Effect of Dormancy-Breaking Techniques on Seedling Emergence and Growth of Cashew (Anacardium occidentale L.) in the Nursery

Cashew (Anacardium occidentale L.) seed propagation is frequently hampered by irregular and delayed seedling emergence, particularly in larger-seeded biotypes, yet systematic evaluation of dormancy-breaking techniques across nut size categories remains limited in the literature. The study evaluated pre-sowing dormancy-breaking treatments on nursery performance of three cashew nut biotypes. A 3 × 3 factorial experiment arranged in a Completely Randomized Design (CRD) was conducted at the Cocoa Research Institute of Nigeria (CRIN), Ibadan. Three dormancy-breaking treatments include control, 3% H₂O₂ immersion (16 hours) and mechanical scarification, were applied to three cashew biotypes (medium, large and extra-large). Emergence, morphological, biomass and root parameters were recorded and analyzed using ANOVA with Tukey's HSD test (p ≤ 0.05). Mechanical scarification consistently reduced days to emergence (13 days in extra-large seeds versus 20 days in the untreated control), achieved the highest cumulative emergence percentages across all biotypes (100% in medium; 77.50% in extra-large) and produced superior seedling height, leaf area, shoot biomass and root development indices. H₂O₂ treatment accelerated early emergence in large and extra-large seeds but exhibited phytotoxic effects in medium biotypes, suppressing final emergence percentage (51.00%) and seedling vigour. Extra-large seeds recorded the most severe physical dormancy under untreated conditions (49.00% final emergence at 28 days after sowing). Mechanical scarification is the most reliable and broadly applicable dormancy-breaking technique for cashew nursery production across the three biotypes, improving both emergence uniformity and seedling quality for field transplanting. Mechanical scarification is recommended for cashew nursery production across the three nut size biotypes.