Open AccessProduction, Survival, and Evaluation of Solid-Substrate Inocula of Penicillium oxalicum, a Biocontrol Agent Against Fusarium Wilt of Tomato
Author(s) -
Inmaculada Larena,
P. Melgarejo,
Antonieta De Cal
Publication year - 2002
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto.2002.92.8.863
Subject(s) - conidium , vermiculite , inoculation , fermentation , biology , horticulture , substrate (aquarium) , biological pest control , penicillium , fusarium oxysporum , food science , agronomy , botany , ecology
Production of conidia of Penicillium oxalicum (ATCC number pending), a biocontrol agent of Fusarium oxysporum f. sp. lycopersici, was tested in liquid and solid fermentation. P. oxalicum produced 250-fold more conidia in solid than in liquid fermentation at 30 days after inoculation of substrate. Solid fermentation was carried out in plastic bags (600 cm 3 ) especially designed for solid fermentation (VALMIC) containing 50 g of peat/vermiculite (PV) (1:1, wt/wt) with 40% moisture, sealed, sterilized, and then inoculated with 1 ml of a conidial suspension of P. oxalicum (10 5 conidia g -1 dry substrate), sealed again, and incubated in darkness at 20 to 25°C for 30 days. Addition of amendments to PV in a proportion of 0.5 (wt/wt) significantly increased conidial production of P. oxalicum. The best production was obtained on PV plus meal of cereal grains (barley) or leguminous seeds (lentil) (100-fold higher). Conidial production obtained after 5 days of inoculation was similar to that obtained at 30 days. However, viability of conidia produced in PV plus lentil meal was 35% higher than that of conidia produced in PV plus barley meal. Changes in proportions (1:1:0.5, wt/wt/wt; 1:1:1, wt/wt/wt; 1:0.5:0.5, wt/wt/wt; 1:1:0.5, vol/vol/vol) of components of the substrate (peat/vermiculite/lentil meal) did not enhance production or viability of conidia. Optimal initial moisture in the substrate was 30 to 40%. At lower moistures, significant reductions of production of conidia were observed, particularly at 10%. There was a general decline in the number of conidia in bags with time of storage at -80, -20, 4, and 25°C, or at room temperature (range from 30 to 15°C), with the highest decline occurring from 60 to 180 days. Conidial viability also was reduced with time, except for conidia stored at -20°C. Fresh conidia produced in solid fermentation system or those conidia stored at -20°C for 180 days reduced Fusarium wilt of tomato by 49 and 61%, respectively.