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April 2017
Wheat is an important food and cash crop globally. The crop is sensitive to drought and heat stresses, particularly during flowering and grain filling stages. Over the past decade wheat production and productivity in South Africa and most sub-Saharan African countries declined due to several production constraints, notably by increased recurrent droughts associated with global climate change (Botai et al., 2016; Edossa et al., 2014).
South Africa is the leading wheat producer in sub-Saharan Africa. In the country, a significant area devoted to wheat production is lost to other alternative crops due to drought stress. The country is increasingly reliant on wheat imports to sustain local demands for wheat, which is negatively affecting the wheat industry (DAFF, 2013).
The use of irrigation water for wheat production is expensive, unsustainable and unaffordable. Also, the availability of clean water for irrigation is critical. Other cultural practices such as mulching, fallowing and use of ground cover can be applied to preserve soil moisture. However, breeding for drought and heat tolerant cultivars remains the most complementary, sustainable, feasible and economic approach to drought management.
This enables development and deployment of new varieties with high water use efficiency that produce optimum yield under marginal rainfall conditions to sustainably support wheat growers. Adaptive characteristics selected from drought tolerant lines can be introgressed into popular local varieties which are susceptible to drought stress.
Breeding for drought tolerance requires dedicated research efforts and collaborations among growers: Local, regional and global governmental and NGO scientists. This allows sharing of genetic resources, research facilities and advanced technologies (Mwadzingeni et al., 2016a).
Pre-breeding of wheat for drought tolerance
The research team of ARC-Small Grain in collaboration with the University of KwaZulu-Natal has initiated a drought tolerance pre-breeding programme. The programmes undertake worldwide collection and systematic characterisation of drought-tolerant germplasm that will be made available to breeders and other researchers in South Africa.
Under this initiative, a study was carried out to determine the level of drought tolerance among 88 diverse bread wheat genotypes introduced to South Africa from CIMMYT’s heat and drought nurseries, using eight local checks.
The materials were evaluated under drought stressed and non-stressed conditions in two greenhouses and two field experiments during 2014/2015 and 2015/2016. Water stress was induced from 50% heading to physiological maturity (to mimic terminal drought) by withholding irrigation to 35% field capacity before re-watering.
A custom-made plastic mulch rain-out shelter system was used for field evaluation; eliminating the effects of untimely rainfall (Photo 1 and Photo 2).The initiative is financially supported by the NRF-Research and Technology Fund.
Brief findings of the study
The study selected twelve genotypes (Table 1) with high grain yield and favourable adaptive traits under drought stressed conditions useful for breeding. The yield performance of these genotypes under drought stressed conditions and their stress tolerance indices were above those of local checks evaluated in the study (Mwadzingeni et al., 2016b).
The selected genetic resources were crossed and progeny tests were concluded. The selected parents and families of these crosses will be evaluated and doubled haploid individuals will be extracted to develop pure line cultivars. These materials will be available to breeders. The preliminary outcome of this is made available in the scientific domain (Mwadzingeni et al., 2016b).
For more information contact Mr Learnmore Mwadzingeni at mwadzingenil@ukzn.ac.za.
References
Botai, CM, Botai, JO, Dlamini, LC, Zwane, NS, and Phaduli, E. 2016. Characteristics of droughts in South Africa: A case study of Free State and North West Provinces. Water. 8:439.
Edossa, DC, Woyessa, YE, and Welderufael, WA. 2014. Analysis of droughts in the central region of South Africa and their association with SST anomalies. International Journal of Atmospheric Sciences. 2014: 1 - 8.
Department of Agriculture, Forestry and Fisheries. 2013. Trend in the Agricultural Sector. DAFF, RSA, Pretoria, ISSN 1 025 - 5 028.
Mwadzingeni, L, Shimelis, H, Dube, E, Laing, MD and Tsilo, TJ. 2016a. Breeding wheat for drought tolerance: Progress and technologies. Journal of Integrative Agriculture. 15:935 - 943.
Mwadzingeni, L, Shimelis, H, Tesfay, S, and Tsilo, TJ. 2016b. Screening of bread wheat genotypes for drought tolerance using phenotypic and proline analyses. Front. Plant. Sci. 7:1 - 12.
Publication: April 2017
Section: On farm level
