TY - JOUR
T1 - Exploring the limits of crop productivity
T2 - Beyond the limits of tipburn in lettuce
AU - Frantz, Jonathan M.
AU - Ritchie, Glen
AU - Cometti, Nilton N.
AU - Robinson, Justin
AU - Bugbee, Bruce
PY - 2004/5
Y1 - 2004/5
N2 - The productivity of lettuce in a combination of high light, high temperature, and elevated CO2 has not been commonly studied because rapid growth usually causes a calcium deficiency in meristems called tipburn, which greatly reduces quality and marketability. We eliminated tipburn by blowing air directly onto the meristem, which allowed us to increase the photosynthetic photon flux (PPF) to 1000 μmol·m -2·s-1 (57.6 mol·m -2·d-1); two to three times higher than normally used for lettuce. Eliminating tipburn doubled edible yield at the highest PPF level. In addition to high PPF, CO2 was elevated to 1200 μmol·m-2·mol-1, which increased the temperature optimum from 25 to 30°C. The higher temperature increased leaf expansion rate, which improved radiation capture and more than doubled yield. Photosynthetic efficiency, measured as canopy quantum yield in a whole-plant gas exchange system, steadily increased up to the highest temperature of 32°C in high CO2. The highest productivity was 19 g·d-1 of dry biomass (380 g·d-1 fresh mass) averaged over the 23 days the plants received light. Without the limitation of tipburn, the combination of high PPF, high temperature, and elevated CO2 resulted in a 4-fold increase in growth rate over productivity in conventional environments.
AB - The productivity of lettuce in a combination of high light, high temperature, and elevated CO2 has not been commonly studied because rapid growth usually causes a calcium deficiency in meristems called tipburn, which greatly reduces quality and marketability. We eliminated tipburn by blowing air directly onto the meristem, which allowed us to increase the photosynthetic photon flux (PPF) to 1000 μmol·m -2·s-1 (57.6 mol·m -2·d-1); two to three times higher than normally used for lettuce. Eliminating tipburn doubled edible yield at the highest PPF level. In addition to high PPF, CO2 was elevated to 1200 μmol·m-2·mol-1, which increased the temperature optimum from 25 to 30°C. The higher temperature increased leaf expansion rate, which improved radiation capture and more than doubled yield. Photosynthetic efficiency, measured as canopy quantum yield in a whole-plant gas exchange system, steadily increased up to the highest temperature of 32°C in high CO2. The highest productivity was 19 g·d-1 of dry biomass (380 g·d-1 fresh mass) averaged over the 23 days the plants received light. Without the limitation of tipburn, the combination of high PPF, high temperature, and elevated CO2 resulted in a 4-fold increase in growth rate over productivity in conventional environments.
KW - Ca deficiency
KW - Carbon use efficiency
KW - Crop optimization
KW - Determinants of growth
KW - Quantum yield
KW - Radiation capture
UR - http://www.scopus.com/inward/record.url?scp=1942518792&partnerID=8YFLogxK
U2 - 10.21273/jashs.129.3.0331
DO - 10.21273/jashs.129.3.0331
M3 - Article
C2 - 15776542
AN - SCOPUS:1942518792
VL - 129
SP - 331
EP - 338
JO - Journal of the American Society for Horticultural Science
JF - Journal of the American Society for Horticultural Science
SN - 0003-1062
IS - 3
ER -