Sustainable management of the main two Maltese indigenous grape varieties for winemaking

Abstract

Ġellewża and Girgentina, the main two Maltese indigenous grape varieties that are used for winemaking, are grown in small parcels of land with an average size just over 0.1 ha. Policies and regulations that influence the sector have been set up and this increased the need for studies to understand the current management practices and how can they be more sustainable. Through interviews with 30 growers of the indigenous grape varieties it was found that most vines are trained as bush vines and cane pruned with 2 or 3 canes with about 5 to 10 buds in each. Nutrition is mainly given in the form of artificial fertilizer or organic pellets, but the timing is varied. Growers also have varied strategies for plant protection, mainly based on the use of sulfur and copper sulfate, and systemic fungicides. 14 growers also used insecticides, but the use of herbicides was not found to be common. Only 12 growers irrigated their vines and the water quality was found to be different from one location to another, with very high water conductivity, chlorides, and nitrates observed in some locations, mainly those close to Għajn Rihana. Data obtained from sugar levels and yield of 2010, 2011, and 2012 harvests were analysed. Temperature, precipitation and wind speed data for those three seasons were also reviewed to understand the trends along the viticulture season. For both varieties, there was no significant correlation observed between yield and sugar levels in most seasons. The brix was not significantly different from one season to another in most scenarios considered but the yield for 2012 was found to be significantly higher from that of the two other seasons, most probably due to weather conditions. The average yield for Ġellewża was higher than the average yield for Girgentina in every season. PCA analysis showed that the brix and yield data cannot be distinguished by location of vineyard. A list of recommendations was presented to ensure that the management practices are improved and therefore prove that sustainability is the way forward for Maltese vineyards and winemaking.