Effects of doubled atmospheric CO2 concentration on apple trees III. Carbohydrate production

摘要

Two year old apple (Malus domestica Borkh. cv. 'Golden Delicious') trees on 'M9' were exposed to ambient (350 +/- 10ppm) and doubled (700 +/- 10ppm) atmospheric CO2 for 120 d in growth chambers situated in an apple orchard. The elevated ambient CO2 concentration increased carbohydrate production of apple trees. Both content and accumulation of non-structural carbohydrates, particularly starch and sucrose, rose in all organs of the trees under the doubled ambient CO2 condition. Relative distribution of non-structural carbohydrates within the trees rose in leaves, shoots, and roots, but declined in stems due to the long-term atmospheric CO2 enrichment. Carbohydrate proportions and starch/ sucrose ratio in different organs of the trees varied in line with the duration of the experiment. When compared with 350ppm CO2-treated trees, those grown at 700ppm CO2 increased non-structural carbohydrate-production efficiency of leaves by 48 % and 32 % in the first and the second 60 d of the CO2 treatments, respectively. Long-term atmospheric CO2 enrichment constantly improved non-structural carbohydrate-production efficiency of the apple trees, especially starch-production efficiency. A further increase of the global atmospheric CO2 concentration in the future will promote carbohydrate production of apple trees and consequently enhance the fruit productivity. [References: 19]