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
圣弗朗西斯科河中游谷地以其适配多用途葡萄种植的独特条件而闻名。用于榨汁的葡萄生产在此区域尚属新兴产业，当前学界对该生产系统的各组成环节的认知仍较为有限。本研究聚焦2017年与2018年上半年的生产周期，旨在探究巴西伯南布哥州佩特罗利纳市贝贝多鲁试验场/巴西农业研究公司半干旱分部（Embrapa Semiárido）试验田中，整形方式与砧木对灌溉栽培的‘BRS Magna’葡萄品质及抗氧化活性的影响。
本试验供试处理包括3种整形方式：棚架（overhead trellis）、琴形架（lyre）与垂直新梢定位架（vertical shoot positioning, VSP），以及2种砧木：‘IAC 572’与‘IAC 766’；试验采用随机区组设计，设置时间亚亚区组，共4次重复。
总体而言，试验指标的响应情况受整形方式、砧木品种及生产周期共同调控，上述因素共同决定了葡萄的各项特异性状。2018年上半年生产周期所产葡萄具有更高的花青素含量、总可提取多酚含量与抗氧化活性，且其响应特征因整形方式和砧木品种而异。采用棚架整形并嫁接‘IAC 572’砧木的植株，其浆果的总可提取多酚积累量与抗氧化活性均更高。采用垂直新梢定位架（VSP）整形的植株，浆果的糖含量、黄色类黄酮含量与花青素含量均有所提升；而琴形架整形方式则可获得更高的果穗质量。