Agriculture Reference
In-Depth Information
Lawson
et al
., 2002). In addition, increased CO
2
levels may partially alleviate the detrimental ef-
fects of drought (Fleisher
et al
., 2008a,b). The
rise in atmospheric CO
2
levels associated with
climate change has the potential to increase the
photosynthesis of plants, growth of crops, and
WUE (Polley, 2002).
Stomatal closure is the dominant factor af-
fecting photosynthesis during moderate drought.
Severe drought can inhibit critical metabolic pro-
cesses (Flexas and Medrano, 2002). With com-
plete stomatal closure, gas exchange shifts from
stomatal to cuticular control (Boyer
et al
., 1997).
Cuticular wax may be an important factor in de-
termining drought tolerance (Coleman, 1986;
Kosma
et al
., 2009) and is amenable to genetic
analysis (e.g. Lu
et al
., 2012).
hydration, avoiding cellular desiccation damage
and promoting drought resistance in crop plants
(Jones, 1998; Chaves and Oliveira, 2004; Blum,
2011). In wheat, potassium accumulation under
drought stress (controlled by a recessive osmo-
regulation gene,
or
) has been linked to greater
yield (Richards, 2006). Many plant species nat-
urally accumulate glycine, betaine, and proline
when subjected to different abiotic stresses. These
compounds are thought to be involved in medi-
ating OA and in protecting subcellular structures
in stressed plants (Ashraf and Foolad, 2007).
Factors other than OA may play important
roles in potato production. In conjunction with
water status analysis, the protective roles of small
proteins such as dehydrins need to be studied in
potato (Cellier
et al
., 1998, 2000; Jones, 2007).
7.6
Irrigation Management
Leaf senescence
Accelerated senescence of leaves is a common
response to abiotic stresses such as drought. Be-
cause of the loss of major photosynthetic organs,
potato plants will often exhibit reduced yields. To
optimize the plant's response to drought, ma-
nipulation of leaf senescence may be an import-
ant goal for crop management (Rivero
et al
.,
2007). However, resistance to drought-induced
leaf senescence did not provide a consistent re-
sponse in soybean and sorghum when their
“stay green” lines were studied. An analysis of the
benefits of increased functional leaf life for
potato production would be a useful goal.
In view of the great susceptibility of potato to
drought, as well as a decrease in water resources,
farmers are challenged to save water without
sacrificing yield or quality. Optimized water use,
avoiding wastage and leakage, and employment
of efficient irrigation protocols have been recom-
mended. For example, the introduction of effi-
cient irrigation technologies such as micro- and
trickle irrigation systems has been suggested
(Lamm
et al
., 2007). The low-pressure (LPS) drip
irrigation system designed to operate at low
pressures (0.14-0.21 kg cm
-2
), and with drip-
pers of low low rates, was shown to conserve
40% of the irrigation water in potatoes grown
in Mexico compared to the common flooding ir-
rigation system (Dowgert
et al
., 2006).
Attempts to save water have prompted the
assessment of deficit irrigation protocols and the
development of precision irrigation for reducing
inputs and increasing resource-use efficiency
to improve sustainability (Fereres and Soriano,
2007; Sepaskhah and Ahmadi, 2010).
7.5
Osmotic Adjustment
Osmotic adjustment (OA) in potato may be im-
portant in dealing with drought stress (Levy,
1983, 1992; Coleman, 1986; Jefferies, 1993;
Heuer and Nadler, 1998). In arid climates, po-
tato crops can be exposed to transient drought
and heat stress resulting from high ambient
temperatures and low air humidity. Leaf wilting
is often observed, and may lead to a loss of tuber
yield and quality. Leaf turgor may be preserved
by OA, and this situation can promote faster recov-
ery on alleviation of drought stress (Levy, 1992).
Solute accumulation during a decline in leaf
water potential is important for maintaining leaf
Deficit irrigation and partial
root zone drying
Potato fields fully covered with green active can-
opy are commonly irrigated with amounts at-
tempting to restore evapotranspiration demand
