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CO2 Improvements in Maize Xylem Anatomy and Hydraulic Properties

Paper Reviewed
Liu, J., Kang, S., Davies, W.J. and Ding, R. 2019. Elevated [CO2] alleviates the impacts of water deficit on xylem anatomy and hydraulic properties of maize stems. Plant, Cell & Environment 2019,

Introducing their study, Liu et al. (2019) write "as the long-distance, low-resistance water transport pathway in terrestrial plants, xylem allows rapid and substantial movement of water from roots to leaves and is necessary to sustain gas exchange by leaves in a comparatively dry atmospheric environment." Thus, they add, "xylem hydraulic characteristics have a primary control effect on the survival and productivity of plants." Against this backdrop, the four scientists set out to investigate the impacts of elevated CO2 and water availability on the xylem anatomy and hydraulic properties of a plant stem.

The work was conducted in a controlled environment at Shiyanghe Experimental Station, China Agricultural University, Gansu Province, northwest China, in two different years (2016 and 2017). Maize (Zea mays, cv. Qiangsheng 51) was grown from seeds in 15-L pots under one of two water conditions (with or without water deficit) and one of four CO2 concentrations (400, 700, 900 or 1200 ppm).

In reporting their findings, Liu et al. first note that elevated CO2 had a stimulatory effect on maize photosynthesis, leaf area and growth whereas water deficit had a retarding effect on these parameters. However, they say that "the negative impact of water deficit decreased at elevated CO2."

With respect to xylem anatomy and hydraulic traits, the researchers report that elevated CO2 helped to indirectly counter water deficit-induced reductions in xylem anatomy by helping the plants to improve their internal water status and maintain high water potential and turgor pressure. Further, they add that "elevated [CO2] alleviated the negative impact of water deficit to decrease water transport efficiency, with our maize showing lower resistance to long-distance water transport, which is beneficial to the growth of maize due to the close correspondence between assimilation rate and hydraulic conductance."

The results of Liu et al.'s study represent good news for regions that are prone to water deficit conditions. As the air's CO2 rises in the future, plants growing there will be better equipped to deal with that stress, which will translate into better plant growth and yields.

Posted 24 April 2020