Elias Fereres talks with
ScienceWatch.com and answers a few questions about
this month's Fast Moving Fronts paper in the field of Plant
& Animal Science. The author has also sent along an image
of his work.
Article: Deficit irrigation for reducing agricultural
Authors: Fereres, E;Soriano, MA
Journal: J EXP BOT, 58 (2): 147-159 JAN 2007
Addresses: CSIC, Inst Agr Sostenible, Alameda Obispo S-N,
E-14004 Cordoba, Spain.
CSIC, Inst Agr Sostenible, E-14004 Cordoba, Spain.
Univ Cordoba, Dept Agron, E-14014 Cordoba, Spain.
Why do you think your paper is highly
I believe that there are two primary reasons. First, the paper provides a
background for a variety of research topics aimed at conserving water in
the domain of agricultural water use. The second reason is that it is a
timely work on an issue—deficit irrigation—which recently has
become quite important in the efforts to reduce agricultural water use.
Also, the content of the paper supports renewed research efforts in
advancing scientific knowledge on the crop responses to water deficits, and
on more applied research on irrigation management as well.
Does it describe a new discovery, methodology, or
synthesis of knowledge?
The paper provides a synthesis of knowledge, a comprehensive review of the
subject, and new research findings which prove that deficit irrigation is a
viable option to reduce the consumption of water by crops.
Would you summarize the significance of your paper
in layman's terms?
Elias Fereres (left) and Mario Salinas inspect dataloggers
and associated equipment that were used to record daily
Globally, irrigation uses more than two-thirds of all diverted water. After
decades of improving the efficiency of irrigation systems, the time has
come to reduce the consumption of water by crops. Crops evaporate large
amounts of water; to produce a kg of wheat, more than 500 kg of water are
evaporated. To achieve that goal, deficit irrigation aims at reducing water
application to crops while managing stress levels. The paper provides key
information to advance the design of deficit irrigation strategies, leading
to the reduction of irrigation water requirements.
How did you become involved in this research and
were any particular problems encountered along the way?
Relevant agricultural research under field conditions is usually long-term.
I started conducting irrigation research in 1977 and have included deficit
irrigation experiments in my work since then. There are two major problems
associated with this type of research; one is the inherent variability of
field research that require medium- to long-term efforts (several years at
least) to obtain conclusive results. The other is the usual short-term
funding schemes for research—three years—that prevent the
establishment and successful conclusion of long-term experiments on this
Where do you see your research leading in the
I have been concentrating my efforts recently on the deficit irrigation of
tree crops and vines. This is because they are more amenable to this
approach than many annual crops, and because they are high-value crops with
higher water productivity than annual crops. Also, the information on
deficit irrigation is critical in preventing major losses in perennial
crops in situations of water scarcity.
Do you foresee any social or political
implications for your research?
Yes, deficit irrigation is one approach to reduce agricultural water
consumption, thus releasing water for other uses, including additional
irrigation for increasing future food production, which will be needed to
cope with the anticipated growth in world population. As knowledge
progresses, adoption of these practices will increase the efficiency of
water use in agriculture.
As an example of deficit irrigation, Table 1 of
the paper (shown below) reports the different stress levels experienced by
peach trees under three treatments: full irrigation (FI), and two deficit
irrigation treatments that used 2/3 of the water applied in FI. One was
regulated deficit irrigation (RDI), a treatment that reduces irrigation in
certain developmental stages, and sustained deficit irrigation (SDI), where
the irrigation reduction is constant throughout the season.
The lowest water stress level was experienced by FI, as indicated by the
integrated stem water potential value over the season (-86.7). The SDI
treatment experienced more stress than FI and had lower yields and smaller
fruits (see Table 1). However, the RDI treatment,
despite having experienced more stress than both SDI and FI, had the same
yield and fruit size than FI, and more than the SDI
The explanation is that, in the RDI, water stress was managed in such a
way, by the manipulation of irrigation timing and amounts, as to avoid the
sensitive developmental stages. Thus, fruit growth was not affected, while
vegetative growth was reduced by the water deficits.
The RDI treatment exemplifies how physiological knowledge may be combined
with irrigation management to reduce water use while maintaining yield via
deficit irrigation. This particular experiment was conducted in
Córdoba for six years by Mariá Auxiliadora Soriano,
Carmen Ruz, and Elias Fereres.
Elias Fereres, Ph.D.
Professor of Agronomy
University of Córdoba
Researcher at the Institute of Sustainable Agriculture