ABSTRACT

Cotton seed germination and root development in seedlings is promoted in the presence of Brotomax (up to 0.1% v/v). Ten days after planting, increased taproot and lateral root growth was observed compared to controls. Thirty-day-old Brotomax-treated seedlings exhibited increased root development with lateral roots more enlarged than that seen in control seedlings. Accompanying this effect, the chlorophyll content of leaves from Brotomax-treated plants (2.7 mg/g fw) was higher than that in leaves from control plants (2 mg/g fw). Moreover, the phenolic content of the leaves and stems of treated plants (0.98 mg/100 g fw and 1.04 mg/ 100 g fw, respectively) was higher than that measured in the leaves and stems of control plants (0.89 mg/100 g fw and 0.97 mg/100 g fw, respectively).

Twenty-five-day-old seedlings infected with Fusarium oxysporum and treated with Brotomax showed increased total chlorophyll content and lower phenolic compound content than similarly infected but untreated control plants. Moreover, in F. oxysporum-infected seedlings, treatment with Brotomax reduced the level of ethylene production compared to that seen in control seedlings. Finally, PCR experiments showed that the advance of F. oxysporum in seedlings treated with Brotomax was lower than that observed in control seedlings. These results demonstrate that Brotomax increases cotton seedling tolerance to infection by vascular fungi such as F. oxysporum.