [45].…”

“…In Colombia, one of the most limiting biotic agents in cape gooseberry crops is Foph, which is the species that causes vascular wilt, showing a wilt incidence greater than 50% in the production areas [54]. Alternatives based on biological control have become very important for the P. peruviana-Foph pathosystem in Colombia [11,38,45]. These studies have allowed selecting promising alternatives and knowing the plant responses to the individual use of BCAs such as T. virens or B. velezensis.…”