Submitted to: American Society of Horticulture Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2003
Publication Date: October 30, 2003
Citation: Baligar, V.C., Bunce, J.A. 2003. Co2 and light intensity effects on growth and nutrition of cacao [abstract]. American Society Of Horticulture Science Meeting.38(5)811. Technical Abstract: In South America, Theobroma cacao (cacao) is grown under various levels of shade. In recent years, concentration of atmospheric levels of CO2 has risen to 370 micromole/mole, with levels expected to double by the end of 21st century. A temperature-controlled greenhouse experiment was undertaken to assess the influence of CO2 and photosynthetic photon flux density (PPFD) on the shoot and root growth and nutrient concentrations of cacao in its early growth stages. Two greenhouses were used to maintain two levels of CO2 (380 and 700 micromole/mole). In each greenhouse, three levels of PPFD, (65, 190, 1050 micromole/squaremeter/second of average light intensity) were achieved by constructing mini shade frames covered with various layers of plastic shade cloth. Plants were grown for 57 days. Increasing CO2 increased shoot parameters (dry wt. of stem and leaves, height, leaf area) and root weight. At both CO2 levels, increasing PPFD from 65 to 190 micromole/squaremeter/second increased growth parameters. PPFD of 1050 micromole/squaremeter/second was detrimental to growth at both levels of CO2, however, its effects were more severe at 380 micromole/mole of CO2. At 380 micromole/mole of CO2, increasing PPFD increased concentrations of Al, K, Mg, Fe and Mn, decreased concentrations of N, Ca, Na, and S, and had no effect on concentrations of P, B, and Cu. At 700 micromole/mole of CO2, increasing PPFD increased concentrations of Al, N, K, Ca, Mg, B, Cu, and Mn, decreased concentrations of Na and S, and had no effect on P concentration. Data from this experiment indicates that light intensity of 190 micromole/squaremeter/second is desirable and increasing levels of CO2 are beneficial to improve cacao growth.