Climate change ready varieties and management technologies that reduce greenhouse gas emissions in the vineyard

Abstract

This project successfully established a new field trial to evaluate new scion and rootstock combinations under different plant densities. Narrow row, high density plantings were established to compare to the typical Australian wide row, low density plantings. The scion-rootstock combinations were chosen to investigate the effect on plant vigour and yield. To reduce inputs and minimise greenhouse gas (GHG) production from tractor usage the trial was planted with mildew resistant varieties that do not require regular spray application. A new dwarf scion selection was included in the trial to evaluate its potential to be grown over several seasons without the need for pruning and thus contribute to reduced management costs and reduced GHG production. Further evaluation of the trial over several seasons will determine the potential cost savings to industry and reduction in vineyard GHG of the new scion-rootstock combinations that might be achieved under high and low density plantings.

Summary

It has been stated that global intensification of agriculture will be required to not only address the challenges of climate change but also the limited availability of land and water resources (The Royal Society 2009). A study in California found that the largest known contributor to greenhouse gases (GHGs) in the vineyard was fuel usage (Carlisle et al. 2010) to manage plant growth and control diseases such as mildews. Intensification of vineyard production by increasing vine density was investigated in Australia by McCarthy in 1992 and encouraging results were obtained but the disadvantage was managing vine vigour.

This report describes the establishment of a new experimental trial site to re-examine the potential for sustainable intensification of Australian viticulture to achieve lower inputs and higher outputs per unit land. Since 1992, new management techniques have been developed and new grapevine selections produced that may be better suited to low input intensive viticulture.

CSIRO has bred new grapevine selections suited to the warm-hot Australian conditions. The scion selections are resistant to powdery and downy mildews. Some of these new scions (no-prune) require little or no canopy management or winter pruning. In addition, CSIRO has bred new rootstocks tolerant or resistant to root pathogens (phylloxera and root-knot nematodes) and these rootstocks may modify scion vigour and water use efficiency.

The objective of this project was to establish a new experimental field site partitioned into low and high density plots. The experimental design included the planting of four scion selections (two white and two red berry selections) either on own roots or grafted onto three different rootstocks. Data on vineyard input costs, plant vigour, water use and berry quality were collected.

The experimental vineyard was successfully established although it took longer than expected due to the limited supply of plant material for grafting and as a result, no wine was produced in the final year. The details of the data collected are described in the report with a number of promising outcomes highlighted below.

The study found that no mildew infections were observed on the plants during the term of the trial even though no spraying for mildews was done on site. Not having to spray for mildews is a considerable cost saving in terms of labour, chemicals and GHG production from tractors. Other benefits included reduced exposure of vineyard staff to chemicals and surrounding areas to spray drift lessening potential health risks and reducing the social impacts in the peri-urban fringe/rural areas.

The no-prune scion selections performed as expected and no pruning or canopy management was required for these selections either on own roots or grafted onto rootstocks. Pruning and labour costs associated with pruning have been reported to be a significant industry cost (30% of operating expenditure). Also of interest was that the analysis of berry composition indicated that the no-prune vines had similar composition to berries from normal vines, suggesting that wine made from the grapes of no-prune vines should have similar attributes to normal vines.

Preliminary data suggested that rootstocks might have an effect on vine vigour and some berry components but the major finding was that rootstocks did not markedly change the vigour (measured indirectly by LAI and visual observation) of the no-prune vines. It was found that under the same irrigation regime, 54% less water was used per plant in the high density plot compared to the low density plot. This suggested that the water use efficiency might be greater in high density blocks, however, further study is required over several seasons with different irrigation treatments to investigate water use efficiency in relation to yield and wine quality attributes.

The study found that a number of changes to vineyard management would occur if future research at the site demonstrated significant advantages to adopting mildew resistant no-prune vines or higher density plantings. Irrespective of plant density, the use of mildew resistant vines would provide considerable benefits to vineyard management by reducing the need for labour, chemicals and tractor usage. A future scenario with adoption of no-prune vines would allow vines to be grown under high density conditions and require little or no canopy management or pruning, further reducing management costs.

This project developed a unique trial site to evaluate new scion and rootstock material and to investigate management methods that reduce costs and inputs (sprays, labour, water and pruning). Further research is required over several seasons to fully investigate the potential benefits of the plant selections and management treatments at this trial site. The preliminary results in this report are very encouraging but multi-seasonal data from mature vines are required to fully assess the advantages and disadvantages of the experimental treatments in terms of management costs, water use efficiency, yield per hectare and fruit and wine quality. One disadvantage of a high density block in Australia will be the establishment cost which was found to be 1.34 times more expensive in this study due mostly to the additional posts and vines. This initial cost will have to be measured against the operating costs over the life of a high density vineyard and potential returns.

Sustainable intensification of Australian viticulture while maintaining yield and wine quality is challenging, but continued use of this experimental site for research will provide important information on what might be achievable and provides a demonstration to the Australian wine industry of the advantages, disadvantages and challenges of different vineyard intensification scenarios under predicted climate scenarios of increased temperatures and reduced water availability.