Evaluation of plant growth-promoting rhizobacteria for biological control of pythium root rot of cucumbers grown in rockwool and effects on yield

Abstract

Three strains of Pseudomonasfluorescens (63-49, 63-28, and 15), one strain of Pseudomonas corrugata (13) and one strain of Serratia plymuthica (R1GC4) were tested on rockwool-grown cucumbers for their ability to reduce Pythium root-rot caused by Pythium aphanidermatum. These strains were previously selected for biocontrol ability from collections of >4000 bacteria. Strains 63-49 and 63-28 were tested on cucumber plants grown in rockwool in two replicated Pythium-inoculated trials conducted in British Columbia (B.C). Another inoculated, replicated trial was conducted in Quebec with all five strains. Cucumber yields (fruit number and weight) were measured over a ten-week harvest period. Strain 63-49 caused an early promotion of plant growth and increased cucumber yields at early harvests. No measurable effect of Pythium inoculation on disease development was observed in the Quebec trial, due to unfavourable cool weather. However, 63-49 significantly increased the total number of cucumbers (12%) and cucumber weight (18%), compared to the non-treated control. Strains 13, 15 and R1GC4 slightly increased the cumulative cucumber yields, but strain 63-28 had no effect. In the B.C. trial, inoculation with P. aphanidermatum reduced the number and weight of cucumbers by 27%. Treatments of Pythium-inoculated cucumbers with 63-49 significantly increased fruit number and weight by 18 %, compared to the Pythium-inoculated control. Strain 63-28 increased the cumulative number of cucumbers over time, compared to the Pythium-inoculated control, but the increase was less than with 63-49. The use of Pseudomonas spp. in rockwool-grown cucumbers can increase yields, both in the presence and absence of Pythium root rot, and with variable seasonal conditions and disease pressures.

Effects of nutrition and Bacillus amyloliquefaciens on tomato (Solanum lycopersicum, L.) growing in perlite

“…Studies related to PGPR in hydroponics have mainly concentrated on their antagonism of harmful microorganisms. It is reported that pseudomonad PGPRs can increase the fresh weight of cucumber fruits by 18% (McCullagh et al, 1996). One strain of Bacillus subtilis increased cucumber yield by 14% compared to Pythium aphanidermatum-inoculated controls (Utkhede et al, 1999).…”

Plant Beneficial Microbes and Their Application in Plant Biotechnology

“…Moreover, their application has recently expanded both in forestry and in phytoremediation of contaminated soils. Strains belonging to the genera Azospirillum (Okon & Labandera-Gonzalez, 1994;Okon & Itzigshon, 1995;Dobbelaere et al, 2001), Bacillus (Reddy & Rahe, 1989;Kokalis-Bourelle et al, 2002;Kokalis-Burelle et al, 2006) and Pseudomonas (McCullaugh et al, 1996;Meyer et al, 2010) have been used in experimental tests on a wide range of economically important crops.…”

Screening and Identification of Harmful and Beneficial Microorganisms Associated with Replanting Disease in Rhizosphere Soil of Pseudostellariae heterophylla

“…Burkholderia sp1 had antagonistic ability to Fusarium isolated from sick plants of P. heterophylla, and no pathogenicity to plantlet of P. heterophylla. Various antagonistic microorganisms have different biological control mechanisms, and someone has several mechanisms already known (Mccullagh et al, 1996;De Curtis et al, 2010;Nally et al, 2013). The mechanisms involve antibiotic effect, space and nutrition competition, parasitism and inducing systemic resistance of plant, etc (Inbar et al, 1996;Boopathi and Sankara, 1999;Orwa et al, 2002;Gong et al, 2006).…”