Genetic variation in silage nutritional composition traits of tropical maize germplasm evaluated across multiple environments

Abstract

Maize is the leading crop for silage production and a major energy source in animal diets globally. The production of low nutritional composition silage among livestock farmers is partly attributed to the absence of specialized stable silage tailored maize lines for hybrids development. There is scarcity of information related to genetic variation and plant—environmental relationship in silage nutritional composition traits among tropical maize germplasm, yet the demand for quality silage continues to grow due to the introduction and improvement in genetics of different animal breeds. Twenty maize genotypes were evaluated in five environments for silage nutritional composition traits mainly crude protein (CP), ether extract (EE), metabolizable energy (ME), neutral detergent fiber (NDF), acid detergent fiber (ADF), ash, dry matter (DM) and crude fiber (CF). pH was treated as the fermentation adequacy check. The combined analysis of variance revealed variations among environments (P < 0.001) for all the studied traits and genotypes differed significantly for DM, CF and ME (P < 0.001), and for EE and CP (P < 0.05). The G × E was significant for DM, CF, NDF, CP, EE and ME which reduced cross-environment predictability of genotype ranking and motivates within-environment or stability-based selection. Negative Pearson correlations were observed and varied accordingly among nutritional traits. Principal Component Analysis (PCA) explained 49.5% of the total variation among the nutritional traits where the first principal component (PC1) accounted for 26.0% of the variation and was strongly associated with CF, CP, DM and EE. The second principal component (PC2) explained 23.5% of the variation, and was primarily associated with ME, ash and fiber fractions that is NDF and ADF. The analysis of variance for Additive Main effects and Multiplicative Interaction (AMMI) model for CP, DM, CF and ME showed that, genotypes, environments and their interactions were highly significant. Genotypes NML88, CKDHL0089, POBLAC21C0 and POBLAC32C6 were stable across test environments and recommended only to be used as candidates for further silage nutritional evaluation trial across multiple environments in tropical region mainly Sub-Saharan Africa (SSA).