Early results from a study on irrigated potatoes show there might be room in some cases to cut back on scheduled watering.
Results from the first year of a three-year study have found that Russet Burbank potatoes appear to be quite tolerant to missing scheduled irrigations.
The study will look at how drought stress applied at different stages of tuber development affects potato quality and yield. The experiment was repeated at two planting dates to evaluate the effect of different environments on the response to drought.
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Four water-deficit treatments were applied starting in late June – unstressed control, early stress, late stress and combined early and late stress.
The unstressed treatment was representative of standard irrigation practices and was based on estimates of potential evapotranspiration and on tensiometer measurements taken at depths of 15 and 30 centimetres.
The first year of results showed that adding an additional 210-230 millilitres of water to the potato crop over the tuber bulking period from late June to early September (10 irrigations) had no appreciable effect on marketable yield of the potatoes. This was true for both planting dates.
Drought stress applied early or late in the tuber bulking stage also had no effect on marketable yield in the early-seeded crop. The late-seeded crop seemed more sensitive to differences in irrigation scheduling, the results suggesting that a delay in irrigation may boost yield.
In general, delaying seeding by two weeks resulted in a yield decline of about 15 percent over all drought stress treatments.
Don’t get too excited
Despite these results, don’t run out and turn off the water.
Researchers can’t explain the apparent insensitivity to stress of the potato crop in 1997. The events that caused it might not be repeated this year. Weather will have an obvious impact on the effects of the irrigation treatments.
Until more is known, potato growers should not change their irrigation program. But the results are intriguing and suggest there may be opportunities to use less water under certain conditions.
The experiment is being repeated in 1998 and will be expanded to include Shepody potato varieties.
The study was conducted at Agriculture Canada’s Brandon Research Centre in co-operation with the Manitoba Crop Diversification Centre. Funding is provided by the Manitoba Horticulture Productivity Enhancement Centre in partnership with Agriculture Canada.
