Quality and antioxidant potential of ‘BRS Magna’ grapes harvested in the first half of the year under different training systems and rootstocks in a tropical region

ABSTRACT The Submedium São Francisco Valley is renowned for its particular conditions for cultivating grapes for different uses. The production of grapes for juice is relatively recent, and thus, knowledge is still limited on components of the production system. The aim of this study was to characterize the quality and antioxidant activity of ‘BRS Magna’ grapes in irrigated crops of the Submedium São Francisco River Valley under the influence of training systems and rootstocks, in production cycles of the first half of the year. The experiment was conducted in the Experimental Field of Bebedouro/Embrapa Semiárido, in Petrolina, Pernambuco, Brazil. The following were studied: overhead trellis, lyre, and vertical shoot positioning (VSP) systems and rootstocks ‘IAC 572’ and ‘IAC 766’, in the production cycles corresponding to the first halves of 2017 and 2018. Experimental design was in randomized blocks, with sub-subplots through time and four replicates. Overall, responses depended on training systems, rootstocks, and production cycles, which determined specific traits of the grapes. Production in the first half of 2018 was characterized by high anthocyanin contents, high total extractable polyphenols, and higher antioxidant activity, and responses were differentiated according to training system and rootstock. Plants trained to overhead trellis and grafted on ‘IAC 572’ had higher accumulation of total extractable polyphenols and antioxidant activity in berries. Plants trained to VSP had increased sugar, yellow flavonoid, and anthocyanin contents in berries while lyre training system led to higher bunch mass.摘要 圣弗朗西斯科河谷中下游（Submedium São Francisco Valley）以其适配多种用途葡萄种植的独特条件而闻名。用于榨汁的葡萄种植起步相对较晚，因此当前对其生产系统各环节的认知仍较为有限。本研究旨在探究圣弗朗西斯科河谷中下游灌溉种植条件下，‘BRS Magna’葡萄在上半年生产周期中的品质与抗氧化活性，及其受整枝方式与砧木的影响。本试验于巴西伯南布哥州佩特罗利纳市的贝贝多鲁/巴西农牧业研究公司半干旱分部（Embrapa Semiárido）试验田开展。试验研究了3种整枝方式：棚架式（overhead trellis）、琴形整枝（lyre）与垂直新梢定位架（vertical shoot positioning, VSP），以及2种砧木：‘IAC 572’与‘IAC 766’，并以2017年和2018年的上半年作为生产周期进行试验。试验采用随机区组设计，以时间作为亚亚区处理，设置4次重复。总体而言，葡萄的各项指标响应受整枝方式、砧木及生产周期影响，这些因素共同决定了葡萄的特定性状。2018年上半年的葡萄生产中，浆果表现出较高的花青素含量、总可提取多酚含量以及更强的抗氧化活性，且其指标响应因整枝方式与砧木不同而存在差异。采用棚架式整枝且以‘IAC 572’为砧木的植株，其浆果的总可提取多酚积累量与抗氧化活性更高；采用垂直新梢定位架整枝的植株，浆果的糖含量、黄色类黄酮含量与花青素含量均有所提升；而琴形整枝则可带来更高的果穗质量。