Comparsion of 11 maize hybrids resistance to the corn borer, Ostrinia nubilalis Hb.

Tavakkoli, Hojjat and Razamjou, Jabraeil and Nouri-Ganbalani, Gadir and Taghizadeh, Masud and Sharifi Zieva, Parviz (2009) Comparsion of 11 maize hybrids resistance to the corn borer, Ostrinia nubilalis Hb. Other thesis, University of Mohaghegh Ardabili.

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Abstract

In this research eleven hybrids of maize produced by seed and plant improvement institute of Karaj, were evaluated to determine resistant hybrids to the corn borer, Ostrinia nubilalis Hb. This study was carried out through two experiments (treated and nontreated) in randomized complete design experiment with three replications in Agricultural and Natural Resources Research Center of Moghan in 2008. Sampling was conducted to assess three mechanisms of resistance (antixenosis, antibiosis and tolerance). The study of antixenosis using two characteristics including number of egg mass and number of eggs per mass in second and third generation of this pest showed that there was a significant difference among hybrids (P<0/05). The hybrid K3640/3×MO17 had the highest number of egg mass while the hybrids ZP684, EXP1 and 20NS×K19 had the lowest number of egg mass. Antibiosis was assessed through the studying of vertical tunnel length, number of tunnels, number of larvae in stem, percentage of infested leaves, index of leaves infestation intensity (0-9) and number of larval tunnels per stem. The results showed that there was no significant difference among hybrids but the hybrids ZP684 and EXP1 had the lowest number of tunnel per stem and lowest larval tunnel per stem and the length of vertical tunnels was shortest on them as well as the lowest percentage of infested leaves and index of leaves infestation intensity (0-9) were found on these hybrids. The analyzing of percentage of stalk breakage and yield as indicators of tolerance evaluation showed that there was significant difference among hybrids (P<0/05). The percentage of stalk breakage was negatively and significantly correlated with yield and node diameter (P<0/05). Hence, comparison resistance or susceptibility of hybrids of maize to the corn borer indicated that BC666, S.C700 and S.C704 were the most susceptible hybrids with highest percentage of stalk breakage and low yield, and Hybrids EXP1 and ZP684 was the most resistant hybrids because of lowest percentage of stalk breakage and high yield.

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