SSR genetic diversity assessment of popular pigeonpea varieties in Malawi reveals unique fingerprints

Background: Pigeonpea ( Cajanus cajan L. Millsp.) is a drought tolerant legume of the Fabaceae family and the only cultivated species in the genus Cajanus. It is mainly cultivated in the semi-arid tropics of Asia and Oceania, Africa and America. In Malawi, it is grown as a source of food and income and for soil improvement in intercropping systems. However, varietal contamination due to natural outcrossing causes significant quality reduction and yield losses. In this study, 48 polymorphic SSR markers were used to assess the diversity among all pigeonpea varieties cultivated in Malawi to determine if a genetic fingerprint could be identified to distinguish the popular varieties. Results: A total of 212 alleles were observed with an average of 5.58 alleles per marker and a maximum of 14 alleles produced by CCttc019 (Marker 40). Polymorphic information content (PIC), ranged from 0.03 to 0.89 with an average of 0.30. A neighbor-joining tree produced 4 clusters. The most commonly cultivated varieties, which include released varieties and cultivated land races, were well-spread across all the clusters observed, indicating that they generally represented the genetic diversity available in Malawi, although substantial variation was evident that can still be exploited through further breeding. Conclusion: Screening of the allelic data associated with the five most popular cultivated varieties, revealed 6 markers \u2013 CCB1, CCB7, Ccac035, CCttc003, Ccac026 and CCttc019 \u2013 which displayed unique allelic profiles for each of the five varieties. This genetic fingerprint can potentially be applied for seed certification to confirm the genetic purity of seeds that are delivered to Malawi farmers

Identification of groundnut (Arachis hypogaea) SSR markers suitable for multiple resistance traits QTL mapping in African germplasm

AbstractBackgroundThis study aimed to identify and select informative Simple Sequence Repeat (SSR) markers that may be linked to resistance to important groundnut diseases such as Early Leaf Spot, Groundnut Rosette Disease, rust and aflatoxin contamination. To this end, 799 markers were screened across 16 farmer preferred and other cultivated African groundnut varieties that are routinely used in groundnut improvement, some with known resistance traits.ResultsThe SSR markers amplified 817 loci and were graded on a scale of 1 to 4 according to successful amplification and ease of scoring of amplified alleles. Of these, 376 markers exhibited Polymorphic Information Content (PIC) values ranging from 0.06 to 0.86, with 1476 alleles detected at an average of 3.7 alleles per locus. The remaining 423 markers were either monomorphic or did not work well. The best performing polymorphic markers were subsequently used to construct a dissimilarity matrix that indicated the relatedness of the varieties in order to aid selection of appropriately diverse parents for groundnut improvement. The closest related varieties were MGV5 and ICGV-SM 90704 and most distant were Chalimbana and 47–10. The mean dissimilarity value was 0.51, ranging from 0.34 to 0.66.DiscussionOf the 376 informative markers identified in this study, 139 (37%) have previously been mapped to the Arachis genome and can now be employed in Quantitative Trait Loci (QTL) mapping and the additional 237 markers identified can be used to improve the efficiency of introgression of resistance to multiple important biotic constraints into farmer-preferred varieties of Sub-Saharan Africa

Aflatoxin B1 levels in groundnut products from local markets in Zambia

In Zambia, groundnut products (milled groundnut powder, groundnut kernels) are mostly sold in under-regulated markets. Coupled with the lack of quality enforcement in such markets, consumers may be at risk to aflatoxin exposure. However, the level of aflatoxin contamination in these products is not known. Compared to groundnut kernels, milled groundnut powder obscures visual indicators of aflatoxin contamination in groundnuts such as moldiness, discoloration, insect damage or kernel damage. A survey was therefore conducted from 2012 to 2014, to estimate and compare aflatoxin levels in these products (n = 202), purchased from markets in important groundnut growing districts and in urban areas. Samples of whole groundnut kernels (n = 163) and milled groundnut powder (n = 39) were analysed for aflatoxin B1 (AFB1) by competitive enzyme-linked immunosorbent assay (cELISA). Results showed substantial AFB1 contamination levels in both types of groundnut products with maximum AFB1 levels of 11,100 μg/kg (groundnut kernels) and 3000 μg/kg (milled groundnut powder). However, paired t test analysis showed that AFB1 contamination levels in milled groundnut powder were not always significantly higher (P > 0.05) than those in groundnut kernels. Even for products from the same vendor, AFB1 levels were not consistently higher in milled groundnut powder than in whole groundnut kernels. This suggests that vendors do not systematically sort out whole groundnut kernels of visually poor quality for milling. However, the overall contamination levels of groundnut products with AFB1 were found to be alarmingly high in all years and locations. Therefore, solutions are needed to reduce aflatoxin levels in such under-regulated markets

An assessment of diagnostic tools for improved soil and crop management

Evaluation of soil quality requires the development of a minimum dataset that can be used at different levels and scales. Soil organic matter is a major reservoir of plant nutrients, and hence the dynamics associated with it due to management practices are important. Particulate organic matter (POM) has been suggested as one of the parameters that may be sensitive to management practices and hence can be used to monitor the changes in soil organic matter. The objective of the first study was to investigate the temporal and spatial changes in particulate organic matter when a field that had been under the Conservation Reserve Program (CRP) was plowed. The study was carried out at Taylor County site in southwest Iowa, on a field that had been under pasture for 8 years. Soil samples were collected weekly from mid-June until late October. This study demonstrated that cultivation caused a significant reduction in mineral fraction carbon in just three days. Although the mineral carbon level increased slightly thereafter, it remained below that observed in the uncultivated field. Cultivation increased particulate organic matter at the 15 to 30 cm depth, presumably because of the residue incorporation. A synchronous fluctuation between total organic matter in the whole soil and that found in the mineral fraction showed that the mineral fraction did not control the total amount of carbon in the soil. Particulate organic matter contributed to a higher percentage of the total whole soil organic carbon at the beginning of the season than at the end. It is concluded that particulate organic matter is a sensitive indicator for assessing soil quality effects of post-CRP management practices;Nitrogen fertilizer management has received much attention in the last decade because of its perceived environmental on underground water quality. It has been argued that procedures that would improve its management would lead to improved water quality and be economically feasible because of the savings that farmers would have by applying less fertilizer. Recent studies indicate that the chlorophyll meter can be used as an alternative tool for predicting of nitrogen requirement for corn. A study was initiated at two sites to investigate how various soil management practices affected plant nitrogen concentration, and if the chlorophyll meter could be used to improve nitrogen management. At the Larson farm, five fertilizer treatments were used (0, 67, 134, 201 and 280 kg/N ha) for corn grown using conventional tillage. Chlorophyll meter measurements were made at three growth stages. Similar measurements were made at the Nashua site, but at six growth stages. At the Nashua site, treatments included two tillage and seven management practices. Results from Larson Farm showed a good correlation between fertilizer treatments and chlorophyll meter readings at all growth stages. Grain yield was also highly correlated with chlorophyll meter readings. At the Nashua site, there was good correlation between chlorophyll meter readings at V12 stage and yield. Plant nitrogen content at six growth stages were poorly correlated with yield, probably because of drought stress. There was a good correlation between plant total nitrogen content and chlorophyll meter readings at V6. We conclude that the chlorophyll meter can be used as a tool to improve nitrogen management.</p

Assessing the Competitiveness of Groundnut Production in Malawi: A Policy Analysis Matrix Approach

Groundnut is an important component of the national food supply. It does not only have nutritional and dietary value, groundnut also provides cash to farmers; enrich the soil with nitrogen through biological nitrogen fixation; and its haulms can be used as fodder and fuel. Groundnut production has not kept up with the demands both local and export markets especially in terms of volumes over time. This has been in part due to low average yields resulting from continuous use of unimproved seed. In turn Malawi’s groundnut exports have also generally dwindled over time. The analysis of Malawian groundnut production using the Policy Analysis Matrix methodology shows that both traditional and improved technology groundnut production are both privately and socially profitable. This leads to the conclusion that protectionist policies that would raise domestic groundnut prices above the import parity prices determined in world markets are unnecessary. However, investments in improved technology show profits that are greater than traditional technology. These are likely to be areas in which government investments would yield a significant rate of return and reduce dependence on world markets. In addition to investments in improved seed technology, government should also invest in improved technologies for post harvest handling

IMPROVED LEGUME SEED DEMAND SYSTEMS IN CENTRAL MALAWI: WHAT DO FARMERS’ SEED EXPENDITURES SAY ABOUT THEIR PREFERENCES?

The overall objective of this paper is to assess the demand for improved groundnut, bean, and soybean seed in central Malawi. Specifically, it examines how smallholder farmers respond to changes in market prices of improved legume seed. It also assesses factors that affect the decision to participate in improved seed technology transfer. Considering four commodities namely groundnuts, beans, soybeans and maize, a staple food, the paper estimates a multivariate probit and a linear approximate of the Almost Ideal Demand System (LA/AIDS) using cross section data collected by ICRISAT in 2010. Uncompensated price and expenditure elasticities are reported for the LA/AIDS model. The paper finds high own price elasticities in all four commodities considered. It also indicates that land, household size and education levels affect participation in improved technology. Cross elasticities varied across the commodities considered. As pertain expenditure elasticities, farmers would increase expenditure on improved groundnut and beans if their incomes increased. The results also reveal that if farmers’ incomes increase they would reduce soybean’s expenditure share. The results generally show that farmers are very sensitive to changes in improved legume seed prices and incomes

Improved Legume Seed Demand Systems in Central Malawi: What Do Farmers' Seed Expenditures Say about Their Preferences?

The overall objective of this paper is to assess the demand for improved groundnut, bean, and soybean seed in central Malawi. Specifically, it examines how smallholder farmers respond to changes in market prices of improved legume seed. It also assesses factors that affect the decision to participate in improved seed technology transfer. Considering four commodities namely groundnuts, beans, soybeans and maize, a staple food, the paper estimates a multivariate probit and a linear approximate of the Almost Ideal Demand System (LA/AIDS) using cross section data collected by ICRISAT in 2010. Uncompensated price and expenditure elasticities are reported for the LA/AIDS model. The paper finds high own price elasticities in all four commodities considered. It also indicates that land, household size and education levels affect participation in improved technology. The results further reveal that improved groundnut seed has a substitutive relationship with soybeans. Groundnut and bean cross price elasticity showed an almost unitary relationship with groundnut but groundnut showed complementary relationship with maize seed. Beans showed a less than unitary substitutive relationship with soy and an elastic substitution with maize. Soybean had a substitutive relationship with all seed commodities in question. As pertain expenditure elasticities, farmers would increase expenditure on improved groundnut and beans if their incomes increased. The results also reveal that if farmers’ incomes increase they would reduce soybean’s expenditure share. The results generally show that farmers are very sensitive to changes in improved legume seed prices and incomes

Welfare Effects of Agricultural Technology adoption: the case of improved groundnut varieties in rural Malawi

This paper applies a program evaluation technique to assess the causal effect of the adoption of improved groundnut technologies on consumption expenditure and poverty measured by headcount, poverty gap and poverty severity indices. The paper is based on a cross-sectional farm household level data collected in 2008 from a sample of 594 households in rural Malawi. A sensitivity analysis is conducted to test the robustness of the propensity score based results using the rbounds test and the mean absolute standardized bias (MASB) between adopters and non-adopters. The analysis reveals robust and positive and significant impacts of improved groundnut variety adoption on per capita consumption expenditure and on poverty reduction. The findings generally provide justification for continued public and private investment in groundnut research and outreach in Malawi

SSR genetic diversity assessment of popular pigeonpea varieties in Malawi reveals unique fingerprints

Background: Pigeonpea (Cajanus cajan (L.) Millsp.) is a drought tolerant legume of the Fabaceae family and the only cultivated species in the genus Cajanus. It is mainly cultivated in the semi-arid tropics of Asia and Oceania, Africa and America. In Malawi, it is grown as a source of food and income and for soil improvement in intercropping systems. However, varietal contamination due to natural outcrossing causes significant quality reduction and yield losses. In this study, 48 polymorphic SSR markers were used to assess the diversity among all pigeonpea varieties cultivated in Malawi to determine if a genetic fingerprint could be identified to distinguish the popular varieties. Results: A total of 212 alleles were observed with an average of 5.58 alleles per marker and a maximum of 14 alleles produced by CCttc019 (Marker 40). Polymorphic information content (PIC), ranged from 0.03 to 0.89 with an average of 0.30. A neighbor-joining tree produced 4 clusters. The most commonly cultivated varieties, which include released varieties and cultivated land races, were well-spread across all the clusters observed, indicating that they generally represented the genetic diversity available in Malawi, although substantial variation was evident that can still be exploited through further breeding. Conclusion: Screening of the allelic data associated with the five most popular cultivated varieties, revealed 6 markers – CCB1, CCB7, Ccac035, CCttc003, Ccac026 and CCttc019 – which displayed unique allelic profiles for each of the five varieties. This genetic fingerprint can potentially be applied for seed certification to confirm the genetic purity of seeds that are delivered to Malawi farmers