Primary bud necrosis (PBN) as affected by cane diameter, node position and sampling date in grapevine ( Vitis vinifera L. 'Askari').

摘要

Low bud fruitfulness and percentage of bud burst are the biggest problem in some Iranian vineyards. This study was conducted to determine the correlation between the natural incidence of primary bud necrosis (PBN) with sampling date, cane diameter and bud position from 2005 to 2006. A factorial (3 factors) experiment in randomized complete blocks design with four replications was used. Compound buds at nodes 1 to 20 from mature canes with diameters of >10 mm and <10 mm were dissected, assessed for the presence of PBN. Results indicated that the effect of cane diameter, node position and date of sampling and interaction of diameter x node and node x time on incidence of PBN were significant. However, the highest percent of PBN (19.3%) was found on thicker canes and the lowest percent of PBN (7.74%) was observed on thinner canes. From the viewpoint of bud position, nodes from 1 to 5 and from 16 to 20 on canes had the highest (39.57%) and lowest (0.2%) %PBN, respectively. Also, the highest %PBN was observed in February (18.09%) and March (18.78%). The interaction of factors showed that there was a positive correlation between high shoot diameter and nodes proximal position on percent of PBN. To delay date sampling, incidence of PBN was higher in nodes proximal than distal. Our results recommended that fruitfulness should be estimated prior to pruning by dissection of a sample of buds, allowing growers to optimize yield by leaving the best combination of spur length and spur or cane numbers.