近红外高光谱成像技术检测成熟期酿酒葡萄果皮的花色苷含量

【目的】运用高光谱成像技术检测成熟期酿酒葡萄果皮的花色苷含量。【方法】利用900~1 700 nm近红外高光谱成像和多元回归模型对多品种酿酒葡萄成熟期不同阶段果皮花色苷含量进行预测建模。采集成熟期4~5个阶段的6个品种共75组酿酒葡萄样本的高光谱图像,运用不同预处理方法对光谱数据进行处理。基于主成分分析(PCA)和连续投影法(SPA)降维,将化学方法测量结果作为花色苷含量的参考值,采用支持向量回归(SVR)建立花色苷含量预测模型。【结果】SPA-SVR模型性能优于其他模型,其预测决定系数(R_p~2)为0.869 1,均方根误差(RMSEp)为0.135 9。【结论】将近红外高光谱成像技术应用于多品种成熟期酿酒葡萄果皮的花色苷含量的快速无损检测具有良好的可行性。     

Inhibition of Botrytis cinerea growth and suppression of botrytis bunch rot in grapes using chitosan

Chitosan inhibited growth of Botrytis cinerea in liquid culture and suppressed grey mould on detached grapevine leaves and bunch rot in commercial winegrapes. Germination of B. cinerea was completely inhibited in malt extract broth containing chitosan at concentrations greater than 0·125 g L^?1. However, treated conidia were able to infect detached Chardonnay leaves and pathogenicity was not affected, even after incubation for 24 h in chitosan at 10 g L^?1. When added after conidial germination, chitosan inhibited B. cinerea growth and induced morphological changes suggestive of possible curative activity. The effective concentration of chitosan that reduced mycelial growth by 50% (EC₅₀) was 0·06 g L^?1. As a foliar treatment, chitosan protected detached Chardonnay leaves against B. cinerea and reduced lesion diameter by up to 85% compared with untreated controls. Peroxidase and phenylalanine ammonia‐lyase activities were also induced in treated leaves. In vineyard studies, Chardonnay winegrapes exhibited 7·4% botrytis bunch rot severity at harvest in 2007 after treatment with an integrated programme that included chitosan sprays from bunch closure until 2 weeks preharvest, compared with 15·5% in untreated controls and 5·9% with fungicide treatment. In the following season, botrytis bunch rot severity was 44% in untreated Chardonnay at harvest and the integrated programme (21%) was less effective than fungicides (13·8%). However, in Sauvignon blanc winegrapes, the integrated and the fungicide programme each reduced botrytis bunch rot severity to 4% and were significantly different from the untreated control (11·5%). This study provides evidence that suppression of botrytis in winegrapes by chitosan involves direct and indirect modes of action.     

5个红色酿酒葡萄品种花色苷组成差异分析

以5个红色酿酒葡萄品种(‘美乐’‘赤霞珠’‘马尔贝克’‘小味尔多’‘马瑟兰’)为材料,利用高效液相色谱-质谱法(HPLC-MS)检测各品种成熟期果皮的花色苷,并利用主成分分析方法对5个红色酿酒葡萄品种的花色苷组成进行差异分析。结果表明,‘美乐’的甲基花青素类花色苷的所有比例较高,‘赤霞珠’中的花翠素类和未酰化类花色苷的所有比例最高,‘马尔贝克’的特征花色苷是花翠素-3-香豆酰葡萄糖苷和甲基花翠素-3-香豆酰葡萄糖苷,‘小味尔多’含有较高的甲基花翠素类和花翠素-3-乙酰葡萄糖苷。另外,‘马瑟兰’含有较高的香豆酰类花色苷,尤其是二甲花翠素-3-反式香豆酰葡萄糖苷,且未检测到花青素类花色苷。