Biomass, reproductive output, and physiological responses of rapid‐cycling Brassica (Brassica rapa) to ozone and modified root temperature

Abstract

Brassica rapa L. (rapid-cycling Brassica), was grown in environmentally controlled chambers to determine the interactive effects of ozone (O $ ) and increased root temperature (RT) on biomass, reproductive output, and photosynthesis. Plants were grown with or without an average treatment of 63 ppb O $ . RT treatments were 13 mC (LRT) and 18 mC (HRT). Air temperatures were 25 mC\15 mC day\night for all RT treatments.Ozone affected plant biomass more than did root temperature. Plants in O $ had significantly smaller total plant d. wt, shoot weight, leaf weight, leaf area and leaf number than plants grown without O $ . LRT plants tended to have slightly smaller total plant d. wt, shoot weight, root weight, leaf weight, leaf area, and leaf number than HRT plants. For all variables, LRT plants grown in O $ had the smallest biomass, and plants grown in HRT without O $ had the largest biomass. Ozone reduced both fruit weight and fruit number ; LRT also reduced fruit weight but had no effect on fruit number. Ozone reduced photosynthesis but RT had no effect. Conductance and internal CO # were unaffected by O $ or RT. These studies indicate that plant growth with LRT might be more reduced in the presence of O $ than growth in plants with HRT, which might be able to compensate for O $ -caused reductions in photosynthesis to avoid decreased biomass and reproductive output.

Limitations to CO2 assimilation in ozone‐exposed leaves of Plantago major

“…Light microscopy revealed that the reduction in g s induced by O 3 in both leaves was due to a decline in stomatal aperture, and not to a reduction in stomatal density (Table 1), so the data for leaf 10 suggest that ‘direct’ effects of O 3 on stomatal aperture may have contributed to the O 3 ‐induced decline in g s observed in the present study. This conclusion is supported by other reports of O 3 ‐induced changes in g s independent of effects on the capacity for CO 2 assimilation (Kleier et al. 1998; Torsethaugen et al 1999).…”

Yield and Chemical Composition of Chinese Cabbage in Relation to Thermal Regime as Influenced by Row Covers

“…well as photoassimilates in the shoot (Fu et al, 1993;Kleier et al, 1998). We found that FW as well as DW increased (P < 0.001, data not presented) with plant age.…”

Elevated root-zone temperature hastens vegetative and reproductive development in Shiraz grapevines

“…Because root-zone warming can hasten root reserve mobilisation, canopy development and carbon assimilation (Field et al 2009, Rogiers et al 2011b, this may alter source-sink relations within the plant later in the season with consequences for berry growth and ripening as well as for final fruit size and composition. For instance, a warm root-zone resulted in heavier fruit in canola (Kleier et al 1998) and increased yield in tomatoes (Gosselin andTrudel 1984, Hurd andGraves 1985) and oranges (Cary and Weerts 1980). There are few reports of the effect of root-zone temperature on grape composition with the exception of a set of controlled environment studies carried out in the mid-to late-1970s (Kliewer 1975, Zelleke andKliewer 1979) on Cabernet Sauvignon highlighting lower acidity in berries grown in a warm root-zone.…”