Portal de Periódicos da CAPES

Influences of soil volume and an elevated CO 2 level on growth and CO 2 exchange for the Crassulacean acid metabolism plant Opuntia ficus‐indica

1994; Wiley; Volume: 90; Issue: 1 Linguagem: Inglês

10.1111/j.1399-3054.1994.tb02208.x

1399-3054

Park S. Nobel, Muyi Cui, P. M. Miller, Yiqi Luo,

Plant responses to elevated CO2

Effects of the current (38 Pa) and an elevated (74 Pa) CO 2 partial pressure on root and shoot areas, biomass accumulation and daily net CO 2 exchange were determined for Opuntia ficus‐indica (L.) Miller, a highly productive Crassulacean acid metabolism species cultivated worldwide. Plants were grown in environmentally controlled rooms for 18 weeks in pots of three soil volumes (2 600, 6 500 and 26 000 cm 3 ), the smallest of which was intended to restrict root growth. For plants in the medium‐sized soil volume, basal cladodes tended to be thicker and areas of main and lateral roots tended to be greater as the CO 2 level was doubled. Daughter cladodes tended to be initiated sooner at the current compared with the elevated CO 2 level but total areas were similar by 10 weeks. At 10 weeks, daily net CO 2 uptake for the three soil volumes averaged 24% higher for plants growing under elevated compared with current CO 2 levels, but at 18 weeks only 3% enhancement in uptake occurred. Dry weight gain was enhanced 24% by elevated CO 2 during the first 10 weeks but only 8% over 18 weeks. Increasing the soil volume 10‐fold led to a greater stimulation of daily net CO 2 uptake and biomass production than did doubling the CO 2 level. At 18 weeks, root biomass doubled and shoot biomass nearly doubled as the soil volume was increased 10‐fold; the effects of soil volume tended to be greater for elevated CO 2 . The amount of cladode nitrogen per unit dry weight decreased as the CO 2 level was raised and increased as soil volume increased, the latter suggesting that the effects of soil volume could be due to nitrogen limitations.