Effect of Root Zone Temperature on Oilseed Rape ( Brassica napus ) Response to Boron

Abstract

Oilseed rape (Brassica napus) is sensitive to low boron (B) supply, and its growth response to B may be influenced by soil temperature. To test the relationship between B and temperature, oilseed rape (cv. Hyola 42) seedlings were grown at 108C (low) root zone temperature (RZT) with B supply from deficient to adequate B levels until growth of low B plants just began to slow down. Half of the pots were then transferred to 208C (warm) RZT for 11 days before they were moved back to 108C RZT for the final 4 days. Both plant dry mass and B uptake increased after plants were exposed to warm RZT. However, plant B deficiency was exacerbated by warm RZT in low B plants because of increased relative growth rate and shoot -root ratio without a commensurate increase in B uptake rate. It is concluded that RZT above the critical threshold for chilling injury in oilseed rape can nevertheless affect 2791 the incidence of B deficiency by altering shoot-root ratio and hence the balance between shoot B demand and B uptake.

Ionomic response ofLotus japonicusto different root-zone temperatures

“…1). Similar results were also reported for potato (Baghour et al 2001(Baghour et al , 2002a(Baghour et al , 2002b(Baghour et al , 2002c(Baghour et al , 2003, Brassica napus (Ye et al 2006) and tropical cucurbitaceous plants (Zhang et al 2008): within the RZT range of 20-27 C, the total biomass increased in plants, while outside this range the dry weight fell. Effect of low RZT has been previously emphasized; Engels and Marschner (1990) found that low root temperatures not only delayed root growth but also reduced the shoot growth of corn plants.…”

“…Since shoot growth was enhanced by ambient RZT and the concentrations of most elements were highest at this temperature, it is very likely that phyto-accumulation was highest at ambient RZT. Similarly, reductions in phyto-accumulation of Zn, Cu, Mo, B, Al, Ba and Ni at RZT < 20 C have been reported (Baghour et al 2002c(Baghour et al , 2002dYe et al 2006) …”

“…In Brassica napus at RZT as low as10 C there were decreased shoot/root ratios of B (Ye et al 2006). The low level of mineral uptake and the subsequent partitioning into root and shoot may be associated with reduced root function, which can significantly limit solute uptake (George et al 2002a(George et al , 2002b due to reduced root hydraulic conductivity and/or transpiration rate (Marschner 1995).…”

Temperature responses of roots: impact on growth, root system architecture and implications for phenotyping

“…7). In addition to a potential indirect effect of suboptimal root temperature on reducing water, nutrient or hormone supply (Ali et al 1997(Ali et al , 1998Ye et al 2003), direct inhibition of shoot growth by reduced air temperature around the meristem of oilseed rape plants can significantly affect shoot growth (Ye et al 2006).…”