Observed trends in winegrape maturity in Australia


L. B. Webb, CSIRO, PMB 1, Aspendale, Victoria 3195, Australia, tel. +613 9239 4549, fax +613 9239 4444, e-mail: leanne.webb@csiro.au


An extensive assessment of historical trends in winegrape maturity dates from vineyards located in geographically diverse winegrape growing regions in Australia has been undertaken. Records from 44 vineyard blocks, representing a range of varieties of Vitis vinifera L., were accessed. These comprise 33 short-term datasets (average 17 years in length) and 11 long-term datasets, ranging from 25 to 115 years in length (average 50 years). Time series of the day of the year grapes attain maturity were assessed. A trend to earlier maturity of winegrapes was observed in 43 of the 44 vineyard blocks. This trend was significant for six out of the 11 long-term blocks for the complete time period for which records were available. For the period 1993–2009, 35 of the 44 vineyard blocks assessed displayed a statistically significant trend to earlier maturity. The average advance in the phenology was dependent on the time period of observation, with a more rapid advance over more recent decades. Over the more recent 1993–2009 period, the average advance was 1.7 days year, whereas for the period 1985–2009 the rate of advance was 0.8 days yr−1 on average in the 10 long-term vineyard blocks assessed for cross-regional comparison. The trend to earlier maturity was associated with warming temperature trends for all of the blocks assessed in the study.