Investigation on susceptibility corn hybrids to corn smut under condition of natural infection and artificial inoculation
2002
Jalali,Sadegh | Sabzi,Mohammad Hossein
In order to susceb~ble evaluation of selectivel com lines (30 lines) to common smut (Ustilago maydis) and identified resistance or tolerable lines, an experiment was conducted for two years (1999-2000) by using a spilit plots exprimental design with four replication. Main factor was methods of infection with 3 levels including: natural infection, artifical unwounded leaf whorl infection and cut cob infection. Sub factor was different corn lines. For natural infection after seedling stage a mixture of animal maniure and telios pores (2g1kg) of the fungi seater among planted rows. For artificial infection, an inoculum, consisting of mixed sporidial at 10 6 cells per milliliter was applied to unwounded leaf whorl one week before tasseling stage, in other method 1.5 - 2 em of cob was removed with pruning shears and 300 of sporides (106 spore/ml) was injected into the cut cob. The cut cob injection , method showed the highest infection among com lines (more than 90%). The disease severity scale (0-7) used to for record smut severity on ears of com lines, that showed difffered significantly among corn lines and categories in four groups., Group 1: Consist of thiee lines without infection (Immiun), group2: Consist of two lines with T (Trace) or highly tolerable ., group 3: Consist of 15 lines from moderately tolerable to moderately suscebtible (scale 1-2.25) and group 4, Consist of 10 lines from highly suscebtible to moderately suscebtible (scale 6.75-3) Therfor, ear-injection inoculation methods should be further evaluated for usefulness in producing smutted ears for disease screening.
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