A B73 x Palomero Toluqueño mapping population reveals local adaptation in Mexican highland maize

Generations of farmer selection in the central Mexican highlands have produced unique maize varieties adapted to the challenges of the local environment. In addition to possessing great agronomic and cultural value, Mexican highland maize represents a good system for the study of local adaptation and acquisition of adaptive phenotypes under cultivation. In this study we characterize a recombinant inbred line population derived from the B73 reference line and the Mexican highland maize variety Palomero Toluqueño. B73 and Palomero Toluqueño showed classic rank-changing differences in performance between lowland and highland field sites, indicative of local adaptation. Quantitative trait mapping identified genomic regions linked to effects on yield components that were conditionally expressed depending on the environment. For the principal genomic regions associated with ear weight and total kernel number, the Palomero Toluqueño allele conferred an advantage specifically in the highland site, consistent with local adaptation. We identified Palomero Toluqueño alleles associated with expression of characteristic highland traits, including reduced tassel branching, increased sheath pigmentation and the presence of sheath macrohairs. The oligogenic architecture of these three morphological traits supports their role in adaptation, suggesting they have arisen from consistent directional selection acting at distinct points across the genome. We discuss these results in the context of the origin of phenotypic novelty during selection, commenting on the role of de novo mutation and the acquisition of adaptive variation by gene flow from endemic wild relatives.

Hubungan Kepemilikan Aset Produksi terhadap Keputusan Petani untuk Menggunakan Varietas Unggul Baru Pepaya Merah Delima (The Association of Production Assets on Farmer Selection of A New Variety, Merah Delima Papaya)

<p>Keputusan untuk mengadopsi varietas atau teknologi baru, terutama bagi petani skala kecil, sangat dipengaruhi oleh kepemilikan sumber daya. Tujuan penelitian ini adalah mengevaluasi pengaruh kepemilikan aset produksi petani terhadap keputusan petani menggunakan Varietas Unggul Baru (VUB) pepaya Merah Delima. Survei dilaksanakan di beberapa sentra produksi pepaya (Sumatra Barat, Riau, Jawa Timur, Jawa Tengah, dan Jawa Barat) melibatkan 46 responden terpilih yang terdiri atas 17 petani pengguna pepaya Merah Delima dan 29 petani penanam pepaya varietas lainnya. Faktor-faktor determinan penggunaan varietas dianalisis dengan menggunakan model regresi Logit dan Tobit. Ketersediaan sarana dan prasarana produksi berpengaruh signifikan terhadap keputusan petani menggunakan VUB pepaya Merah Delima. Pengaruh sarana dan prasarana produksi terhadap probabilitas peningkatan penggunaan varietas lebih dominan dibanding pengaruh faktor-faktor lainnya. Oleh karena itu, program pengembangan VUB pepaya Merah Delima lebih lanjut disarankan perlu didukung dengan bantuan penyediaan alat semprot (sprayer) bertenaga mesin atau ditargetkan di lokasi-lokasi yang tidak terlalu bermasalah dengan tata kelola air.</p><p><strong>Keywords</strong></p><p>Adopsi; Pepaya Merah Delima; Varietas Unggul Baru</p><p><strong>Abstract</strong></p><p>The decision to adopt a new variety or technology, especially for small-scale farmers, is heavily influenced by resource ownership. The purpose of this study was to evaluate the effect of farmer production asset ownership on farmers’ decisions to use Merah Delima papaya high yielding variety (HYV). The survey was conducted in several papaya production centers (West Sumatra, Riau, East Java, Central Java, and West Java) involving 46 selected respondents consisting of 17 farmers using Merah Delima papaya and 29 farmers growing other papaya cultivars. The determinants of farmer decision were analyzed using the Logit and Tobit regression models. The results show that the availability of production facilities and infrastructure has significant effects on farmers’ decisions to use Merah Delima papaya HYV. The influence of production facilities and infrastructure on the probability of increasing the usage of Merah Delima papaya is more dominant than the influence of other factors. Therefore, it is recommended that further Merah Delima papaya HYV development program needs to be supported by the assistance of providing farmers with machine-powered sprayers or prioritized at locations that have few water/irrigation management problems.</p>

Crop selection in dryland of North Lombok Regency: farmers search for more money and less risk

Dryland areas of North Lombok can be grown with a variety of crops and provide alternatives for farmers. This paper aims to: (1) identify farmer selection of crops in dryland areas of North Lombok Regency, Indonesia; (2) analyze farmer decisions in selecting the crops in the area. Results of this study can become the basis for developing agriculture in the area or other areas of similar conditions. Data were collected through surveys to sampled farmers in the dryland areas of North Lombok, with the focus of questions on farmer reasoning following their crop selection. Such an approach is guided by qualitative research principles, highlighting the importance of understanding and meaning of topics investigated. The surveys revealed that in dryland areas of North Lombok grew corn, rice (of dryland type), peanuts, long beans, chili, tomatoes, and cassava. Corn is a dominant crop among farmer choices. In their farming activities, farmers did not select soybean, one of the targeted crops. Farmer reasons behind crop selection directed to the conclusion that farmers in dryland areas of North Lombok are rational, in which they aim to generate high income from their activities and at the same time attempt to reduce risks associated with the chosen crops. This study results imply the importance of understanding the motivations of growers as the primary stakeholder in implementing farming.

On Farm Varietal Diversity and Prevalence of Aspergillus Contamination of Groundnut (Arachis Hypogaea L.) in Major Production Areas of Oromia Region, Ethiopia

Background: Groundnut is one of the most valuable cash crops and food sources in low lands of Ethiopia. In spite of its food and economic importance, very few studies have been conducted yet on the factors that influence groundnut production including aflatoxigenic fungi in different socio-ecological conditions. Therefore, this study aimed at i) assessing groundnut varietal diversity ii) to determine the existing use values and management practices iii) to isolate and determine the prevalence of Aspergillus species associated with groundnut seed.Methods: Field data were collected using structured and semi-structured interviews from 144 general informants and 24 key-informants. 88 groundnut seed samples were collected from farmers’ fields for Aspergillus species isolation. Diversity of groundnut was analyzed using the Shannon diversity index. Frequency of Aspergillus contamination was determined using plate counting methods.Results: In the study areas, six varieties were grown with varying distribution. Shannon diversity indices ranged from 0.20 to 1.27 in warm sub-humid lowland and warm moist lowland agro-ecological zones, respectively. Of the four varieties observed in East Hararghe, oldhale was the most commonly grown variety (66% of groundnut growers), whereas farmers interviewed in East Wellega zone grow bure variety (87% of growers), due to greater drought tolerance and higher yields relative to other varieties. Results of the fungal species analysis showed infestation of groundnut seeds by A.niger, A. flavus, A. prasaticus and A. ochraceous. Of the four Aspergillus species, A. niger and A. flavus were the most prevalent, with frequency ranging from 17.8 to 37.5% and 14.4 to 32.5%, respectively. However, when we compare infection rates among varieties, we did not find statistically significant differences in the infection rates of different varieties collected from similar agroecology of the study area.Conclusion: Different varieties of groundnut were grown with varying distribution based on the farmers’ preference criteria in different socio-ecological zones of the study areas. Although these varieties vary in terms of morphological features and disease resistance, there is not sufficient evidence to conclude they are differentially resistant to Aspergillus infection. Therefore, further breeding for more varieties using farmer selection criteria in mind and research identify field management measures against Aspergillus will further increase groundnut production and hence income for resource poor farmers

A B73 x Palomero Toluqueo mapping population reveals local adaptation in Mexican highland maize

Generations of farmer selection have produced a unique collection of traditional maize varieties adapted to the environmental challenges of the central Mexican highlands. In addition to agronomic and cultural value, Mexican highland maize represents a good system for the study of local adaptation and acquisition of adaptive phenotypes under cultivation. In this study, we characterized a recombinant inbred line population derived from the cross of the B73 reference line and the Mexican highland maize variety Palomero Toluqueo. Evaluation over multiple years in lowland and highland field sites in Mexico identified genomic regions linked to yield components and putatively adaptive morphological traits. A region on chromosome 7 associated with ear weight showed antagonistic allelic effects in lowland and highland fields, suggesting a trade-off consistent with local adaptation. We identified several alleles of highland origin associated with characteristic highland traits, including reduced tassel branching, increased stem pigmentation and the presence of stem macrohairs. The oligogenic architecture of characteristic morphological traits supports their role in adaptation, suggesting they have arisen from consistent directional selection acting at distinct points across the genome. We discuss these results in the context of the origin of phenotypic novelty during selection, commenting on the role of de novo mutation and the acquisition of adaptive variation by gene flow from endemic wild relatives.

On Farm Varietal Diversity and Prevalence of Aspergillus Contamination of Groundnut (Arachis hypogaea L.) in Major Production Areas of Oromia Region, Ethiopia

Background: Groundnut is one of the most valuable cash crops and food sources in low lands of Ethiopia. In spite of its food and economic importance, very few studies have been conducted yet on the factors that influence groundnut production includingaflatoxigenic fungi in different socio-ecological conditions. Therefore, this study aimed ati) assessing groundnut varietal diversity ii) to determine the existing use values and management practices iii) to isolate and determine the prevalence of Aspergillus species associated with groundnut seed.Methods: Field data were collected using structured and semi-structured interviews from 144 general informants and 24 key-informants. 88 groundnut seed samples were collected from farmers’ fields for Aspergillus species isolation. Diversity of groundnut was analyzed using the Shannon diversity index. Frequency of Aspergillus contamination was determined using plate counting methods.Results: In the study areas,six varieties were grown with varying distribution. Shannon diversity indices ranged from 0.20 to 1.27in warm sub-humid lowland and warm moist lowland agro-ecological zones, respectively. Of the four varieties observed in East Hararghe, oldhale was the most commonly grown variety (66% of groundnut growers), whereas farmers interviewed in East Wellega zone grow bure variety (87% of growers), due to greater drought tolerance and higher yields relative to other varieties. Results of the fungal species analysis showed infestation of groundnut seeds by A.niger, A. flavus, A. prasaticus and A. ochraceous. Of the four Aspergillus species, A. nigerand A. flavus were the most prevalent, with frequency ranging from 17.8 to 37.5% and 14.4 to 32.5%, respectively.However, when we compareinfection rates among varieties, we did not find statistically significant differences in the infection rates of different varieties collected from similar agroecology of the study area.Conclusion: Different varieties of groundnut weregrown with varying distribution based on the farmers’ preference criteria in different socio-ecological zones of the study areas. Although these varieties vary in terms of morphological features and disease resistance, there is not sufficient evidence to conclude they are differentially resistant to Aspergillus infection. Therefore, further breeding for more varieties using farmer selection criteria in mind and research identify field management measures against Aspergillus will further increase groundnut production and hence income for resource poor farmers