CO430, CO431 and CO432 corn inbred lines

Abstract

Breeding Methods and Pedigree CO430, CO431 and CO432 were developed by the Eastern Cereal and Oilseed Research Centre, Agriculture and AgriFood Canada, Ottawa, ON, and are all lines derived from a synthetic population made up from five commercial hybrids (Pride K127, Funks G4106, Renk RK21, Northrup King NK9060, and First Line FL1656), which were found, during a routine screening of commercial hybrids in 1989, to possess moderate to high levels of resistance to ear rot. CO430 to CO432 were derived from individual ears of the second cycle of selection of the synthetic by continual inbreeding with selection for silk resistance to F. graminearum at the S 2 , S 3 , S 4 and S 7 generations using the silk channel screening protocol outlined by Reid et al. (1996). Only those lines in which greater than 50% of the fusarium-inoculated plants exhibited no visual symptoms of infection were advanced to the next generation. During development, lines were also selected on the basis of combining ability and adaptation with testing at the S 3 , S 4 and S 7 generations to testers of different heterotic groups. Subsequent studies on the original five hybrids of the synthetic indicate that Pride K127 and Funks G4106 (now known as Enerfeast) were the major sources of resistance. PerformanceIn 1997, the final yield performance evaluation of CO430, CO431 and CO432 was conducted (Table 1) at Ottawa, ON (2750-2800 CHUs) in trials consisting of two-row plots with four replications. Three commercial hybrids (Pioneer 3905, Pioneer 3893 and NK 0565) were used as checks. The testers were all single-cross hybrids: CO328 × CO309 is hybrid of two inbreds derived from Pride 5; CO390 × 99N19 is a Lancaster type tester; and, A641Ht × CM105 is a Reid, B14 type tester. CO432 has slightly better combining ability than the other two inbreds.All three inbreds were rated as possessing excellent emergence and seedling vigour in Ottawa, ON.Other Characteristics CO430, CO431 and CO432 all have wedge-shaped kernels and red cobs. CO430 kernels are red-orange in colour and intermediate between dent and flint. CO431's kernels are also red-orange but are flint-like. CO432's kernels are yellow-orange and flint-like. CO431 is suitable for use as a female or male parent with a seed parent ear yield of approximately 82 g while CO430 and CO432 are best suited as a male parent with a seed parent ear yields of approximately 71 g and 65 g, respectively. All three inbreds take 71-79 d for both 50% tasselling and silking, compared with CO255 which takes 67-68 d and B73 with 83 d. The ears of CO430 are cylindrical, 13 cm in length, 3.8 cm in diameter, have 16 kernel rows, and have up to 6 cm of husk covering the tip of the ear. CO430 is 151-163 cm in height with 14-16 leaves,

Breeding for resistance to ear rots caused by Fusarium spp. in maize – a review

“…Visual identification of a pathogen is often not possible: with mixed infections, atypical symptoms can occur. In inoculated trials, the breeder is determining which species is the predominant one; in trials where multiple species are inoculated at the same time, the environmental conditions after inoculation determine which species will predominate (Reid et al. 2001a,b).…”

“…In this study, DON levels increased rapidly such that by 2 weeks after silking concentrations were above 1 mg/kg. Reid et al. (2001a,b, 2003) have released eight maize inbreds (CO387, CO388, CO389, CO430, CO431, CO432, CO433, CO441) specifically bred for increased resistance to GER using both silk channel and kernel inoculation techniques.…”

“…Both silk channel and kernel resistance were investigated: the selection for kernel resistance was more effective, and the resistance was more stable. Reid et al. (2001a,b, 2003) used modified pedigree selection to develop eight inbreds with improved GER resistance, some with high levels of both silk and kernel resistance.…”

“…Reid (1999) collected germplasms from around the world (adapted and unadapted) with moderate to high resistance to various ear pathogens, but no mention was made of how the inbreds were produced. However, as indicated in Reid et al. (2001a,b, 2003), inbreds were inoculated every generation in their development with the exception of few generation advances that were performed in off‐season winter nurseries.…”

Long Chain Alkanes in Silk Extracts of Maize Genotypes with Varying Resistance to Fusarium graminearum

“…During a routine screening of maize germplasm in the late 1980s, CO272 was found to possess moderate resistance to silk infection by F. graminearum. This inbred as well as some other sources of resistance have been used in the AAFC breeding program to develop newer inbreds with improved resistance to silk infection (10,11). The objective of the current study was to expand previous work (2) to examine the relationship between longchain alkane content of silks and F. graminearum resistance in CO272, some of the newer AAFC ear rot resistant releases, and a selection of inbreds and hybrids varying in resistance to F. graminearum.…”