Evaluation of the Effect of Four Bacterial Isolates on the Plant Growth Promoting and the Reduction of Dry Rot of Potatoes

Abstract

The purpose of the following study is to evaluate the potential of four bacterial antagonists to reduce the development of the Fusarium dry rot and evaluate their role in growth promotion efficacy (plant height, fresh weight and dry weight) of the potato. After the screening in vitro, four antagonistic strains caused an inhibition of the fungi with a diameter greater than 27 mm, namely Fr43, Fr52, F101 of Pseudomons sp gender, and F31 of Acinetobacter gender. These strains were selected to study their effect in vivo. The treatment of tubers by successive immersions in the spores and in the bacterial suspensions showed the ability of the latter to protect the tubers during the storage. Concerning the growth promotion, all the applied antagonistic isolates exhibit a significant difference compared to the control. Consequently, the Fr43 strain is the most active. It has a height of 110.17cm, a fresh weight of 100,77cm and a dry weight of 44.27cm with a respective correspondence of 52.53%, 60.71 and 25.31% of the test GPE%. For the reduction of the Disease incidence, the isolate Fr43 also demonstrated a significant reduction in the incidence of the disease with 15.3%, which corresponds to a significant effectiveness of biological control of up to 79.92% against Fusarium oxysporum. On the contrary, the isolate F101 has the lowest value of the effectiveness of biological control versus control which can reach only 15.7%. Consequently, the isolates Fr43, Fr52 and F31 have a potential use not only in the bio-protection of potato but also in the integrated management of Fusarium wilt. They are also considered as PGPR.