Relations between carbohydrate, water status and adventitious root formation in leafy pea cuttings rooted under various levels of atmospheric CO₂ and relative humidity

Abstract

Three levels of atmospheric CO2 and 2 levels of relative humidity (RH) during the rooting period were tested for their effect on several factors presumed to influence adventitious root formation in leafy pea (Pisum sativum L. cv. Alaska) cuttings. Compared to normal CO2 levels (350 μl l−1), neither 1800 nor 675 μl l−1 CO2 affected the rooting percentage or the number of roots per cutting. However, 1800 μl l−1 CO2 increased root and shoot dry weight, root length, carbohydrate levels in the base of the cuttings and water potential (Ψw) of cuttings compared to normal levels of CO2. Compared to 87% RH. 55% RH decreased all of the above parameters, including the number of roots per cutting. A polyvinyl chloride antitranspirant (which partially blocks stomata and slows photosynthesis) applied simultaneously with 87% RH increased Ψw and root length but lowered all of the other above parameters, compared to 87% RH without antitranspirant. Increasing current photosynthate (products of photosynthetic activity after excision), carbohydrate, or Ψw either alone or together was associated with increased root system size but not necessarily with increased rooting percentage or root number. The data are consistent with a hypothesis that the number of roots per cutting increased with increasing current photosynthate and carbohydrate until some other factor became limiting. Also, the effect of Ψw on rooting percentage and root number was mediated through its effect on current photosynthate and carbohydrate.

Rising CO2 levels and their potential significance for carbon flow in photosynthetic cells

“…In other species, including Citrus (Koch etal,, 1986) and tropical trees (Oberbauer, Strain & Fetcher, 1985), tnain shoot growth is increased. In pea cuttings, adventitious roots grew larger and had higher carbohydrate levels in enhanced CO2 (Davis & Potter, 1989). The induction of flowering in Pharbitis in enhanced CO2 might also, speculatively, be related to increased supply of carbohydrate (Hinklenton & Jolliffe, 1980).…”

Effects of Elevated Atmospheric Carbon Dioxide on Insect‐Plant Interactions

“…Despite some acclimatization, augmented photosynthesis and reduced photorespiration under enhanced CO 2 levels generate plants with lower total nitrogen, higher ratios of carbon to nitrogen (C:N; Lawler et al 1997), and increased carbohydrate levels (Osbrink et al 1987;Yelle et al 1989;Ahmed et al 1993;Mitchell et al 1993). This leads to greater root and shoot dry weight and greater root length (Davis & Potter 1989;Johnson & Lincoln 1990) and occasionally to improved yields (Allen et al 1991;Stockle et al 1992 a ; but see Mitchell et al 1993). Because increased photosynthesis rates can result in more biomass accumulation, the sustainability of elevated photosynthetic activity and the potential compensatory response to insect feeding depend strongly on the availability of nutrients for plant growth (Trumble et al 1993).…”

Impact of enriched CO2 fumigation effects on plant-insect interaction: feeding behaviour and growth of early and late instar larvae of the cotton leaf worm Spodoptera littoralis (Lepidoptera: Noctuidae)

“…Growth rates (GR) of 4 th instar larvae were lower when fed foliage from the two CO 2 regimes (Table 2). Reduced larval growth rates, such as those induced by the high CO 2 -grown diets in this study, may prevent larvae from completing development in climatically limited environments with short growing seasons (Watt et al, 1995;Davis & Potter, 1989). Reduced growth rates of the larvae fed enriched CO 2 -grown leaves may also increase their exposure to predators and parasitoids (Ottman et al, 2001;Carlson & Bazzaz, 1980;Davis & Potter, 1989).…”

“…Although late S. littoralis larvae consumed additional high CO 2 -grown leaves, they showed slower growth with longer larval duration (Table 1). Reduced growth of late instar larvae on a high CO 2 -grown diet probably resulted from their inability to fully compensate for the diet's reduced nitrogen; they were forced to metabolize food at higher flow rates, such as when they consumed additional high CO grown foliage, they could not process enough food effectively to compensate for lower nitrogen concentrations (Rogers et al, 1994;Davis & Potter, 1989). * HS -highly significant (P < 0.01); S -significant (P < 0.05); N -insignificant (P ≥ 0.05).…”