Fruiting Cuttings: Revised Method for Producing Test Plants of Grapevine Cultivars

Abstract

The inflorescences of hardwood cuttings of the grapevine usually shrivel and die soon after bud burst. The original method developed by Mullins (1) for producing small fruiting cuttings for use as experimental plants has now been improved. Cuttings are rooted in a heated container (26°C at bases of cuttings) in a cold room (4°C). Buds remain dormant. After four weeks the rooted cuttings are transferred to the glasshouse or to growth rooms (27°C day and 22°C night, 16 h photoperiods, irradiance 60 Wm^-2). At bud burst, leaves basal and adjacent to inflorescences are removed as soon as accessible and the shoot tip is excised. These treatments promote inflorescence growth. A lateral shoot is permitted to grow from an axillary bud of one of the defoliated nodes on the main axis. When four to six leaves have been produced the lateral shoot is tipped and disbudded. Development of the bunch to maturity is supported by the foliage of the lateral shoot. Véraison occurs at approximately 12 weeks from bud burst and ripe fruit is produced in 16 to 18 weeks. The ripe berries of test plants are about half normal size but seed is highly germinable. A list is given of cultivars which are easy, intermediate or difficult to propagate as test plants.