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Dynamics of Plant Root Growth under Increased Atmospheric Carbon Dioxide

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Title Dynamics of Plant Root Growth under Increased Atmospheric Carbon Dioxide
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Creator M. Madhu
J. L. Hatfield
 
Subject carbon-di-oxide, biological systems.
 
Description Not Available
Plant growth is influenced by above- and belowground environmental conditions and increasing atmospheric carbon dioxide
(CO2) concentrations enhances growth and yield of most agricultural crops. This review covers current knowledge on the impact
of increasing CO2 concentration on root dynamics of plants in terms of growth, root/shoot (R/S) ratio, root biomass, root
length, root longevity, root mortality, root distribution, root branching, root quality, and the response of these root parameters
to management practices including soil water and nutrients. The effects of CO2 concentration on R/S ratio are contradictory due
to complexity in accurate underground biomass estimation under diverse crops and conditions. Roots become more numerous,
longer, thicker, and faster growing in crops exposed to high CO2 with increased root length in many plant species. Branching and
extension of roots under elevated CO2 may lead to altered root architecture and ability of roots to acquire water and nutrients
from the soil profile with exploration of the soil volume. Root turnover is important to the global C budget as well as to nutrient
cycling in ecosystems and individual plants. Agricultural management practices have a greater impact on root growth than rising
atmospheric CO2 since management practices influence soil physical, chemical, and biological properties of soil, consequently
affects root growth dynamics in the belowground. Less understood are the interactive effects of elevated CO2 and management
practices including drought on root dynamics, fine-root production, and water-nutrient use efficiency, and the contribution of
these processes to plant growth in water and nutrients limited environments.

Global climate change has emerged as an important
environmental challenge due to its potential impact
on biological systems on Earth. Atmospheric concentrations
of CO2 have steadily increased from approximately
315 μmol mol–1 in 1959 to a current atmospheric concentration
of approximately 385 μmol mol–1 which converts to an
average annual increase rate of nearly 2 μmol mol–1 (Keeling
and Whorf, 2005). At this rate of increase, concentrations are
projected to reach levels between 500 and 1000 μmol mol–1 by
2100 (IPCC, 2007). Carbon dioxide is not only a major greenhouse
gas, but essential to plant growth (Kramer, 1981; Dahlman
et al., 1985; Warrick, 1988; Kimball, 2011). The flow of C
from photosynthesizing tissues of higher plants, through the
roots and into the soil is one of the key processes in terrestrial
ecosystems. Increases in atmospheric CO2 concentration will
have direct and indirect effects on crop plants and increases in
CO2 will generally increase plant productivity and water-use
efficiency (Drake and Gonzalez-Meier, 1997; IPCC, 2007).
The long-term response to CO2 remains uncertain and will
depend on environmental constraints. Yields of most agricultural
crops will increase under elevated CO2 with productivity
increases in the range 15 to 41% for C3 crops and 5 to 10% for
C4 crops (Cure, 1985; Kimball, 1983; IPCC, 2007; Lotze-
Campen and Schellnhuber, 2009).
Analyses of plant responses to elevated atmospheric CO2
have focused largely on aboveground processes; however, understanding
the effects on photosynthesis are insufficient to answer
questions about overall plant response to a changing atmosphere.
A whole-plant perspective is required to understand the critical
feedbacks and adjustments occurring within a plant and
between plants and soil. An overlooked and under studied aspect
of plant response to rising CO2 is on belowground processes.
The vital role of roots as an interface between the lithosphere and
biosphere is necessary to understand plant response to elevated
CO2. Despite the important role roots play, they have been an
understudied component of agricultural research since they exist
underground. Root health in crop plants will play a major role in
providing sustainable highly productive crops with the ability to
cope with climate changes; however, the effect of increasing CO2
on root growth and development is poorly understood. Climate
change is expected to increase the incidence of extreme weather
events, such as drought, heat waves, and heavy precipitation and
floods, causing crop production to become more variable (IPCC,
2001, 2007; Hatfield et al., 2011). Under these conditions, many
of the environmental factors, for example, water, temperature,
light, nutrition, salinity, air pollutants, and competition have significant
interactions with CO2 concentration on root responses
for numerous species as summarized by Rogers et al. (1994).
Understanding of dynamics of crop roots is important from the
point of view of management of available resources to increase
the productivity of crops and resilience of crops to climate stres
Not Available
 
Date 2020-03-05T08:43:48Z
2020-03-05T08:43:48Z
2013-01-01
 
Type Research Paper
 
Identifier Not Available
Not Available
http://krishi.icar.gov.in/jspui/handle/123456789/33601
 
Language English
 
Relation Not Available;
 
Publisher Not Available