Deficit irrigation of almond trees did not decrease yield

The use of strategies that ensure the most effective and efficient use of irrigation water is a significant contributor to the economic success of the Australian almond industry. An experiment to test such strategies was established in north-western Victoria, Australia. Five levels of irrigation were tested over three seasons: a fully irrigated control (100%), three levels of deficit irrigation (55, 70 and 85% of the control) applied as regulated deficits (RDI) for specific periods during the growing season, or sustained deficits (SDI) throughout the growing season, and a high irrigation level (120%). The 100% control was defined as the level of irrigation that met the treesRSQUO water requirements and was not different from 120% in any variable measured. The results showed that irrigating at 85% of full irrigation had no impact on individual kernel weight and yield, but irrigating at 70% or less decreased kernel yield regardless of strategy, except for SDI 70% in Season 3. In Season 3, trees with SDI 70% deficits produced a higher kernel yield than the trees receiving the same deficit as RDI. Water deficits tended to accelerate hull split in line with the level of deficit. Midday stem water potential was significantly more negative two to six weeks before harvest in the deficit treatments.