Tree Domestication in Agroforestry: Progress in the Second Decade (2003–2012)

M. Drummond E, Van Tassel DL, Warschefsky EJ. The next era of crop domestication starts now

Current food systems are challenged by relying on a few input-intensive, staple crops. The prioritization of yield and the loss of diversity during the recent history of domestication has created contemporary crops and cropping systems that are ecologically unsustainable, vulnerable to climate change, nutrient poor, and socially inequitable. For decades, scientists have proposed diversity as a solution to address these challenges to global food security. Here, we outline the possibilities for a new era of crop domestication, focused on broadening the palette of crop diversity, that engages and benefits the three elements of domestication: crops, ecosystems, and humans. We explore how the suite of tools and technologies at hand can be applied to renew diversity in existing crops, improve underutilized crops, and domesticate new crops to bolster genetic, agroecosystem, and food system diversity. Implementing the new era of domestication requires that researchers, funders, and policymakers boldly invest in basic and translational research. Humans need more diverse food systems in the Anthropocene-the process of domestication can help build them.

A 20-Year Journey Through an Orphan African Baobab (Adansonia digitata L.) Towards Improved Food and Nutrition Security in Africa

The African baobab (Adansonia digitata L.) is a multipurpose orphan tree species of the semi-arid and sub-humid Sub-Saharan Africa where it plays an important role in rural livelihoods. Its wide distribution and dense nutrition properties make it an important species for food and nutrition security in Africa. However, despite the increasing interest in the species over the past two decades, the full potential of baobab remains underexploited. This review highlights strides made over the past 20 years (2001–2020) towards harnessing and unlocking the potential values of baobab in Benin, West Africa, to contribute to food and nutrition security. Challenges and threats are identified, and next steps suggested to guide research and development initiatives for orphan tree fruit species like baobab to address hunger and malnutrition in Africa.

Comparative analysis of management practices and end-users' desired breeding traits in the miracle plant [Synsepalum dulcificum (Schumach & Thonn.) Daniell] across ecological zones and sociolinguistic groups in West Africa

BACKGROUND

Understanding end-users' preferred breeding traits and plant management practices is fundamental in defining sound breeding objectives and implementing a successful plant improvement programme. Since such knowledge is lacking for Synsepalum dulcificum, a worldwide promising orphan fruit tree species, we assessed the interrelationships among socio-demography, ecology, management practices, diversity and ranking of desired breeding traits by end-users of the species (farmers, final consumers and processing companies) in West Africa.

METHODS

Semi-structured interviews, field-visits and focus groups were combined to interview a total of 300 farmers and final consumers belonging to six sociolinguistic groups sampled from three ecological zones of Benin and Ghana. One processing company in Ghana was also involved. Data collected included socio-demographic characteristics; crop management systems and practices; and preferences of farmers, final consumers and processing companies and ranking of breeding traits. Data were analysed using descriptive statistics, independence, and non-parametric tests, generalized linear models, multi-group similarity index and Kendall's concordance coefficient.

RESULTS

Men (86.33% of respondents) were the main holders of S. dulcificum in the study area. The three most frequent management practices observed in the species included weeding, fertilization and pruning, which were applied by 75.66%, 27.33% and 16.66% of respondents, respectively. The management intensity index varied significantly across ecological zones, sociolinguistic groups, and instruction level (p < 0.001) but was not affected by gender (p > 0.05). General multigroup similarity indices ([Formula: see text]) for farmer-desired traits, on one hand, and final consumer-desired traits, on the other hand, were high across ecological zones ([Formula: see text] ≥ 0.84) and sociolinguistic groups ([Formula: see text] > 0.83). Nevertheless, respondents from the Guineo-Congolian (Benin) and the Deciduous forest (Ghana) zones expressed higher agreement in the ranking of desired breeding traits. Preference for breeding traits was 60% similar among farmers, final consumers, and processors. The key breeding traits desired by these end-users included in descending order of importance big fruit size, early fruiting, high fruit yielding (for farmers); big fruit size, high fruit miraculin content, fruit freshness (for final consumers); and high fruit miraculin content, big fruit size, high fruit edible ratio (for processing companies).

CONCLUSION

This study revealed stronger variations in current management practices across ecological zones than across sociolinguistic groups. A high similarity was shown in end-users' preferences for breeding traits across the study area. Top key traits to consider in breeding varieties of S. dulcificum to meet various end-users' expectations in West Africa include fruit size and fruit miraculin content. These results constitute a strong signal for a region-wide promotion of the resource.

Agro-Fruit-Forest Systems Based on Argan Tree in Morocco: A Review of Recent Results

The argan tree, Argania spinosa (L.) Skeels, is a horticultural forestry species characterized by its endemicity and adaptation to arid and semi-arid zones in the southwest of Morocco. Despite its limited geographical distribution, argan tree presents large genetic diversity, suggesting that improvement of argan is possible. This species plays important ecological, and socioeconomic roles in the sustainable development of the country. The integration of arganiculture into Moroccan agricultural policy has been implemented through a sector strategy, which is fully aligned with the conservation and regeneration of argan forest. A. spinosa is suitable for incorporation into different agroforestry productive systems under agro-fruit-forest model and its domestication will provide a powerful means of socio-economic and environmental management. Here, we provide an overview of the argan tree literature and highlight the specific aspects of argan stands, as agro-forest systems, with the aim of developing an adequate strategy of conservation and domestication of this species. We introduce promising programs and projects for argan plantations and arganiculture, which have been adopted to relieve anthropogenic pressure on the natural argan forest.

From ethnobotany to mainstream agriculture: socially modified Cinderella species capturing 'trade-ons' for 'land maxing'

Over the last 25 years, the process of domesticating culturally-important, highly-nutritious, indigenous food-tree species. Integrating these over-looked 'Cinderella' species into conventional farming systems as new crops is playing a critical role in raising the productivity of staple food crops and improving the livelihoods of poor smallholder farmers. This experience has important policy implications for the sustainability of tropical/sub-tropical agriculture, the rural economy and the global environment. A participatory domestication process has been implemented in local communities using appropriate horticultural technologies to characterize genetic variation in non-timber forest products and produce putative cultivars by the vegetative propagation of elite trees in rural resource centers. When integrated into mainstream agriculture, these new crops diversify farmers' fields and generate income. Together, these outcomes address land degradation and social deprivation-two of the main constraints to staple food production-through beneficial effects on soil fertility, agroecosystem functions, community livelihoods, local trade and employment. Thus, the cultivation of these 'socially modified crops' offers a new strategy for the sustainable intensification of tropical agriculture based on the maximization of total factor productivity with minimal environmental and social trade-offs.

Food applications of Irvingia gabonensis (Aubry-Lecomte ex. O'Rorke) Baill., the 'bush mango': A review

Irvingia gabonensis, also known as 'bush mango', is a multipurpose fruit tree, native to tropical Africa. It is a priority indigenous fruit tree in western and central Africa since its wood is used for making utensils and fruits are mostly used as food and medicine. The objective of this work is to provide an updated review of the available knowledge about physicochemical characteristics of I. gabonensis fruit in order to evaluate its potential use in the food industry. The fruit mesocarp contains various phytochemicals and ascorbic acid concentration higher than some vitamin C rich fruits, then it is consumed fresh or dried, used to produce juice and wine, or as a flavourant. I. gabonensis fruit kernel is rich in oil (63%-69% crude fat), mainly composed of myristic and lauric acids. Its triacylglycerol composition and, resultantly, melting curve and polymorphism indicate an aptitude for diverse applications, as it is solid at room temperature. Forty-one phenolic compounds were identified in the seeds and derived extracts and supplements, being ellagic acid and its derivates the most present. This review enhances our knowledge about nutritional content and health benefits of I. gabonensis whole fruit, especially its pulp and seed, evidencing the need for safer and more efficient production of value-added products.

Nutritional quality of almond, canarium, cashew and pistachio and their oil photooxidative stability

Daily consumption of nuts is recommended as a part of a healthy diet as they contain protein and are rich in beneficial fatty acids and essential nutrients. The nutritional qualities of nuts are affected by their fatty acid composition and other factors such as maturity. Oil oxidative stability is important to determine nut nutritional quality in terms of fatty acid composition over storage. Therefore, this study aimed to (a) assess the nutritional quality (photooxidative stability and nutrient composition) of almond, cashew, pistachio and canarium (a newly commercialised indigenous nut); and (b) explore differences in nutrient concentrations between immature and mature canarium nuts. A decrease in polyunsaturated fats after photooxidation in almond and pistachio was observed. Canarium oil did not change following photooxidation suggesting canarium may display a long shelf life when stored appropriately. Our study indicated that almond provided over 50% of the recommended daily intake for manganese whereas canarium intake provided 50% of the recommended daily intake for iron (for males). Pistachio was richer in potassium compared with other nuts and canarium was richer in boron, iron and zinc than other nut species. Mature canarium kernels were richer in boron, iron and zinc but contained less potassium than immature canarium. Therefore, the current study recommended to store kernels in dark to decrease oil photooxidation, and maturity of canarium kernels at the harvest time was important affecting nutrient concentrations of kernels.

Facilitating smallholder tree farming in fragmented tropical landscapes: Challenges and potentials for sustainable land management

Under changing land use in tropical Asia, there is evidence of forest product diversification through implementation of tree-based farming by smallholders. This paper assesses in two locations, West Java, Indonesia and eastern Bangladesh, current land use conditions from the perspective of smallholder farmers, the factors that facilitate their adoption of tree farming, and the potential of landscape-scale approaches to foster sustainable land management. Data were collected through rapid rural appraisals, focus group discussions, field observations, semi-structured interviews of farm households and key informant interviews of state agricultural officers. Land at both study sites is typically fragmented due to conversion of forest to agriculture and community settlement. Local land use challenges are associated with pressures of population increase, poverty, deforestation, shortage of forest products, lack of community-scale management, weak tenure, underdeveloped markets, government decision-making with insufficient involvement of local people, and poor extension services. Despite these challenges, smallholder tree farming is found to be successful from farmers' perspectives. However, constraints of local food crop cultivation traditions, insecure land tenure, lack of capital, lack of knowledge, lack of technical assistance, and perceived risk of investing in land due to local conflict (in Bangladesh) limit farmers' willingness to adopt this land use alternative. Overcoming these barriers to adoption will require management at a landscape scale, including elements of both segregation and integration of land uses, supported by competent government policies and local communities having sufficiently high social capital.

The role of trees in agroecology and sustainable agriculture in the tropics

Shifting agriculture in the tropics has been replaced by sedentary smallholder farming on a few hectares of degraded land. To address low yields and low income both, the soil fertility, the agroecosystem functions, and the source of income can be restored by diversification with nitrogen-fixing trees and the cultivation of indigenous tree species that produce nutritious and marketable products. Biodiversity conservation studies indicate that mature cash crop systems, such as cacao and coffee with shade trees, provide wildlife habitat that supports natural predators, which, in turn, reduce the numbers of herbivores and pathogens. This review offers suggestions on how to examine these agroecological processes in more detail for the most effective rehabilitation of degraded land. Evidence from agroforestry indicates that in this way, productive and environmentally friendly farming systems that provide food and nutritional security, as well as poverty alleviation, can be achieved in harmony with wildlife.