NOVEL SEED TREATMENT WITH RHIZOBACTERIA ON HOT PEPPER (Capsicum annuum L.): ITS EFFECTS ON RHIZOBACTERIA AND SEED STORABILITY, PLANT GROWTH, AND INCIDENCE OF PHYTOPHTHORA BLIGHT
Ilyas, S.1, Madyasari, I.1, Zakia, A.1, Budiman, C.1 and Manohara, D.2
1Department of Agronomy and Horticulture, Faculty of Agriculture, Bogor Agricultural University, Jl. Meranti, IPB Darmaga Campus, Bogor 16680, Indonesia
2Indonesian Research Institute for Spice and Medicinal Crops, Ministry of Agriculture. Jl. Tentara Pelajar No.3, Bogor 16111, Indonesia
Contact: Satriyas Ilyas, email@example.com
Novel seed treatments, biopriming and seed coating, using rhizobacteria have been developed to overcome phytophthora blight in hot pepper. The disease is caused by Phytophthora capsici, a seed- and soil-borne fungal pathogen. Effects of biopriming on controlling phytophthora blight (PB) and improving plant growth in the greenhouse (experiment 1), and effects of biopriming and seed coating in the field (experiment 2) were evaluated. Effects of both treatments were also evaluated on the viability of seed and rhizobacteria during storage (experiment 3). All experiments were carried out on hot pepper seed cv. Laris which is susceptible to P. capsici. Results of experiment 1, bioprimed for 24h with F2B1 or combination of E1+F2B1 isolates improved plant height 14-21 days after transplanting (DAT), and reduced PB from 13.3% in positive control (seeds were soaked in potato dextrose broth without rhizobacteria, and the resulted plants were inoculated with P. capsici inoculum soil) down to 6.1% at 5 days after inoculation (DAI) of P. capsici inoculum soil. Seed treatment with metalaxyl was not effective to control PB. While in experiment 1 all rhizobacteria used were isolated from healthy hot pepper plants among the PB infected ones, in Experiment 2 and 3 only the best (E1+F2B1) was used and rhizobacteria isolates from Piper nigrum were also included. Biopriming with E1+F2B1 increased plant height compared to negative control at 25 DAT. Seed coating plus E1+F2B1 increased leaf number at 18 and 25 DAT compared to negative and positive controls. Seed coating plus ST116B or E1+F2B1 or biopriming with E1+F2B1 reduced disease incidence 20-22.5% compared to metalaxyl (100%) at 17 DAI. Biopriming and seed coating with rhizobacteria maintained seed viability (79 - 89%) for 24 weeks stored at 27–30⁰C compared to metalaxyl (54.3%). Biopriming with E1+F2B1 isolates resulted the highest seed vigor index after 24 weeks of storage. Population of rhizobacteria in seed tissue decreased in bioprimed seeds from 105-107 cfu g-1 to 104 cfu g-1 after being stored for 24 weeks. Population of rhizobacteria in coated seeds was only 104 cfu g-1 at start of storage and remained the same at the end of storage period.