Breeding maize as biogas substrate in Central Europe: I. Quantitative-genetic parameters for testcross performance

Abstract

Biofuels have gained importance recently and the use of maize biomass as substrate in biogas plants for production of methane has increased tremendously in Germany. The objectives of our research were to (1) estimate variance components and heritability for different traits relevant to biogas production in testcrosses (TCs) of maize, (2) study correlations among traits, and (3) discuss strategies to breed maize as a substrate for biogas fermenters. We evaluated 570 TCs of 285 diverse dent maize lines crossed with two flint single-cross testers in six environments. Data were recorded on agronomic and quality traits, including dry matter yield (DMY), methane fermentation yield (MFY), and methane yield (MY), the product of DMY and MFY, as the main target trait. Estimates of variance components showed general combining ability (GCA) to be the major source of variation. Estimates of heritability exceeded 0.67 for all traits and were even much greater in most instances. Methane yield was perfectly correlated with DMY but not with MFY, indicating that variation in MY is primarily determined by DMY. Further, DMY had a larger heritability and coefficient of genetic variation than MFY. Hence, for improving MY, selection should primarily focus on DMY rather than MFY. Further, maize breeding for biogas production may diverge from that for forage production because in the former case, quality traits seem to be of much lower importance.

Silage Maize and Sugar Beet for Biogas Production in Rotations and Continuous Cultivation: Dry Matter and Estimated Methane Yield

“…Our finding of a strong influence of DM yield on estimated methane yield (Table 1, Figure 1) was confirmed by Graß et al [7], Grieder et al [19], Mayer et al [27], and Sieling et al [13]. Consequently, we recognized highest estimated methane yield of silage maize in Aiterhofen when cultivated in the rotation (catch crop mustard -) silage maize-winter wheat-winter wheat (9388 Nm 3¨h a´1) and lowest in this rotation in Harste (6458 Nm 3¨h a´1).…”

“…The yield level of silage maize in our trials was slightly higher compared to results of Graß et al [7], Grieder et al [19], and Herrmann et al [20], who reported a silage maize DM yield between 19.1 and 21.8 t¨ha´1¨a´1 but not exclusively for highly-productive sites. Our mean DM yield of sugar beet root in crop rotations (Aiterhofen and Harste: 17.0-23.0 t¨ha´1¨a´1) was in the lower range in comparison to results of Starke and Hoffmann [14] who detected DM yield of different varieties between 17 and 27 t¨ha´1¨a´1.…”

“…These results were in a similar range to those of Amon et al [18] who reported possible methane yield of about 7500-10,200 Nm 3¨h a´1 when silage maize was cultivated under suitable climatic conditions. Lower methane yield of silage maize was observed by Grieder et al [19] as 3990-7120 Nm 3¨h a´1. Estimated methane yield of sugar beet root in our study was lower (3729-7964 Nm 3 ha´1; lowest values gained under continuous cultivation) compared to silage maize due to lower annual DM yield.…”

Breeding maize as biogas substrate in Central Europe: II. Quantitative-genetic parameters for inbred lines and correlations with testcross performance

“…Therefore, inbred lines are evaluated in crosses with different testers for their testcross performance (TP). In a companion study based on TP, Grieder et al (2011b) examined different traits in a broad germplasm collection and discussed their results with respect to breeding of biogas maize. They observed a preponderance of general combining ability (GCA) over specific combining ability (SCA) effects for agronomic as well as quality traits.…”

“…Estimates of r g between LP and TP depend on the predominant type of gene action (Hallauer and Miranda 1988;Mihaljevic et al 2005;Smith 1986) and, therefore, vary for different traits. For forage maize, correlations between LP and TP for DMY, days to silking (DTS) and various quality traits ranged from moderate to strong (Argillier et al 1995;Gurrath et al 1991;Kreps et al 1998;Seitz et al 1992). Thus, estimates of r g between LP and TP for novel traits like MFY and MY, which are important for biogas maize, are needed to develop optimum breeding strategies.…”