Six Tropical Legumes Benefit From CO2 Enrichment in Low Light Conditions

 Source:

http://www.co2science.org/articles/V24/jun/a5.php

Baligar, V.C., Elson, M.K., He, Z.,
Li, Y., Paiva, A.Q., Almeida, A.-A.F.
and Ahnert, D. 2021.

Impact of ambient and elevated [CO2] in low light levels on growth, physiology and nutrient uptake of tropical perennial legume cover crops.

Plants 10, 193, doi.org/10.3390/plants10020193.

"Baligar et al. (was) an experiment studying the response of six tropical legume cover crops to CO2 enrichment at low light levels.

... it is expected that rising CO2 will enhance the growth and survivability of tropical understory plants, which will yield important environmental dividends, including a reduction in:
(1) soil erosion,
(2) nutrient leaching and
(3) weed infestations

    improvements in:
(4, 5) soil organic matter
and nutrient content.

    It will also help to:
(6) conserve soil moisture
and (7) improve soil fertility.

... Baligar et al. (2021) note that "shading is known to reduce yields of many tropical legumes and heavy shade can affect their survivability in plantation crops."

... Baligar et al. report that with few exceptions elevated CO2 and higher light intensity significantly improved net photosynthesis, root length, specific leaf area, root biomass, total biomass and relative growth rate of each of the legume plants.

Observed percentage increases in net photosynthesis and dry weight due to CO2 for each legume at the three different low light intensity treatments ...

... higher CO2 and light intensity improved water use efficiency -- in a number of instances by more than 100% ...

... the authors found interspecific differences among the species, with various micro and macro nutrient concentrations increasing, decreasing or remaining about the same in response to the CO2 and light treatments

... they report elevated CO2 and higher light levels "increased the uptake of all the macro- and micronutrients [examined]," with one exception ... .

The six plants (were) pinto peanut (Arachis pintoi), desmodium (Desmodium heterocarpon), velvet bean (Mucuna pruriens), pigeon pea (Cajanus cajan), hyacinth bean (Lablab purpureus) and cowpea (Vigna unguiculata).

... CO2 concentrations (were) 400 ppm (ambient) and 700 ppm (elevated)

... light intensities (were) three inadequate levels of photosynthetic photon flux density (PPFD)-- 100, 200 and 400 µmol m-2 s-1, which respectively correspond to around 5.5%, 11% and 22% of incoming PPFD at the top of the canopy in tropical regions."