Monday, November 5, 2007
36-4
Effects of Water Deficit and CO2 Enrichment on Potato Development.
Canopy growth and development over the growing season plays a significant role in potato productivity. Potato is drought sensitive and reductions in leaf expansion and canopy growth are observed at mild levels of water stress. Potato productivity is enhanced by elevated atmospheric carbon dioxide concentration ([CO2]), but the interaction of [CO2] and water stress on the dynamics of canopy formation and carbohydrate partitioning have not been documented. Two soil-plant-atmosphere research (SPAR) chamber experiments were conducted at 370 or 740 µmol mol-1 [CO2] and six different levels of irrigation ranging from 10 to 100% of the daily water uptake of the control chamber. Increases in plant length from 23 to 111 cm at 60 days after emergence (DAE), leaf appearance duration from 38 to 71 days, leaf appearance rates from 0.5 to 0.93 leaves d-1, individual leaf area from 50 to 175 cm2, and lateral branch elongation and development were observed as seasonal irrigation increased. These values were generally smaller for elevated [CO2] plants. Total biomass was linearly correlated with seasonal irrigation and increased from 877 to 4151 g m-2. The percentage of biomass allocated to the canopy increased from 50% to 80% with irrigation in ambient [CO2] and 30 to 80% in elevated [CO2]. Despite decreased canopy growth and development, elevated [CO2] plants produced more biomass and yield at most irrigation levels. Reduced canopy mass in elevated [CO2] plants was attributed to suppressed lateral branch development apparently due to an interactive effect of [CO2] enrichment and water stress on tuber sink strength. Data can improve studies evaluating change in management and production strategies for potato production in response to global warming.
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