Yield and quality have always been locked in battle with each other, and the lament has always been, `Wines aren't what they used to be'. Edward Hyams (Dionysus, A Social History of Wine, Sidgwick & Jackson, 1965) traces the demise of ancient Rome's most famous wine, Falernian (immortalised by Horace and Martial). `The primacy of Falernian lasted three centuries, but under economic pressure, the owners were tempted to increase output at the expense of quality ... not much later it was just one of a score of good, reliable wines.' The British wine?writers of the early twentieth century, led by Professor George Saintsbury, were clearly convinced we would never again see wines of the longevity, the power and the quality of the golden years before phylloxera.

There is at once truth and mendacity in these laments; what many observers fail to recognise is that wine and wine style are dynamic and ever-changing commodities which necessarily have to be produced in the social and economic conditions of their time. Equally necessarily, wine and wine style must meet their economic and aesthetic expectations.

In Roman times vineyards were planted at a density of 50 000 vines per hectare and were tended by hand; by the middle of thenineteenth century, as horses became commonplace, the density was 10 000 to 15 000, in modern European viticulture the density is usually 4000 to 8000; in Australasia it is 1500 to 3000, allowing for large tractors, mechanical harvesters and so on (with a few hectares here and there at European density). Yet yields per hectare have increased rather than decreased, which means, of course, that the yield per vine has increased dramatically. This is a pattern strikingly apparent in Australia over the course of this century, and which has rapidly gathered momentum since 1950.

It is a vivid indication of the massive changes in viticultural practice which have taken place in Australia (and also in New Zealand, where yields have been even higher but where similar trends are evident). However, before looking at the principal causes (and implications) of the changes, there are two lesser aspects which need to be recognised.

First, while nominal vine density per hectare has not changed greatly (if anything, it will have decreased), improved selection of vine stock has largely eliminated the once-common occurrence of barren (non-fruiting) vines, and gaps (where vines have died and not been replaced) are no longer tolerated because of economic factors. Secondly, extraction of juice from the grapes, recovery of lees, and general winery efficiency have increased the effective yield per tonne of grapes.

The trend to ever higher yields is strongly in evidence, and notwithstanding the theoretical constraints of appellation control in Europe, the same trend is evident there. Indeed Germany has experienced yield increase on a scale similar to that of Australia, and many see this as one of the most important factors in the dramatic decline in the reputation (and marketability) of German wine.

The impetus in Germany came partly through the development of early-ripening higher-yielding varieties (hitis vinifera hybrid crosses), partly through selection of vigorous rootstocks on to which the vin fera scions are grafted, partly through clonal selection within varieties, partly through improved disease and pest control, and partly through increased use of herbicides and fertilisers. Clonal selection and rootstock selection have played a similar role in Australasia over the past 25 years, and are going to continue to play an important role.

Next, irrigation has ceased to be the dirty word it once was. It took Australian vignerons and commentators a long time to realise the fundamental difference between the climate of, for example, Bordeaux and Burgundy on the one hand, and the vast majority of Australian and New Zealand regions on the other. In France, not only does 45 to 55 per cent of the rainfall occur during the growing season, but it tends to be spread fairly evenly over this season. In Australasia, most regions receive inadequate rain between the end of November and the end of March to keep the vine in balance. A vine which is suffering from excessive moisturestress (that is, lack of moisture) will produce fruit which is chemically out of balance (high pH and low acid) and almost certainly lacking in flavour.

The flexibility which irrigation allows has meant larger vines with more vegetative growth. This in turn has led to the development of trellises and of canopy management systems as far removed from the traditional single?wire low trellis as a model T Ford is from a Lamborghini. In Australasia most of the research and development came from two academics: Peter Clingeleffer of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Dr Richard Smart (who has since moved emphatically into commerce as a Flying Viticulturist, consulting to wine companies around the world). Their paths have taken sharply divergent courses (Smart favouring highly complex trellis design and canopy manipulation, Clingeleffer allowing the vine to make all its own adjustments by eliminating pruning and canopy manipulation altogether), but the end aim has been much the same. That aim has been to produce a vine with the appropriate balance between new growth (canes and leaves) and crop levels, and to ensure in so doing that the grapes and the buds which will produce next season's growth receive sufficient sunlight. Suffice it to say here that most of these developments have led (once again) to increased crop levels, even if there has been a concomitant increase in quality from improved trellis design and better canopy management techniques.

For the best part of a decade now it has been fashionable to talk about `making wine in the vineyard' and to prophesy that the next quantum leap in improvement in wine quality will occur in the vineyard rather than in the winery. While there is no resiling from that view, there is a subtle groundswell of opinion across France, America and Australasia that we have become altogether too clever in our selection, breeding and manipulation of the vine, and that far more attention should be paid to limiting yield and to improving grape quality.

One of the most obvious ways of achieving this is to reverse the trend to bigger and more vigorous vines. Europe has a different regime (although similar concerns), but in Australasia one method of achieving this would be the selection of rootstocks which suppress vigour and yield, rather than enhance it. Another means is to pay far more attention to the taste of the wine in clonal selection trials, rather than to select purely on the basis of yield and chemical composition, which is the traditional tendency. Some growers, too, are sharply cutting back the use of fertilisers and synthetic fungicides in a conscious endeavour to turn back the clock.