Miquel Pascual

Canopy management in rainfed vineyards (cv. Tempranillo) for optimising water use and enhancing wine quality

BACKGROUND Rainfed viticulture, mainly in semi-arid environments, is limited by environmental variability, particularly precipitation and its seasonal distribution, and soil water availability, thus ultimately determining the final quality of grape and wine. Studies on the feasibility of practices such as canopy management to adapt plant growth and yield to soil water availability open up possibilities to preserve wine quality and reinforce the characteristics of the terroir. RESULTS Principal components analysis was used to identify the relationships between a large set of variables, including soil, plant, canopy management, and wine characteristics. Canopy management was found to have a predominant influence on plant response to soil water by modifying plant water status, changing the amino acid profile in berries and, concomitantly, altering the sensorial attributes of the wine obtained. CONCLUSIONS Grapevine canopy management strategies, such as reiterate shoot trimming to restrict growth during early phases, are effective in adapting plant response to soil water availability. Such strategies affect berry and wine quality, mainly the amino acid profile and sensorial attributes of the wine, without changing yield or grape harvest quality control parameters. Also, in such conditions, nitrogen does not make a significant contribution to grapevine growth or yield or to grape quality.

Relationship between polyphenol oxidase activity and nutrition, maturity and quality parameters in flat peach

BACKGROUND Polyphenol oxidase (PPO) is one of the main factors that determine postharvest stability and therefore commercial possibilities of peach orchards. Since the activity of this enzyme depends on several variables of different nature, stating the relationships among them is essential to manage crop inputs so as to achieve the desired quality. RESULTS Multivariate projection techniques were used to identify these relationships throughout on-tree maturation in flat peach samples that had received different fertilisation doses, but harvested in equal conditions of soluble solids, fruit weight, diameter, firmness and skin and flesh colour. A relatively low fertilisation dose that was enough to avoid any lack of nutrients provided the lowest crop yield, but also with the lowest PPO activity. Fruit N/Ca ratio turned out to be a better indicator of PPO activity than isolated nitrogen or calcium content. Nutrient analyses on leaves did not have strong correlations with any significant parameter. The most useful variables to predict PPO activity before harvest were fruit firmness and skin colour, both of them read at the onset of on-tree maturation. CONCLUSION High fertilisation doses resulted in greater yields, but also with higher PPO activity, which is detrimental for the commercial chances of the fruit.