Seedbank longevity of kiwifruit, Actinidia chinensis var. deliciosa

Abstract

Kiwifruit (Actinidia spp.) is an important horticultural crop, but unmanaged self-propagation results in ‘wild kiwifruit’, a serious environmental weed that can harbour pests and diseases, threatening New Zealand’s kiwifruit industry. Seed is the main dispersal mechanism for wild kiwifruit, and its longevity impacts weed-management planning. To determine the persistence of wild kiwifruit seed in a seed bank, we buried 800 kiwifruit seeds (A. chinensis var. deliciosa ‘Hayward’) in fine-mesh bags at a single depth (5–10 cm) in well-draining sandy loam under simulated field conditions. Bags were retrieved annually for three years and seed germination rates assessed in the last two years. Germination declined markedly between 24 and 36 months: seeds buried for 24 months showed high germination (80%), whereas those buried for 36 months exhibited very low germination (1%). This sharp decline indicates that wild green kiwifruit forms a short-lived seedbank, with most seeds losing viability between two and three years. These findings support the practical feasibility of eradicating wild kiwifruit populations following plant removal, provided seed rain is prevented. Also, these findings reinforce the importance of continued vigilance by industry and land managers, in covering fruit bins, using bird netting, and removing or mulching old vines, to minimise seed escape and reinvasion risk. Our results strengthen confidence that local eradication of wild kiwifruit is achievable with sustained management.