Infection of Curvularia gladioli on different gladiolus genotypes

Abstract

In this study the susceptibility of different genotypes of gladiolus (Gladiolus callianthus and the genotypes of G. grandiflorum T-704, Red Beauty, Tradehorn, Verônica, Amsterdam, Yester Gold, and Rose Friendship) was evaluated and correlated with the development of Curvularia gladioli infective structures. The plants were inoculated with a 3 x 10 4 conidial suspension of the pathogen, and the severity of infection was assessed eight days after inoculation. Leaf samples of G. callianthus and G. grandiflorum vars. Amsterdam, Red Beauty, and T-704 were collected 24 hours after inoculation. They were cleared and the rates of spore germination and appressorium formation of C. gladioli were quantified. G. grandiflorum vars. T-704 and Red Beauty were the most susceptible genotypes, followed by G. callianthus and G. grandiflorum var. Tradehorn. The remaining genotypes did not differentiate among them. No differences related to the conidial germination (93.5%) were found for the genotypes. However, the highest values for appressorium formation were observed for G. callianthus (66.5%) and G. grandiflorus var. Amsterdam (55.7%), and the lowest values were observed for T-704 (32.4%). Thus, appressorium formation of C. gladioli was higher on leaf surfaces of resistant genotypes. Key words: Gladiolus callianthus, Gladiolus grandiflorum, appressorium, curvularia leaf spot, flower bulb.Gladiolus is an ornamental plant of high economic value and occupies a prominent position in the global flower bulb industry (Benschop et al., 2010). Gladiolus is part of the Iridaceae family, together with Iris and Crocus (Meerow, 2012), and includes more than 260 species originating from Africa, Madagascar and Eurasia (Goldblatt et al., 2008). Gladiolus flowers of various colors are currently commercially available, and white and red flowers are preferred by Brazilian consumers (Tombolato et al., 2010).It is estimated that 60% of gladiolus corms in Brazil are intended for the production of cut flowers for the domestic market and the remaining 40% are exported, especially to Holland (Tombolato et al., 2010 (Magie, 1953;Baiswar et al., 2007; Shakir et al., 2008;Tombolato et al., 2010). The first report of Curvularia in gladiolus was in Florida in 1947(Magie, 1948. Since then, it has quickly become globally distributed (Boerema & Hamers, 1989). In Brazil, the curvularia leaf spot caused by C. gladioli Boerema & Hamers has recently been reported in G. grandiflorum vars. T-704 and Amsterdam. The symptomatic tissues showed leaf spots that were oval to circular, brown with dark edges, and surrounded by a yellow halo (Torres et al., 2013).Gladiolus breeding programs attempt to improve gladiolus features such as the color, number and shape of flowers, flowering capacity in winter, multiplication and resistance to foliar and corm diseases (Magie, 1960;Cantor, 2006). In Brazil, in addition to agronomic characteristics such as productivity and adaptability, breeding programs are focused on the search for genotypes that are resistant or tolerant to...

Occurrence of Diseases in Floricultural Crops in and around Jorhat, Assam

“…Conidia tapering slightly at ends ( Figure 22) ( Table 3). The results were in conformity with the Borah et al, 2019 study of Torres et al (2013), Riaz et al (2010).…”