Crop Germplasm Research Articles

Development of model web-server for crop variety identification using throughput SNP genotyping data

Crop varieties or genotypes of a given species are pivotal for agricultural production and ownership, management and improvement of their germplasm is a great challenge. Its morphological identification requires time, cost and descriptors are often compromised statistically due to phenotypic plasticity. Development of DNA based signature of varieties can overcome these limitations. There is a global need to implement world trade organization (WTO) and intellectual property rights (IPR) guidelines of Plant Breeders Rights (PBR) where DUS (distinctness, uniformity and stability) testing can be supplemented by DNA profile. Universalization and minimization of SNP number without compromising identification accuracy is the major challenge in development of varietal profile by rapid genotype assay. Besides this, there is no server-based approach reducing computational skill with global accessibility of referral phenotypic and genotypic data. We report world’s first model web server for crop variety identification using >350 Indian wheat varieties and Axiom 35 K SNP chip data. Standard filtering and linkage disequilibrium approach were used to develop varietal signature in Linux using HTML, Java, PHP and MySQL with provision of QR code generator to facilitate bar-coding. Phylogenetic tree constructed by selected SNPs confirms six major trait based clusters of varieties and their pedigree. Our user friendly server based tool, VISTa (Variety Identification System of Triticum aestivum) (http://webtom.cabgrid.res.in/vista) can be used in DUS testing having dispute resolution of sovereignty and access benefit sharing (ABS) issues. This model approach can be used in other crops with pan-global level management of crop germplasm in endeavour of crop productivity.

Screening of maize (Zea mays L.) hybrids based on drought tolerance under hydroponic conditions

Abstract Maize (Zea mays L.) is an important cereal adversely affected by drought stress. Screening the germplasm of maize crop is prerequisite to categorize the genotypes based on drought tolerance and sensitivity. With the objective to sort out the contrasting genotypes, eight maize varieties (V1=FH-988, V2=20R52, V3=FH-1046, V4=Rustam-1, V5=FH-949, V6=Pioneer30Y87, V7=FH-1137, and V8=Rustam-12) were grown under well-watered (WW= 0 MPa) and water stressed (DD = -0.60MPa) conditions. Drought was estimated by applying PEG-8000. Plants were harvested four weeks after transplanting and the evaluation was done on the basis of various morphological (root length, shoot length, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, root shoot ratio, number of leaves) and biochemical parameters (potassium and chlorophyll contents in leaves). Relative leaf water contents and membrane stability index were also measured. The data collected was analyzed statistically at 1% probability level and Least Significant Difference Test (LSD) was applied to separate the significant treatment means. The results showed that the water stress adversely affected on the morphological parameters. The maize hybrid FH-988 had significantly higher (p<0.01) morphological and biochemical parameters and found more drought tolerant. While maize hybrid FH-1137 had lower these parameters as compared to all other maize hybrids and was considered as drought sensitive genotype. Study findings showed that the screening of drought tolerant genotypes could be a better source to mitigate the drought stress impacts on maize in drought prone regions. Keywords: Drought tolerant; Hydroponic; Maize; Water stress http://dx.doi.org/10.19045/bspab.2019.80002

Water use dynamics of dryland canola (Brassica napus L.) grown on contrasting soils under elevated CO2

Increasing atmospheric carbon dioxide concentration ([CO2]) stimulates the leaf-level (intrinsic) water use efficiency (iWUE), which may mitigate the adverse effects of drought by lowering water use in plants. This study investigated the interactive effect of [CO2] and soil type on growth, yield and water use of canola (Brassica napus L.) in a dryland environment. Two canola cultivars (vigorous hybrid cv. ‘Hyola 50’ and non-hybrid cv. ‘Thumper’) were grown in large intact soil cores containing either a sandy Calcarosol or clay Vertosol under current ambient (a[CO2]) and future elevated [CO2] (e[CO2]), ∼550 μmol mol−1). Net assimilation rates (Anet), stomatal conductance (gs) and leaf area were measured throughout the growing season. Seed yield and yield components were recorded at final harvest. Water use was monitored by lysimeter balances. Elevated [CO2]-stimulation of iWUE was greater than the effect on leaf area, therefore, water use was lower under e[CO2] than a[CO2], but this was further modified by soil type and cultivar. The dynamics of water use throughout the growing season were different between the studied cultivars and in line with their leaf development. The effect of e[CO2] on seed yield was dependent on cultivar; the non-hybrid cultivar benefitted more from increased [CO2]. Although textural differences between soil types influenced the water use under e[CO2], this did not affect the ‘CO2 fertilisation effect’ on the studied canola cultivars. Elevated [CO2]-induced water savings observed in the present study is a potential mechanism of ameliorating drought effects in high CO2 environment. Better understanding of genotypic variability in response to water use dynamics with traits affecting assimilate supply and use can help breeders to improve crop germplasm for future climates.

One-step genome editing of elite crop germplasm during haploid induction.

Genome editing using CRISPR-Cas9 works efficiently in plant cells1, but delivery of genome-editing machinery into the vast majority of crop varieties is not possible using established methods2. We co-opted the aberrant reproductive process of haploid induction (HI)3-6 to induce edits in nascent seeds of diverse monocot and dicot species. Our method, named HI-Edit, enables direct genomic modification of commercial crop varieties. HI-Edit was tested in field and sweet corn using a native haploid-inducer line4 and extended to dicots using an engineered CENH3 HI system7. We also recovered edited wheat embryos using Cas9 delivered by maize pollen. Our data indicate that a transient hybrid state precedes uniparental chromosome elimination in maize HI. Edited haploid plants lack both the haploid-inducer parental DNA and the editing machinery. Therefore, edited plants could be used in trait testing and directly integrated into commercial variety development.

Harnessing the potential of germplasm collections.

Contemporary genomics and informatics technologies were used to provide a meaningful and insightful overview of more than 20,000 wild and domesticated barley genotypes from one of the largest crop germplasm collections. The data provide a framework for the rational exploitation of genetic resources in crop improvement, which will be central to addressing global food security.

Development and evaluation of diverse promising rapeseed (Brassica napus L.) mutants using physical and chemical mutagens

Genetic variability is a prerequisite for any plant breeding program, and mutagenesis is a proven way of creating new variation within a crop germplasm. Novel genetic variability in rapeseed was induced by gamma rays, Ethyl Methane Sulphonate (EMS) and combined mutagen treatment, using various doses and concentrations. The objective was to evaluate and compare the obtained M2 mutants for important quantitative traits in two contrasted environments. Data on phenological, morphological and agronomic parameters were recorded. A large variability was observed and mutagenic treatments had a significant effect on all traits studied. Compared to control plants, mutant genotypes derived from seeds treated with low EMS concentrations during moderate time were earlier and characterized by a higher number of pods per plant. For high concentration of EMS during long time and for combinations of physical and chemical mutagens, a significant decrease in plant height and stature was noticed, as compared to control. Besides, plants derived from gamma rays-treated seeds exhibited the highest 1000-seed weight. The novel induced variability may be integrated in rapeseed breeding program as a new germplasm with improved agronomic traits. Particularly, EMS1-7-stable mutant may be exploited to develop efficiently and quickly a new rapeseed cultivar with some desirable traits. The present study highlights once more the possibility to bring novel genetic diversity for rapeseed desirable traits improvement through mutation breeding.

Genetic Diversity and DNA Barcoding of Yam Accessions from Southern Nigeria

Knowledge of genetic diversity and barcoding of yam is lacking in Enugu and Ebonyi States of southern Nigeria. Therefore, DNA barcoding was used to facilitate identification and biodiversity studies of yam species from Southern Nigeria. Seventy five yam accessions were collected from Enugu and Ebonyi States, including International Institute of Tropical Agriculture for DNA extraction and amplification using a chloroplast DNA (cpDNA) ribulose-1,5-bisphosphate carboxylase (rbcL) marker. There was high level of similarity among the accessions and presence of 534 conserved and 7 variable sites. A transversional mutation of G/T at a consensus position of 335 was identified followed by transitions at 362 (A/G), 368 (A/G), 371 (C/T) and 391 (C/T) within the accessions. Phylogeny resolved the yam accessions into ten major groups with their bootstrap values ranging from 0 - 100. Phylogenetic diversity was highest in group X, followed by VII, VI and IX. The inter-group genetic distance based on Kimura 2-parameter model ranged from 0.5000 ± 0.4770 - 5.0560 ± 2.5760, while the intra-group had 0.5250 ± 0.5000 - 2.0103 ± 1.2579. The mean genetic diversity within the entire population was 0.7970 ± 0.06910. BLAST analysis of total bit score, query coverage, and percentage identity were in the ranges of 411 - 1011, 99% - 100% and 97% - 100%, respectively. However, the rbcL could not resolve the yam accessions well following the comparative assessment of some discrepancies in the detected number of species from phylogenetic groupings, genetic diversity indices and NCBI BLAST hits, thereby, exposing the inefficiency of this marker in discriminating the yam accessions. It was demonstrated that rbcL is not an effective marker; therefore, it should not be recommended as a standard-alone marker of choice for DNA barcoding of yam accessions, especially, when accurate identification, discrimination and estimation of genetic diversity of this vital crop are of paramount importance for crop improvement and germplasm conservation.

Comparative proteomic investigation of drought responses in foxtail millet

BackgroundFoxtail millet (Setaria italica L. P. Beauv) has been considered as a tractable model crop in recent years due to its short growing cycle, lower amount of repetitive DNA, inbreeding nature, small diploid genome, and outstanding abiotic stress-tolerance characteristics. With modern agriculture facing various adversities, it’s urgent to dissect the mechanisms of how foxtail millet responds and adapts to drought and stress on the proteomic-level.ResultsIn this research, a total of 2474 differentially expressed proteins were identified by quantitative proteomic analysis after subjecting foxtail millet seedlings to drought conditions. 321 of these 2474 proteins exhibited significant expression changes, including 252 up-regulated proteins and 69 down-regulated proteins. The resulting proteins could then be divided into different categories, such as stress and defense responses, photosynthesis, carbon metabolism, ROS scavenging, protein synthesis, etc., according to Gene Ontology annotation. Proteins implicated in fatty acid and amino acid metabolism, polyamine biosynthesis, hormone metabolism, and cell wall modifications were also identified. These obtained differential proteins and their possible biological functions under drought stress all suggested that various physiological and metabolic processes might function cooperatively to configure a new dynamic homeostasis in organisms. The expression patterns of five drought-responsive proteins were further validated using western blot analysis. The qRT-PCR was also carried out to analyze the transcription levels of 21 differentially expressed proteins. The results showed large inconsistency in the variation between proteins and the corresponding mRNAs, which showed once again that post-transcriptional modification performs crucial roles in regulating gene expression.ConclusionThe results offered a valuable inventory of proteins that may be involved in drought response and adaption, and provided a regulatory network of different metabolic pathways under stress stimulation. This study will illuminate the stress tolerance mechanisms of foxtail millet, and shed some light on crop germplasm breeding and innovation.

Genetic diversity and structure in Amorphophallus spp. Blume ex Decne. using morphological and ISSR markers

ABSTRACTPopulations of many crop wild relatives are at risk and poorly conserved. Characterization of crop germplasm based on assessment of amount, and distribution of genetic diversity, is essential for proper utilization and conservation which could be achieved through morphological and molecular tools. Wild Amorphophallus relatives may be used in breeding to enhance palatability by eliminating tuber acridity, improve yield, and develop collar rot disease resistant varieties. Twenty-five accessions of Amorphophallus, including 7 wild species, 16 morphotypes of A. paeoniifolius var. paeoniifolius (Decne.) Sivad., and “Gajendra” (GJ) and “karunaikizhangu” (T10) – a medicinally important but poorly documented form – cultivars of A. paeoniifolius var. campanulatus (Decne.) Sivad., all collected from biogeographic zones of India, were evaluated using 48 morphological and 17 Inter Simple Sequence repeats (ISSRs) markers. There were differences among accessions for quantitative traits and Shannon-Wiener Diversity Index for qualitative characters. The first 2 principal components, accounting for 56% of variance, were corm and cormel characters. The Unweighted Pair Group with Arithmetic Averages cluster, based on morphological data, indicated two principal clusters with the first principal cluster represented by five wild species, and all A. paeoniifolius accessions in the second principal cluster with GJ and T10 placed far apart. In the ISSRs profile, all accessions of A. paeoniifolius, except T10, clustered together at a bootstrap value of 92.5% despite morphological variability observed in this complex. Within the A. paeoniifolius accessions, moderate diversity (45%) was observed. The accession T10 accounted for 60%–70% dissimilarity with all accessions. Cultivated accessions GJ and T10 evolved separately with anthropogenic intervention to elevate them as cultivated forms. Eight morphotypes of A. paeoniifolius were identified. The non-flowering, special type of the edible accession cv. karunaikizhangu, being placed between the wild species and A. paeonifolius complex provides a mechanism for delineation of taxonomic status of this particular genotype and indicates the need for its conservation.

Climate change: impact, and mitigation strategies for tropical and subtropical fruits

Global warming and climate change is the greatest concern of mankind in the 21st century. Climate change is projected to cause an increase in temperature, variations in rainfall, and an increase in frequency of extreme events such as heat, cold waves, frost days, droughts, floods, etc. Various plant processes like vegetative growth, flowering, fruiting and fruit quality are highly vulnerable to climate changes. Two major parameters of climate changes that have far reaching implications on plants are more erratic rainfall patterns and unpredictable high temperature spells which are consequently expected to reduce crop productivity. Drought reduced fruit set and increased fruit cracking in pomegranate and litchi. An increase in atmospheric temperature and change of rainfall pattern affected the banana cultivation in some countries. In various fruit crops, moisture stress and high temperature during flowering strongly influences the pollen and ovule quality and consequently the fruit set and yield. The promotion of stigma and stamen sterility in papaya is mainly because of the higher temperature, which caused flower drops as well as sex changes in female and hermaphrodite flowers. Flower drop is quite common in mango, guava, litchi and other fruits, if low temperature prevails during flowering. Studies have clearly shown that the population abundance, geographic range and pollination activities of important pollinator species like bees, moths, and butterflies are declining considerably with changing climate. Higher temperature during fruit growth and development increased the incidence of several physiological disorders like spongy tissue and black tip in mango, cracking of fruits, granulation in citrus, etc. Pest ecology of certain crops is changing due to climate change. Fruit fly in guava, carambola, citrus, etc. is becoming alarming due to hot and humid conditions. Warm and humid conditions are also favorable for pests like beetles, bugs and other sucking pests and diseases like mildew, blight, etc. Development of new varieties with higher yield potential and resistance to multiple stresses (drought, flood, salinity) should be the key to maintain yield. Improvement in germplasm of important tropical and subtropical fruit crops for heat stress tolerance should be one of the targets of breeding programs. Location specific soil and water conservation models, protocol for organic farming, conservation horticulture, development of biotic and abiotic stress tolerance rootstocks, etc., are some of the strategies to mitigate the impact of climate change. This paper briefly discussed the impact and mitigation strategies of climate change on tropical and subtropical fruits.

Integrated transcriptomic and metabolomic analyses of a wax deficient citrus mutant exhibiting jasmonic acid-mediated defense against fungal pathogens

Naturally, resistant crop germplasms are important resources for managing the issues of agricultural product safety and environment deterioration. We found a spontaneous mutant of ‘Newhall’ navel orange (Citrus sinensis Osbeck) (MT) with broad-spectrum protections against fungal pathogens in the orchard, postharvest-storage, and artificial inoculation conditions. To understand the defense mechanism of MT fruit, we constructed a genome-scale metabolic network that integrated metabolome and transcriptome datasets. The coordinated transcriptomic and metabolic data were enriched in two sub-networks, showing the decrease in very long chain fatty acid (by 41.53%) and cuticular wax synthesis (by 81.34%), and increase in the synthesis of jasmonic acid (JA) (by 95.23%) and JA-induced metabolites such as 5-dimethylnobietin (by 28.37%) in MT. Furthermore, cytological and biochemical analyses confirmed that the response to fungal infection in MT was independent of wax deficiency and was correlated with the levels of jasmonates, and the expression of plant defensin gene PDF1.2. Results of exogenous application of MeJA and JA inhibitors such as propyl gallate proved that JA-mediated defense contributes to the strong tolerance against pathogens in MT. Our results indicated that jasmonate biosynthesis and signaling are stimulated by the fatty acid redirection of MT, and participate in the tolerance of pathogenic fungi.

Widening the genetic base of cultivated gene pool following introgression from wild Lens taxa

AbstractWild Lens taxa are a reservoir of useful rare genes/alleles for widening the genetic base and synthesis of a new gene pool of lentil. To maximize and sustain lentil production, new gene sources are needed to be identified and incorporated into cultivated background. This needs a comprehensive approach to accumulate favourable alleles from distantly related germplasm for widening of the cultivated gene pool and would be the most appropriate strategy to solve the various problems associated with stressed crop production and plateaued yields. Furthermore, expansion of deeper understanding of lentil genomics along with extensive research undertaken in other crop species can provide suitable guidelines to cover the distribution of Lens genus and component gene pools for further remarkable progress in lentil genetic improvement. This review aims at the genus Lens distribution and gene pools, crop germplasm conserved in ex‐situ and in‐situ collection, wild species characterization and evaluation for useful traits of interest to solve production‐related problems, highlight useful gene sources present in different gene pools and the progress achieved for widening the genetic base of cultivated varieties of lentil through wide hybridization and exploring lentil genomics.

Genetic Loci Governing Androgenic Capacity in Perennial Ryegrass (Lolium perenne L.).

Immature pollen can be induced to switch developmental pathways from gametogenesis to embryogenesis and subsequently regenerate into homozygous, diploid plants. Such androgenic production of doubled haploids is particularly useful for species where inbreeding is hampered by effective self-incompatibility systems. Therefore, increasing the generally low androgenic capacity of perennial ryegrass (Lolium perenne L.) germplasm would enable the efficient production of homozygous plant material, so that a more effective exploitation of heterosis through hybrid breeding schemes can be realized. Here, we present the results of a genome-wide association study in a heterozygous, multiparental population of perennial ryegrass (n = 391) segregating for androgenic capacity. Genotyping-by-sequencing was used to interrogate gene- dense genomic regions and revealed over 1,100 polymorphic sites. Between one and 10 quantitative trait loci (QTL) were identified for anther response, embryo and total plant production, green and albino plant production and regeneration. Most traits were under polygenic control, although a major QTL on linkage group 5 was associated with green plant regeneration. Distinct genetic factors seem to affect green and albino plant recovery. Two intriguing candidate genes, encoding chromatin binding domains of the developmental phase transition regulator, Polycomb Repressive Complex 2, were identified. Our results shed the first light on the molecular mechanisms behind perennial ryegrass microspore embryogenesis and enable marker-assisted introgression of androgenic capacity into recalcitrant germplasm of this forage crop of global significance.

Genetic Diversity, Population Structure, and Genetic Correlation with Climatic Variation in Chickpea (Cicer arietinum) Landraces from Pakistan.

Chickpea ( L.) production in arid regions, such as those predominant in Pakistan, faces immense challenges of drought and heat stress. Addressing these challenges is made more difficult by the lack of genetic and phenotypic characterization of available cultivated varieties and breeding materials. Genotyping-by-sequencing offers a rapid and cost-effective means to identify genome-wide nucleotide variation in crop germplasm. When combined with extended crop phenotypes deduced from climatic variation at sites of collection, the data can predict which portions of genetic variation might have roles in climate resilience. Here we use 8113 single nucleotide polymorphism markers to determine genetic variation and compare population structure within a previously uncharacterized collection of 77 landraces and 5 elite cultivars, currently grown in situ on farms throughout the chickpea growing regions of Pakistan. The compiled landraces span a striking aridity gradient into the Thal Desert of the Punjab. Despite low levels of variation across the collection and limited genetic structure, we found some differentiation between accessions from arid, semiarid, irrigated, and coastal areas. In a subset of 232 markers, we found evidence of differentiation along gradients of elevation and isothermality. Our results highlight the utility of exploring large germplasm collections for nucleotide variation associated with environmental extremes, and the use of such data to nominate germplasm accessions with the potential to improve crop drought tolerance and other environmental traits.

Climate risk management and rural poverty reduction

Climate variability is a major source of risk to smallholder farmers and pastoralists, particularly in dryland regions. A growing body of evidence links climate-related risk to the extent and the persistence of rural poverty in these environments. Stochastic shocks erode smallholder farmers' long-term livelihood potential through loss of productive assets. The resulting uncertainty impedes progress out of poverty by acting as a disincentive to investment in agriculture – by farmers, rural financial services, value chain institutions and governments. We assess evidence published in the last ten years that a set of production technologies and institutional options for managing risk can stabilize production and incomes, protect assets in the face of shocks, enhance uptake of improved technologies and practices, improve farmer welfare, and contribute to poverty reduction in risk-prone smallholder agricultural systems. Production technologies and practices such as stress-adapted crop germplasm, conservation agriculture, and diversified production systems stabilize agricultural production and incomes and, hence, reduce the adverse impacts of climate-related risk under some circumstances. Institutional interventions such as index-based insurance and social protection through adaptive safety nets play a complementary role in enabling farmers to manage risk, overcome risk-related barriers to adoption of improved technologies and practices, and protect their assets against the impacts of extreme climatic events. While some research documents improvements in household welfare indicators, there is limited evidence that the risk-reduction benefits of the interventions reviewed have enabled significant numbers of very poor farmers to escape poverty. We discuss the roles that climate-risk management interventions can play in efforts to reduce rural poverty, and the need for further research on identifying and targeting environments and farming populations where improved climate risk management could accelerate efforts to reduce rural poverty.

Sustainable Agriculture—Enhancing Environmental Benefits, Food Nutritional Quality and Building Crop Resilience to Abiotic and Biotic Stresses

Feeding nutrition-dense food to future world populations presents agriculture with enormous challenges as estimates indicate that crop production must as much as double. Crop production cannot be increased to meet this challenge simply by increasing land acreage or using past agricultural intensification methods. Food production doubled in the past through substantial use of synthetic fertilizer, pesticides, and irrigation, all at significant environmental cost. Future production of nutrition-dense food will require next-generation crop production systems with decreased reliance on synthetic fertilizer and pesticide. Here, we present three case studies detailing the development of cover crops and plant-beneficial microbes for sustainable, next-generation small grain, tomato, and oilseed rape production systems. Cover crops imparted weed and pathogen control and decreased soil erosion and loss of soil nitrogen, phosphorus and carbon, while plant-beneficial microbes provided disease control and phosphorus fertility. However, yield in these next-generation crop production systems at best approximated that associated with current production systems. We argue here that to substantially increase agricultural productivity, new crop germplasm needs to be developed with enhanced nutritional content and enhanced tolerance to abiotic and biotic stress. This will require using all available technologies, including intensified genetic engineering tools, in the next-generation cropping systems.

Simple sequence repeat markers associated/linked with agronomic traits, as core primers, are eminently suitable for DNA fingerprinting in Upland cotton.

Analyzing the genetic differences among crop germplasm resources scientifically and accurately is very important for the selection of core accessions, the identification of new cultivars, and the determination of seed purity. However, phenotypic selection per se is not sufficient to identify genetically distinct accessions. In this study, 26 out of 83 simple sequence repeat markers associated/linked with cotton important agronomic traits derived from our previous and other published research, corresponding to the 26 chromosomes of Upland cotton (Gossypium hirsutum L.), were selected as core primers for DNA fingerprinting construction. The 26 markers showed clear band patterns, good repeatability and high polymorphism. The average alleles, gene diversity index and polymorphism information content were 3.12, 0.4312 and 0.3830, respectively. Using TM-1, a genetic standard line for Upland cotton, as the control, DNA fingerprinting pattern and DNA barcodes were obtained based on the core primers. There was a significant positive correlation between genetic distance matrix determined using 26 core primers and that determined using more primers (335) derived from previous research, further suggesting that the core primers were eminently suitable for DNA fingerprinting in Upland cotton. This study provides a molecular basis for assessing identification, authenticity and seed purity of cotton cultivars.

湖北省钟祥市农作物种质资源系统调查报告

湖北省钟祥市农作物种质资源系统调查报告

Vulnerability of field crops to midcentury temperature changes and yield effects in the Southwestern USA

Increased temperatures in the Southwestern USA will impact future crop production via multiple pathways. We used four methods to provide an illustrative analysis of midcentury temperature impacts to eight field crops. By midcentury, cropland area thermally suitable for maize cultivation is projected to decrease, while area suitable for cotton cultivation expands northward and nearly doubles in extent. The increase in area exposed to daily temperatures > 35 °C was highest for oat and maize. Estimates of yield reduction from heat stress for both maize and cotton indicate that historically, SW heat stress reduced cotton yield by 26% and maize yield by 18% compared to potential yield. By midcentury, we predict yield reduction from heat stress will reduce cotton and maize yields by 37 and 27%, respectively, compared to potential yield. Our results contradict the notion that the warmest counties cultivating field crops will be the most impacted. Rather, future temperature, total crop area and crop sensitivity contribute to more complex county-level impacts. Identification of representative target environments under future temperature regimes can inform development of farm-based networks to evaluate new crop germplasm with increased heat tolerance and viable adaptation and management strategies to respond effectively to future temperatures.

Pathways from research on improved staple crop germplasm to poverty reduction for smallholder farmers

Innovations to improve staple crop germplasm can reduce poverty and otherwise improve farmer livelihoods through complex and multiple pathways. This paper reviews the evidence for one prominent pathway—through increased incomes (in cash and kind) for poor farmers who adopt the technology.An important determinant of poverty reduction is the ability of poor producers to adopt productivity-enhancing varieties, and the paper analyzes recent household-level data from two African countries to examine if poor producers face unique barriers to adoption. A second determinant of poverty reduction is the area available to plant these varieties and whether the intensity of adoption is great enough to significantly reduce poverty. The paper uses a double-hurdle estimation framework to model the adoption/area planted joint decision for maize farmers in Ethiopia and sweet potato farmers in Uganda. The focus of the analysis is the effect of poverty-related variables on adoption/area planted decisions. Farmer wealth, landholding, education, location, and access to support and information services are included to understand how correlates of poverty affect adoption decisions.We find evidence that landholding size is an important barrier to poverty reduction; poor farmers are able to adopt improved varieties, but their intensity is constrained by land availability. In Uganda, farmers at the 95th percentile of adoption area received about $0.13 per person per day from the incremental yield, covering <50% of the mean household poverty gap. This gain only comes under optimistic assumptions and most adopters do not have sufficient area for the direct income effect to be large. The evidence suggests that direct, short-term impacts of increased productivity to increased income may be limited in magnitude. Nonetheless, we recognize that other, less direct pathways may be important, particularly over longer times. Impacts through indirect pathways are, however, more difficult to measure. This has implications for the design of M&E and the crafting of appropriate targets for outcomes of research on staple crops which should focus perhaps on the other pathways where poverty reduction is more probable.