TITLE:
Elevated Carbon Dioxide and Soil Moisture on Early Growth Response of Soybean
AUTHORS:
M. Madhu, Jerry L. Hatfield
KEYWORDS:
Elevated Carbon Dioxide, Dry Matter, Interaction Effect, Growth Response, Phenology, Root Nodules, Soil Moisture
JOURNAL NAME:
Agricultural Sciences,
Vol.6 No.2,
February
27,
2015
ABSTRACT: Interactions between
elevated [CO2] and soil water availability have the potential impact
on crops and future food security of the world. The study was conducted to investigate
vegetative growth response of soybeans under two [CO2] (380 and 800 μmol
mol-1) with three soil moisture levels in controlled environment. Slow
growth rate and altered crop phenology of soybeans were observed under elevated
[CO2] at early stage (V-3/V-4), but showed positive physiologically response
at later stage (R3) indicating adoptive mechanism
of plants to high [CO2]. Elevated [CO2] decreases the number
of leaves by 23% and 14% and reduces in leaf areas by 11.7% and 9.7% compared with
ambient [CO2] at 29 and 44 days after planting (DAP), respectively. Adaptive
mechanism of plants to high [CO2] produced 39% and 83.7% greater leaf
number and leaf areas, respectively at later stage (R3) of the crop growth (59 DAP).
There was a reduction in a specific leaf area (SLA) at 29 DAP (22.2%) but an increase
at 44 DAP (1.4%) and 58 DAP (8.5%) under elevated [CO2]. Dry matter production
of plants was increased significantly for elevated [CO2]. Increase in
leaf C (12.98%) under
elevated [CO2]. Elevated [CO2] with normal soil moisture condition
produced a maximum number of pods (54.8%
- 122.4%) and an increase in dry weight of pods (29.8% - 56.6%). Plants under
elevated [CO2] produced significantly greater numbers of root nodules
per plant by 114% compared with plants under ambient [CO2] at 44 DAP.
These results show a direct and interactive effect of elevated [CO2]
and soil moisture on plant growth that will affect not only the global food security
but also nutritional security.