AGRICULTURAL RESEARCH & TECHNOLOGY: OPEN ACCESS JOURNAL-JUNIPER PUBLISHERS
Abstract
Climate change has a strong impact on agricultural
production, which accentuates in developing countries, due to the lack
of technology. From the perspective of food production, we must answer
how to maintain agriculture in developing countries strongly affected by
climate change, population growth, poverty and lack of technological
capacity. The present mini review aims to explore the options that these
communities have, which are fundamentally based on the development of
technologies accessible to their reality, as the use of tolerant species
such as quinoa and aloe or irrigation systems that improve water use
efficiency. This article analyzes mechanisms and strategies of the
plants to improve the efficiency in the use of water and the necessary
requirements to establish a controlled deficit irrigation system
Keywords: Food; Climate change; Water use efficiency; Deficit drip irrigation; Developing countries
Introduction
Traditional agriculture faces the uncertain
conditions of climate change (CC) such as the increase in temperature by
at least 1.7 °C, the increase of the wind force, rainfall regimes
changes and natural production factors decay as soils, water and
diversity [1-6]. This condition imposes a major challenge on
agriculture: Producing food for more than 9000 million inhabitants by
2050 [7], this greater demand for food must be produced with less water
and deteriorated soils. One scenario is that, the deterioration of
resources leads to the abandonment of certain items and to the urgent
search for alternative crops adapted to the new climatic reality,
otherwise there is a risk of the definitive abandonment of agriculture
in various areas affected by the irreversible damage in edaphoclimatic
conditions [8]. There is uncertainty about the ability of improved
traditional crops to adapt to this climate change especially because of
their high homogeneity and dependence on agronomic factors, for instance
availability and soil fertility. Several models indicate that
developing countries will be the most affected, for example, the
decrease in wheat yields is estimated between 20% and 34% [9].
Therefore, a reasonable doubt is: How can developing countries overcome
this situation? The objective of this article is to explore the
technological alternatives available
to developing countries to maintain their agricultural production and
thus the food security of their population.
Discussion
Numerous strategies are possible to apply in this
scenario, from a biotechnological management, through the selection or
modification of genes to create new varieties tolerant of drought or
temperature increase, by means of Precision Farming. Perez et al. [7]
propose an eco-intensive agriculture based on sustainable management of
high technology (computers, remote sensors, drones and precision
agriculture). However, developing countries do not possess sufficient
resources for science and technology development. Therefore, the
alternatives should focus on tools that they may be able to develop and
apply. For instance, cultivating species tolerant to water deficit, the
use of marginal waters or irrigation management with the implementation
of technologies that allow a greater efficiency or through water
restriction methods, known as deficit drip irrigation.
Use of tolerant species
The greatest tolerance to water deficit is observable
in local species and cultivars, in selections that have been made by
farmers for centuries. Quinoa is one of them, it presents various
strategies to overcome stress conditions caused by a decrease
in soil water potential, which can be morpho-physiological
[10,11] and biochemical [12]. Quinoa possesses mechanisms for
the management of plant transpiration throughout modifying
stomatal density and / or stomatal opening [11,13,14]. A
decrease in stomatal conductance not only reduces water loss
but also affects CO2 assimilation. This situation contributes to
a decrease in the efficiency of water use, since less biomass will
be produced per unit of water. When comparing two contrasting
Chilean varieties for the decrease of water potentials, one tolerant
obtained from the altiplano (Amarilla) and another sensitive from
the southern zone (Hueque) [15]. Both selections presented a
decrease in stomatal conductance. This was significantly greater
in the Hueque selection (sensitive variety), in which the stomatal
conductance (gs) fell from 471 to 201 mmol H2O m-2s-1, that
is, a contraction equivalent to 57.3% of the value. Whereas in
Amarilla (tolerant variety) there was only a decrease of 17.4%.
This phenomenon was proportional to the loss of the assimilation
rate, with 37.7% for Amarilla and 65.1% for Hueque [16]. The
previously mentioned experience demonstrates that there are
varieties which maintain productivity despite the water deficit,
turning them into applicable alternatives for the production
of food or other raw materials under these conditions. In CAM
plants, such as Aloe, it is possible to observe other strategies
for instance succulence and slowdown in the delivery of water
stored in their leaves, which is achieved by the synthesis of sugars,
especially neofructans and insulins, which generate an intricate
network of fibers [17,18]. These morphological modifications in
the plant reduce water loss by improving the water use efficiency
WUE) under conditions of water stress [16,19] and maintain their
photosynthetic rates despite being more than 220 days in water
deficit [20].
Controlled drip irrigation
The deficit drip irrigation (DDI) has been defined as a
strategy of optimization of irrigation during the most sensitive
states of a crop to the requirements of irrigation, mainly the
periods of establishment, flowering and filling of fruits. Outside
these periods, irrigation may be restricted. Doorenbos and
Kassam [21], introduce an empirical performance response
factor (Ky) to integrate the complex relationships between water
production and consumption for crop production, which limits its
applicability to make accurate estimations of the responses of the
crop water performance due to other factors such as nutrients,
different cultivated varieties, stress tolerance, among others, also
impact on the performance response, it means that adjustments
must be made for the specific conditions of each site. There are
several studies that demonstrate the benefits of this method. In
paprika [22], in quinoa [23-26], in aloe [27,17] among other crops.
For the application of this method, models such as: Aqua Pro have
been used to simulate the behavior of crops subjected to various
environmental conditions [28] or the ORDI (Optimized Regulated
Deficit Irrigation) [29] model, based on non-linear optimization,
which aims to determine the mentioned combination of stress
levels for arable crops.
In the case of quinoa, an application scheme for DDI is
proposed, which allows starting from 13 pairs of leaves to subject
the plants to a water deficit for 50 days until the emission of
the flora button [30]. Subsequently, it must be maintained with
supplementary irrigation until milky grain for 65 days. Irrigation
is suspended from pasty grains. This proposed model should be
validated for other varieties of quinoa and regions at the same
time, it should be improved considering post-antecedent drought
[31]. The reported values of seed yield per unit of water consumed
(USA) ranged from 0.3 to 0.6kg/m3, in which the low fertility of
the soil [32] and the stress tolerance of the species can have a
lot of influence. In the case of Aloe, the deficit risks can be more
extreme, due to their great capacity to tolerate the water deficit,
in this regard Delatorre-Castillo [20] determined that aloe plants
subjected to 222 days water deficit lose only 15% of the foliar
volume. On the other hand, Oyarce, [19], finds similar results,
evidencing a decrease in water content in Aloe vera leaves as the
restriction period progresses, but an increase in the US with values
14.7kg of dry matter per m3 of water in plants with 25% irrigation
and 12kg of dry matter per m3 of water in treatments with 100%
irrigation, which allows a 75% saving of irrigation water.
Conclusion
Developing countries can improve existing research on the
efficient use of water through the use of water-tolerant species,
using existing information. The use of local tolerant species or
cultivars represent an important alternative, on which scientists
should work, since the improved varieties have high yields, but
also high-water requirements and agronomic factors such as soil
and fertility. It is relevant to return to the traditional varieties
selected for centuries by farmers adapted to their own local
realities. The greater food security of developed countries is
achieved based on the use of technology that often exceeds CO2
emissions and the water footprint, with developing countries
being the most affected.
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