Morphological Characterization of Guinea Grass (Megathyrsus maximus) Across a Ploidy Series in Semi-arid Conditions of Central India

Guinea grass (Megathyrsus maximus) is a vital tropical forage crop characterized by extensive genetic variability, particularly in ploidy levels. This study evaluated the morphological and growth characteristics of guinea grass across eight ploidy series (3x–9x, 11x) and a reference genotype (SRP75) to understand the impact of ploidy on phenotypic expression. Ploidy plants were collected from the IGFRI experimental field and grown in pots with three replications. Quantitative data were analyzed using a Completely Randomized Design (CRD) at a 5% level of significance. Morphological descriptors such as growth habit, leaf hairiness, node and leaf base coloration, leaf orientation, and leaf color were recorded, along with quantitative traits including plant height, tiller number and diameter, leaf and node count, internode length, leaf dimensions, spike length, and number of florets per spikelet. All accessions displayed perennial growth. Notable variation was observed in traits like hairiness, pigmentation, and leaf orientation, indicating ploidy-dependent morphological shifts. Intermediate ploidy levels, particularly 5x, 6x, and 8x, demonstrated superior vegetative growth and reproductive traits, including greater plant height (112 to 139 cm), tiller robustness, and spike length (22 to 28 cm), suggesting enhanced biomass and seed production potential. Conversely, very low (3x) ploidy levels showed reduced growth (63 cm plant height and 73 florets/spike) and vigor. These findings underscore the influence of ploidy on phenotypic traits and provide valuable insights for breeding programs targeting high-yielding and stress-resilient guinea grass genotypes.