Effect of Seedbed on Emergence and Establishment From Surface Sown and Direct Drilled Seed of Eucalyptus Spp. And Dodonaea Viscosa.

Abstract

In some areas the increase of woody plants is a problem whereas in others, the lack of regeneration is viewed with a similar degree of concern. The experiments described in this paper were an attempt to further understand factors affecting regeneration of woody plants. The effect of seedbed on the emergence and survival of hopbush (Dodonaea viscosa ssp. angustissima) and on several species of Eucalyptus was evaluated at two sites in the Central West of New South Wales. Seed was sown in two springs, two summers and two autumns from 1990 to 1992 and seedlings monitored for 12 months after sowing. Seedbeds compared were prepared by cultivation, scalping, burning, applying herbicide (glyphosate) and mowinglgrazing (control). Following failure of surface sowing in spring 1990 and summer 1990191 due to poor seasonal conditions, all subsequent experiments included direct drilled controls. Emergents were recorded in most treatments in the four succeeding seasons but hopbush and eucalypts responded differently to treatments. Numbers of hopbush emergents and seedlings after 12 months were consistently higher following direct drilling into scalped seedbeds. In contrast, the maximum number of eucalypt emergents was not consistently associated with any seedbed type, though emergence was generally higher following direct drilling. However, higher numbers of eucalypt seedlings were present in scalped plots after 12 months. It was concluded that weed control following emergence was the main effect of seedbed preparation on the number of eucalypt seedlings present after 12 months. Though this also applied to hopbush. seedbeds which provided the opportunity of seed burial enhanced emergence. This was believed to be due to the breaking of seed dormancy.