Abstract
Raising vigorous and healthy potato seedlings from hybrid true potato seeds (TPS) under nursery conditions is critical for ease of field transplanting and seedling crop establishment as well as for a productive seed or ware crop. The use of plugs in seedling production systems is an important technique utilised to ease transplanting of seedlings and refine seedling production in seedling nurseries. While holding multiple advantages over other transplant production systems, multiple factors still influence the success of seedling production in plug trays. In this study, we explore the effects of substrate properties, type and volume; watering intervals; and nitrogen (N) and phosphorus (P) levels in nutrient solution on seedling vigour attributes in potato seedlings grown in plug trays under climate room conditions. The choice of substrate strongly influenced seedling attributes with more favourable performance in substrates with higher water holding capacity. Increasing plug volume also enhanced seedling attributes including dry biomass, leaf area and root to shoot ratios such that seedling performance was best in plug volumes > 22.5 cm 3 . A watering schedule with a high frequency was more favourable considering that longer intervals between watering events led to significant declines in seedling attributes. While the effects of increased P in solution were not conclusive, depending on genotype, increasing N in solution led to enhanced seedling attributes, with a nutrient sufficiency met at 200 mg L −1 N in solution. These findings further contribute to the current knowledge on factors influencing success in seedling production of potato seedlings developed from hybrid true potato seeds.