INTRODUCTION
Traditional seed systems in sub-Saharan Africa depend largely on farmer-saved sorghum seeds, which play a vital role in food security, seed sovereignty, and maintaining on-farm biodiversity in low-input farming systems. However, limited information exists on how stem rank (mainstem vs. tiller-derived) influences subsequent seed quality, seedling establishment, and yield performance. This study evaluated the interaction between genotype and stem rank harvesting source on subsequent physiological seed quality and field performance under traditional seed systems.
MATERIALS AND METHODS
Seeds were collected during the 2023/24 season from four sorghum types: two hybrids differing in tillering ability, one open-pollinated variety (OPV), and a landrace grown at the University of Limpopo Experimental Farm. A 4 × 3 factorial design tested the effects of cultivar and stem rank (mainstem, tillers 1–2). Seed viability and vigour were analyzed using R statistical software with an unbalanced two-way ANOVA under a completely randomized design (CRD). Post hoc mean separation was conducted using the Bonferroni–Sadik test at the 5% probability level via the agricolae package. Field performance was analyzed using a two-way ANOVA under a randomized complete block design (RCBD) in GenStat® Version 20, with mean comparisons performed using the Bonferroni test.
RESULTS
Germination exceeded 80% across all genotypes and stem ranks, with no significant differences (p < 0.05). However, mainstem and tiller 1 seeds exhibited superior membrane integrity (<25 µS·cm⁻¹·g⁻¹), metabolic activity, and seedling vigour, while tiller 2 seeds showed delayed maturation and reduced vigour, particularly in hybrid Mr. Buster. Field performance mirrored these trends, with yields above 3 t·ha⁻¹ but reduced yield in Mr. Buster tiller 2.
CONCLUSION
All seed sources maintained high viability and yield potential, but prioritizing mainstem, tiller 1 and tiller 2 seeds especially in resilient genotypes such as Macia, PAN606, and the landrace can sustain subsequent seed vigour and productivity in traditional sorghum seed systems across sub-Saharan Africa.
