engleski

Estimation of combinig ability for resistance of maize inbred lines to Fusarium ear rot

Fusarium verticillioides is one of the most common maize pathogens in Croatia. It infects maize (Zea mays L.) ears and kernels, resulting in Fusarium ear rot disease, reduced grain yields, and contamination of grain with mycotoxins. Breeding for resistance to Fusarium ear rot represents the most efficient way to fight this disease. The aim of this study was to estimate combining ability for resistance to Fusarium ear rot of 7 Bc Institute’s maize inbred lines selected upon the results of screening tests. Inbred line IL1 was chosen as potential source of resistance whereas other six inbred lines had various levels of susceptibility/resistance. Field experiment comprised of 42 diallel test crosses (F1s and reciprocals) was set up as RCBD with three replicates and conducted in Rugvica 2013 and 2014. In this trial two techniques of artificial infection with inoculum of F. verticillioides were used, together with the uninfected control treatment. The first inoculation technique (M1) was performed with modified needle attached to a veterinary syringe, while the second (M2) was performed according to Reid and Hamilton (1996). Disease severity was evaluated on harvested ears using the scale from 1 to 7 defined by Reid and Zhu (2005). The diallel analysis was performed by using Griffing (1956) Method 3 model 1 and performed for the three inoculation conditions each experimental year separately. Among test crosses significant differences were found in 2013 for all three infection conditions and in 2014 for the M1 disease technique only. In 2013 mean disease severity rates ranged from 1.0 to 1.5 for control, from 1.1 to 3.9 for M1 and from 1.7 to 2.6 for M2, while in 2014 they ranged from 1.0 to 1.7 for control, from 1.3 to 3.9 for M1 and from 1.6 to 2.5 for M2. Significant GCA effects were in 2013 found for M1 and M2 and in 2014 for control and M1. Significant SCA effects were in 2013 found for control and M2 and in 2014 for M2 only. Significant effects due to reciprocals were found for two inoculation techniques and control only in 2013. In both experimental years IL1 (potential source of resistance) had the best GCA values for resistance to Fusarium ear rot under both conditions of artificial infection while the test crosses with the best SCA and reciprocal effects were inconsistent among the three infection conditions and two experimental years. The M1 method of artificial infection was more efficient than M2 since it resulted in higher mean and wider range of the disease ratings.

Fusarium ear rot; maize; mycotoxins

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