Articles
ALTERNATE BEARING IN PISTACHIO AS A MASTING PHENOMENON: CONSTRUCTION COST OF REPRODUCTION VERSUS VEGETATIVE GROWTH AND STORAGE
Article number
470_47
Pages
340 – 348
Language
Abstract
The whole-tree effects of alternate bearing on the reproductive growth, vegetative growth, and carbohydrate storage in mature pistachio trees (scion: Pistacia vera L., rootstock: Pistacia atlantica Desf.) were examined.
Although it is generally accepted that the "off" year in pistachio may be used to accumulate carbohydrate reserves, it was found that starch and sugars from the "off" year equaled only 8% of the construction cost of the "on" year’s nut load.
Furthermore, "off" year growth of perennial woody tissue in the roots, trunk and branches (20.2 kg/tree), was 75% of the mass of nuts in "on" trees (26.4 kg/tree). When construction cost of wood and nuts is considered, "off" year woody tissue growth is 64% of "on" year nut growth.
Since previous studies have shown that leaf growth is generally 30% greater in "off" trees, we conclude that the overall "off" and "on" year biomass production in pistachio is similar.
Therefore, we suggest that the "off" year is not a period of substantial storage carbohydrate accumulation, but rather a switch in allocation from reproductive to vegetative growth.
This is consistent with ecologically based theories of the adaptive advantage of masting behavior, and it suggests that withholding water and fertilizer during the "off" year may not harm "on" year yield.
Although it is generally accepted that the "off" year in pistachio may be used to accumulate carbohydrate reserves, it was found that starch and sugars from the "off" year equaled only 8% of the construction cost of the "on" year’s nut load.
Furthermore, "off" year growth of perennial woody tissue in the roots, trunk and branches (20.2 kg/tree), was 75% of the mass of nuts in "on" trees (26.4 kg/tree). When construction cost of wood and nuts is considered, "off" year woody tissue growth is 64% of "on" year nut growth.
Since previous studies have shown that leaf growth is generally 30% greater in "off" trees, we conclude that the overall "off" and "on" year biomass production in pistachio is similar.
Therefore, we suggest that the "off" year is not a period of substantial storage carbohydrate accumulation, but rather a switch in allocation from reproductive to vegetative growth.
This is consistent with ecologically based theories of the adaptive advantage of masting behavior, and it suggests that withholding water and fertilizer during the "off" year may not harm "on" year yield.
Authors
M.T. Stevenson, K.A. Shackel
Keywords
carbohydrate reserves, wood growth, Pistacia vera, nuts, ecology, life history strategy
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