科研之友
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摘要
Based on the carboxylation kinetics of the C-3 and C-4 photosynthetic pathway, it is anticipated that C-3 crops may be favored over C-4 weeds as atmospheric CO2 increases. In the current study, tomato (Lycopersicon esculentum), a C-3 crop species, was grown at ambient ( 400 mu mol mol(-1)) and enhanced carbon dioxide ( 800 mu mol mol(-1)) with and without two common weeds, lambsquarters (Chenopodium album), a C-3 weed, and redroot pigweed (Amaranthus retroflexus), a C-4 weed, from seedling emergence until mutual shading of crop-weed leaves. Because growth temperature is also likely to change in concert with rising CO2, the experiment was repeated at day/night temperatures of 21/12 and 26/18 degrees C. For both day/night temperatures, elevated CO2 exacerbated weed competition from both the C-3 and C-4 weed species. A model based on relative leaf area following emergence was used to calculate potential crop losses from weeds. This analysis indicated that potential crop losses increased from 33 to 55% and from 32 to 61% at the 21/12 and 26/18 degrees C day/night temperatures, for ambient and elevated CO2, respectively. For the current study, reductions in biomass and projected yield of tomato appeared independent of the photosynthetic pathway of the competing weed species. This may be due to inherent variation and overlap in the growth response of C-3 and C-4 species, whether weeds or crops, to increasing CO2 concentration. Overall, these results suggest that as atmospheric CO2 and/or temperature increases, other biological interactions, in addition to photosynthetic pathway, deserve additional consideration in predicting competitive outcomes between weeds and crops. Published by Elsevier B.V.
- 出版日期2013-10
