Scientists in the U.S. state of California have made promosing research advances to help peach farmers reduce water useage without negatively impacting yields or quality.

Soil scientist Dong Wang examines leaves of peach trees that underwent postharvest deficit irrigation. Photo: Peggy Greb

The Agriculture Research Service (ARS) team studied the effects of deficit irrigation on a 4-acre plot of Lady Crimson trees, with the goal of reducing water needs for the San Joaquin Valley's 25,000 acres of peach orchards.

Peach production in the valley currently faces the difficult task of watering trees the most during postharvest when temperatures are high and demand is at its greatest. In recent years, snow melt and wells have not been able to sufficiently satisfy the faults of irrigation, according to the United States Department of Agriculture (USDA).

To ease demand, researchers Dong Wang and James E. Ayars from the San Joaquin Valley Agricultural Sciences Center are finding ways to reduce water use in peak months.

Wang explained the team's attempt to reduce water use at select stages of growth and correct water stress at other times of the year, such as in winter and spring.

“With peach trees, the issue is that over two-thirds of the water is applied after harvest. We’re looking for ways to reduce that,” Wang said in a media release.

Between June and September, trees were watered with either 25 percent of the normal amount, 50 percent of the normal amount or 100 percent. The team controlled for rainfall and implemented standard fertilization, pruning and fruit thinning.

Three types of irrigation systems were used in the study: microspray, subsurface drip irrigation and furrow.

The researchers found at 25% watering, fruit showed more deformities with lower yield and quality. At 50%, however, they found a minimum effect on yield and quality. Trees also required less pruning and maintenance due to stunted plant growth.

“Most of the water savings we saw occurred during the hottest part of the year, when demand for water is highest, so there’s a real potential for savings,” Ayars said.

The study has been submitted for publication to HortScience.

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