Reciprocal differences for forage traits in single and three‐way crosses of maize

Abstract

Eleven flint inbreds of maize were crossed with 11 dent inbreds according to a balanced incomplete factorial mating design to produce 66 single crosses (2W) in both reciprocal forms. Additionally, six threeway crosses (3W) were also produced in both reciprocal forms. These hybrids were evaluated for 11 forage yield and quality traits in 1983 and 1984 at three sites in Germany. Highly significant reciprocal diiferences were observed for nine traits in the 2W. The respective variance component estimates amounted to 2-33% of the variance component due to crosses. On average, flint x dent 2W had lower dry-matter content (DMC) than dent x flint 2W and a 1 % greater dry-matter yield (DMY) of forage. Three-way crosses produced on singles exhibited greater DMC (3%) and DMY (5%) of the ear, metabolizable energy content (MEC) of stover (1%), and DMC and DMY of forage (2%) than their reciprocal forms produced on lines. Based on this study, because of their minor importance, routine testing for reciprocal difl"erences among 2W hybrids is not recommended.Differences between reciprocal crosses have been reported by several investigators for various agronomic characters in different types of maize {Zea mays L.) materials for grain usage (review: see Melchinger et al. 1985). However, there is Httle consensus in the literature concerning the relative importance and systematic exploitation of these effects in practical breeding programmes. This is because reciprocal differences were generally not consistent across environments and did not have a uniform sign for all hybrids tested between two germplasm groups.Most of the earlier studies on reciprocal differences in maize were conducted with North American dent material. Only a few reports have been published on reciprocal differences for crosses among flint and dent inbreds adapted to the cooler climatic conditions in central Europe. Mann et al. (1981) reported signiflcant reciprocal differences for dry-matter yield of grain and stover, and suggested that they should be considered in applied breeding programmes. For interpool crosses, both Mann and Pollmer (1981) and Melchinger et al. (1985) found greater grain yield for hybrids produced on flint inbreds ( = seed parent) as compared with their reciprocal crosses produced on dent inbreds. For three-way crosses, Schnell and Singh (1978) observed sizeable reciprocal differences to the advantage of hybrids produced on single-cross seed parents as compared with their reciprocal forms produced on the parental inbred.All the above-mentioned studies investigated reciprocal differences of grain traits or of stover traits at grain maturity.Given that most of the maize grown in central Europe is cultivated for forage use, information about reciprocal differences for forage maize harvested at silage maturity is of great interest to breeders. The objectives of this study were: 1. To gather information about the importance of reciprocal differences in early maturing single and three-way crosses adapted to the climatic conditions of central Eu...

Mapping reciprocal effects and interactions with plant density stress in Zea mays L.

“…In a reciprocal cross, the same two parents are used, but their maternal and paternal roles are reversed. Differences between reciprocal crosses have been reported by several investigators for various agronomic characters in different types of maize materials for grain Melchinger et al, 1985) and silage usage (Seitz et al, 1995). Perhaps the most compelling evidence for reciprocal differences was obtained by Schnell and Singh (1978) working with three-way crosses, who observed sizeable reciprocal differences to the advantage of hybrids produced on the single-cross seed parents as compared with their reciprocal forms produced on the parent inbred.…”

“…Maize geneticists and breeders have recognized reciprocal effects as one source of genetic variability Seitz et al, 1995). Reciprocal effects may account for a large portion of the genetic variance in certain forms of resistance to insect feeding (Dhliwayo et al, 2005).…”