Stacking tolerance to drought and resistance to a parasitic weed in tropical hybrid maize for enhancing resilience to stress combinations

Open Access JournalMaize is a food security crop cultivated in the African savannas that are vulnerable to the occurrence of drought stress and Striga hermonthica infestation. The co-occurrence of these stresses can severely damage crop growth and productivity of maize. Until recently, maize breeding in International Institute of Tropical Agriculture (IITA) has focused on the development of either drought tolerant or S. hermonthica resistant germplasm using independent screening protocols. The present study was therefore conducted to examine the extent to which maize hybrids simultaneously expressing resistance to S. hermonthica and tolerance to drought (DTSTR) could be developed through sequential selection of parental lines using the two screening protocols. Regional trials involving 77 DTSTR and 22 commercial benchmark hybrids (STR and non-DTSTR) were then conducted under Striga-infested and non-infested conditions, managed drought stress and fully irrigated conditions as well as in multiple rainfed environments for 5 years. The observed yield reductions of 61% under managed drought stress and 23% under Striga-infestation created desirable stress levels leading to the detection of significant differences in grain yield among hybrids at individual stress and non-stress conditions. On average, the DTSTR hybrids out-yielded the STR and non-DTSTR commercial hybrids by 13–19% under managed drought stress and fully irrigated conditions and by −4 to 70% under Striga-infested and non-infested conditions. Among the DTSTR hybrids included in the regional trials, 33 were high yielders with better adaptability across environments under all stressful and non-stressful testing conditions. Twenty-four of the 33 DTSTR hybrids also yielded well across diverse rainfed environments. The genetic correlations of grain yield under managed drought stress with yield under Striga-infestation and multiple rainfed environments were 0.51 and 0.57, respectively. Also, a genetic correlation between yields under Striga-infestation with that recorded in multiple rainfed environments was 0.58. These results suggest that the sequential selection scheme offers an opportunity to accumulate desirable stress-related traits in parents contributing to superior agronomic performance in hybrids across stressful and diverse rainfed field environments that are commonly encountered in the tropical savannas of Africa

Cereal variety and population selection

This research review notes that cereal variety breeding in the last 50 years has been based on pedigree line bred varieties as part of the development of a production system dependent on oil-based inputs. The characteristics desirable for an organic system are frequently at odds with those designed for non-organic systems. Despite this, varietal choice for organic farmers remains largely from the pool of varieties developed for non-organic production. The challenges to address are on what basis can farmers and advisers select varieties, and how to develop varieties suitable for organic production. Plant characteristics are discussed and main desirable features outlined under the headings of: • Nutrient use efficiency • Disease resistance • Weed competitive ability • Quality Breeding selection parameters are then considered. The wide variation that occurs in organic systems and the aim to improve the consistency of performance (yield stability) means that the adaptability of a single variety is not sufficient to buffer these variables. The place for variety mixes is considered, and then the case for composite cross populations. The development of these alternative approaches is hindered by market acceptability and for composite populations by the legislative framework. The conclusions note there are many and different combinations of characteristics that may be of advantage. The suitability of a variety can be affected by the management of the whole organic system, not just one crop in isolation. The situation is complex and selection of genotypes is best undertaken under organic management. Low input line breeding programmes have achieved some success, but the review argues that better environmental adaptation is achieved by genotype diversity, either as variety mixes or as composite populations. For the future there is potential in the (relatively) short term for line breeding under organic conditions. For the longer term there is opportunity in mixtures, and especially of populations. For these to be successfully developed there is a need to address cultural attitudes, inertia in the market and production infrastructure and legislative framework

Yields and qualities of pigeonpea varieties grown under smallholder farmers’ conditions in Eastern and Southern Africa

Pigeonpea is one of the few crops with a high potential for resource-poor farmers due to its complementary resource use when intercropped with maize. A three year comprehensive comparative study on the performance of six pigeonpea (Cajanus cajan) varieties on farmers’ fields in Eastern and Southern Africa where intercropping with maize is normal practice, was undertaken. The varieties were tested for accumulation of dry matter (DM), nitrogen (N) and phosphorus (P) in all above-ground organs for three years under farmers’ conditions. The study revealed that the latest introduced ICEAP 00040 outperformed all the other tested varieties (ICP 9145; ICEAP 00020, ICEAP 00053, ICEAP 00068, and a local variety called “Babati White”) under farmer-managed conditions. The harvest indices (HI), ranging from 0.08-0.15 on dry matter (DM) basis, were relatively low and unaffected (P>0.05) by the environmental variation. The N harvest index (NHI) was 0.28 and P harvest index (PHI) was 0.19. The better responses of ICEAP00040 to favourable conditions could however only be realised in a minority of cases as yields generally were low. These low yields are still a major challenge in African smallholder agriculture as pulses play an important role in soil fertility maintenance as well as in the household diets

MEASURING THE RETURNS TO AGRICULTURAL EXPERIMENT STATION RESEARCH EXPENDITURES FOR CORN, WHEAT AND SOYBEANS

Research and Development/Tech Change/Emerging Technologies,

Worldwide Research Trends on Wheat and Barley: A Bibliometric Comparative Analysis

Grain cereals such as wheat, barley, rice, and maize are the nutritional basis of humans and animals worldwide. Thus, these crop plants are essential in terms of global food security. We conducted a bibliometric assessment of scientific documents and patents related to wheat and barley through the Scopus database. The number of documents published per year, their affiliation and corresponding scientific areas, the publishing journals, document types and languages were metricized. The main keywords included in research publications concerning these crops were also analysed globally and clustered in thematic groups. In the case of keywords related to agronomy or genetics and molecular biology, we considered documents dated up to 1999, and from 2000 to 2018, separately. Comparison of the results obtained for wheat and barley revealed some remarkable different trends, for which the underlying reasons are further discussed

Participatory Plant Breeding Methods for Organic Cereals

Formal breeding methods were not always suitable to address the very large diversity of both environmental conditions and end-user needs. Both were frequently encountered either in marginal areas of developing countries or in organic farms of EEC. Participatory plant breeding (PPB) methods represent alternatives aimed to improve local adaptation breeding, to promote genetic diversity, to empower farmers and rural communities. The term PPB refers to a set of breeding methods usually distinguished by the objectives (functional or process approach), institutional context (farmer-led or formal-led), forms of interaction between farmers and breeders (consultative, collaborative or collegial), location of breeding (centralized or decentralized), stage of farmers participation in the breeding scheme (participatory varietal selection or participatory plant breeding)… Among all these methods, the best strategies for organic breeding and their impacts on breeding techniques are discussed. A PPB program actually conducted at INRA – Montpellier (F), involves the whole organic durum wheat interprofessional organization, from farmers to consumers. It is used to assess the interest of a multidisciplinary approach and to discuss the role of each participant in such program. Must participation be seen as a means towards an end or an end in itself

Agronomy

Climate change is a serious threat to field crop production and food security. It has negative effects on food, water, and energy security due to change in weather patterns and extreme events such as floods, droughts, and heat waves, all of which reduce crop productivity. Over six chapters, this book presents a comprehensive picture of the importance of agronomy as it relates to the United Nations’ Sustainable Development Goals. With an emphasis on the goals of Zero Hunger and Climate Change, this volume examines sustainable agronomic practices to increase crop productivity and improve environmental health

Effect of temperature on the growth and development of quinoa plants (Chenopodium quinoa Willd.): A review on a global scale

The increase in temperature and constant changes in climate negatively affects the development of the plants, which has resulted in an alarming situation for many of the different crops of agricultural and food interest. In the specific case of quinoa, the investigation points to a significant loss in the productivity of the grain crop indicating differences depending on the altitudes of the areas of agriculture production and the availability of water. A current informed description of the responses regarding phonological development under stressful conditions could help us develop appropriate strategies to improve the conditions for the production of quinoa and allow us to propose cultivation of the product under environmental conditions where other products cannot survive. The main discoveries regarding this study were framed within the effect of caloric stress on the germination of quinoa seeds, their phenology, their response to different evaluated cultivars and their effects on their growth as well as their physiological and productive levels. Thus, the analysis is described based on a review of the available scientific documents available in the Scopus database and doctoral work thesis, allowing for the consolidation of the most recent investigations regarding the quinoa and their relationship with temperature

Use of DNA-based genetic markers in plant breeding

Genetic markers have been used since the beginnings of plant breeding, but the concept of linkage and recently the availability of molecular markers have offered new and powerful tools that can help to perform the traditional tasks of selection or that can change the traditional breeding process. Markers can either be used in a descriptive manner to identify varieties, to study the ‘micro-evolution’ of composite crosses or variety mixtures or to analyse the breeding progress retrospectively in order to learn from the past. The operative use of markers in plant breeding is connected to the selection of parental lines and progeny lines. The possible implementation of these processes stretches from the introgression of specific chromosome fragments to ‘marker-based idiotype breeding’

OILSEED ECONOMICS

Crop Production/Industries,