Assessing grapevine bud fruitfulness from different cultivars to assist early yield prediction

Abstract

The number of inflorescence primordia (IP) in compound buds has been previously reported to be closely related to the yield in the coming season. Primary bud necrosis (PBN) is a physiological disorder found in many commercial grapevine cultivars that results in the death of the primary bud and the loss of yield. During winter dormancy, microscopic bud dissection is used to assess bud fertility and therefore predict potential yield. This study aimed to assess the impact of primary bud necrosis on the development of IP and reproductive performance to improve early yield prediction. Canes were collected in July/2016 from Vitis vinifera L. cv. Shiraz, Cabernet Franc, Merlot, Sauvignon Blanc, Riesling and Semillon vines in South Australia. Bud dissection was performed to determine the number and transverse area of the inflorescence primordia (IP) found in the compound bud and the incidence of primary bud necrosis (PBN). At flowering, the width and length of inflorescences were measured and at harvest, bunches were collected and counted to assess bunch architecture. Compared to the secondary buds, more IPs were recorded in primary buds with larger average transverse area. Similarly, the inflorescence and bunches on primary shoots were larger than on secondary shoots. The transverse area of the IP had a strong linear relationship with the bunch weight and width at harvest (R² > 0.7). Therefore, the assessment of PBN and the transverse area of IP during bud dormancy may improve early yield prediction for the coming season.