Evaluation of cornstarch and sagú on in vitro growth of Sclerotium rolfsii

Abstract

The high cost of agar commonly employed in the preparation of culture media has become prohibitive in Venezuela. This situation requires searching for alternative sources of national origin to facilitate the process of agricultural research. This research was conducted with the aim of evaluating the dose of cornstarch and sagú as solidifying agents to replace agar in potato dextrose agar (PDA) culture medium. Cornstarch obtained from the commercial product Maizina Americana®, was evaluated at a dose of 50, 75, 100 and 125 g/l, and sagú starch obtained from the tuber Maranta sp. at doses of 60, 70, 80 and 90g/l. For all doses was used 15 g of dextrose, 500 cc of the decoction of 200 g of potatoes and 20 g of sucrose per liter of culture medium. For each of the tests, a control treatment with PDA alone was used. Discs were removed from the periphery of the colony from PDA plates with pure isolation of S. rolfsii and were planted in the Petri dishes used to test doses of cornstarch and sagú. The radial growth of the fungus was quantified at 24, 48 and 72 h after plating. A completely randomized statistical design was used, with five treatments, four replications and the experimental unit consisted of four Petri dishes. According to the results obtained, the most promising cornstarch dose was 125 g/l and, and sagú, was 60 g/l. Both may be employed as alternative sources for solidifying culture media used in laboratory conditions, particularly for S. rolfsii