Articles
PARTIAL ROOTZONE DRYING. A NEW DEFICIT IRRIGATION STRATEGY FOR APPLE?
Article number
646_10
Pages
93 – 100
Language
English
Abstract
Partial Rootzone Drying (PRD) is a new deficit irrigation strategy that has recently been developed for grapevines in Australia.
We have been evaluating the PRD strategy for apples in New Zealand since 1995. In our early experiments with Gala and Fuji apples water savings of 30 % were achieved with no detrimental effects on fruit size, yield, and fruit quality (including post-harvest quality). In 1999, we set up a trial with Braeburn apples to compare the PRD technique to other types of water deficit.
Three deficit irrigation treatments (On/Off, PRD, and DI50) were compared to a well-watered Control.
All deficit treatments received 50 % of the irrigation volume applied to the Control, but differed in timing and/or placement of irrigation.
In the On/Off regime every second irrigation was omitted; with PRD water was applied to only half the trees rootzones; trees in the DI50 treatment received half the water compared to the Control.
Compared to the Control, the PRD and DI50 regime were watered at the same time while the On/Off and DI50 regime had the same wetted surface area.
Rainfall during the 1999/2000 season was about 40 % above the long-term average and only 320 mm of irrigation was applied in the Control (vs. 160 for the deficit treatments). The Control and PRD regime had a slightly higher yield and average fruit size than the On/Off and DI50 treatments.
However, these differences were not significant.
There was no treatment effect on fruit quality at harvest or after storage.
Rainfall during the 2000/2001 season was less than 40 % of the long-term average and 715 mm of irrigation was applied in the Control (vs. 357 mm in the deficit treatments). Compared to the Control, the On/Off and DI50 treatments reduced the yield.
Number and percentage of fruit reaching marketable size also was lower with On/Off and DI50. Within the deficit treatments the PRD regime was least affected.
We have been evaluating the PRD strategy for apples in New Zealand since 1995. In our early experiments with Gala and Fuji apples water savings of 30 % were achieved with no detrimental effects on fruit size, yield, and fruit quality (including post-harvest quality). In 1999, we set up a trial with Braeburn apples to compare the PRD technique to other types of water deficit.
Three deficit irrigation treatments (On/Off, PRD, and DI50) were compared to a well-watered Control.
All deficit treatments received 50 % of the irrigation volume applied to the Control, but differed in timing and/or placement of irrigation.
In the On/Off regime every second irrigation was omitted; with PRD water was applied to only half the trees rootzones; trees in the DI50 treatment received half the water compared to the Control.
Compared to the Control, the PRD and DI50 regime were watered at the same time while the On/Off and DI50 regime had the same wetted surface area.
Rainfall during the 1999/2000 season was about 40 % above the long-term average and only 320 mm of irrigation was applied in the Control (vs. 160 for the deficit treatments). The Control and PRD regime had a slightly higher yield and average fruit size than the On/Off and DI50 treatments.
However, these differences were not significant.
There was no treatment effect on fruit quality at harvest or after storage.
Rainfall during the 2000/2001 season was less than 40 % of the long-term average and 715 mm of irrigation was applied in the Control (vs. 357 mm in the deficit treatments). Compared to the Control, the On/Off and DI50 treatments reduced the yield.
Number and percentage of fruit reaching marketable size also was lower with On/Off and DI50. Within the deficit treatments the PRD regime was least affected.
Authors
H.W. Caspari, S. Neal, P. Alspach
Keywords
Malus sylvestris var. domestica, irrigation management, fruit size, fruit quality
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