Leaf mineral nutrients composition and primary bud necrosis disorder in fruiting and de-fruited ‘Askari’ grapevine

Primary bud necrosis (PBN) of grapevine, which is a physiological disorder, seriously decreases the fruit yield of vineyards. This research was carried out to determine the effects of mineral deprivation on increasing the incidence of PBN in ‘Askari’ table grapes in Sisakht region of Southwest of Iran. For this purpose, the changes of mineral elements in leaves and PBN percentage were estimated on both fruiting and de-fruited ‘Askari’ vines. The experiment followed a factorial experiment in a randomized completely block design consisting of 10 × 2 (10 sampling dates × 2 treatments (fruited and de-fruited)) and four replicates was conducted. Eighty leaf samples were collected from vine clusters located in four blocks of commercial vineyard every 10 days starting 40 days after bud break (DAB) until 130 DAB. PBN was first studied by a hand lens and then by a microscope after dissecting the buds. The results showed that the initial symptoms of PBN appeared at 60 DAB. The PBN disorder progresses as bud development proceeds, with the higher percentage of PBN being observed in de-fruited vines than fruiting ones. In both fruiting and de-fruited vines at 60 DAB, the amount of iron content was close to the critical deficiency level whiles the concentration of elements such as Zn, B and Mn, was below the critical range. Furthermore, with increasing the concentration of Zn, B and Mn in leaves, PBN percentage significantly decreased.