Open AccessInteracting Effects of Photoperiod and Photosynthetic Photon Flux on Net Carbon Assimilation and Starch Accumulation in Potato Leaves
Author(s) -
Gary W. Stutte,
N.C. Yorio,
Raymond M. Wheeler
Publication year - 1996
Publication title -
journal of the american society for horticultural science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.408
H-Index - 80
eISSN - 2327-9788
pISSN - 0003-1062
DOI - 10.21273/jashs.121.2.264
Subject(s) - photosynthesis , starch , photoperiodism , chemistry , compensation point , horticulture , botany , photorespiration , carbon fixation , light intensity , biology , food science , transpiration , physics , optics
The effect of photoperiod (PP) on net carbon assimilation rate (A net ) and starch accumulation in newly mature canopy leaves of `Norland' potato ( Solanum tuberosum L.) was determined under high (412 ∝mol·m -2 ·s -1 ) and low (263 ∝mol·m -2 ·s -1 ) photosynthetic photon flux (PPF) conditions. The A net decreased from 13.9 to 11.6 and 9.3 μmol·m -2 ·s -1 , and leaf starch increased from 70 to 129 and 118 mg·g -1 drymass (DM) as photoperiod (PP) was increased from 12/12 to 18/6, and 24/0, respectively. Longer PP had a greater effect with high PPF conditions than with low PPF treatments, with high PPF showing greater decline in A net . Photoperiod did not affect either the CO 2 compensation point (50 μmol·mol -1 ) or CO 2 saturation point (1100-1200 μmol·mol -1 ) for A net . These results show an apparent limit to the amount of starch that can be stored (≈15% DM) in potato leaves. An apparent feedback mechanism exists for regulating A net under high PPF, high CO 2, and long PP, but there was no correlation between A net and starch concentration in individual leaves. This suggests that maximum A net cannot be sustained with elevated CO 2 conditions under long PP (≥12 hours) and high PPF conditions. If a physiological limit exists for the fixation and transport of carbon, then increasing photoperiod and light intensity under high CO 2 conditions is not the most appropriate means to maximize the yield of potatoes.