Introduction

Research related to forage genetic resources at the International Center for Tropical Agriculture (CIAT), Cali, Colombia, has been a continuing activity since the inception of the center in 1969. CIAT was the third of the international agricultural research centers established within the Consultative Group on International Agricultural Research (CGIAR), one of its missions being the development of beef cattle production in the lowlands of tropical America (Lynam & Byerlee, 2017). When looking at the development of the CIAT forages collection and its achievements, two phases can be distinguished: the first phase focused on assembling the collection and some initial, however intensive, characterization and utilization of the collected materials (1972‒1993); and the second phase consisted of continuing utilization of germplasm, diversity studies and routine germplasm management and its optimization (1993‒2020).

This paper summarizes the assembling of the collection during the first phase as well as its utilization and germplasm distribution. Furthermore, research on forage diversity and knowledge sharing, including training, are addressed. Data presented were compiled mainly from information accessible via the CIAT website (https://ciat.cgiar.org/), CIAT annual reports (accessible at https://cgspace.cgiar.org/handle/10568/35699), unpublished reports on germplasm collecting missions, research bulletins of CIAT´s national partner institutions and the like.

It should be noted that in the past years there have been changes in plant nomenclature for numerous taxa of particular interest, even at the genus level (Cook & Schultze-Kraft, 2015). In this paper we are still referring to the earlier used names. Supplemental Table 1 lists new names of species mentioned in this report, following the taxonomy of GRIN, the database of the USDA Genetic Resources Information Network (https://npgsweb.ars-grin.gov/gringlobal/taxon/taxonomysearch).

Assembling the forage germplasm collection

At the beginning of research at CIAT in the early 1970s, a focus of the then Beef Production Systems Program was forage-based livestock production on acid, low-fertility soils in humid and sub-humid lowlands of tropical America, particularly savanna areas. The lack of edaphic adaptation of available, mainly Australian commercial pasture grass and legume cultivars, was soon identified as the main constraint to their use in Neotropical savannas. In the case of legumes, diseases, such as anthracnose in the promising genus Stylosanthes, were an additional restriction. It was consequently recognized that available species and genotype pools of grasses and legumes needed to be broadened for screening for adaptation to abiotic (mainly soil) and biotic (pests and diseases) constraints.

Missions were thus initiated in 1972/73 to collect germplasm of wild species with forage potential throughout tropical America. The objective was to create a diverse germplasm pool that can be tapped for cultivar development, either by identifying suitable accessions for direct use or through genetic improvement. These collecting missions ranged from short excursions, particularly within the Center´s host country, Colombia, to field expeditions over several weeks. Another source of germplasm material was through opportunistic collecting undertaken by CIAT scientists during field visits. The missions were largely funded by CIAT, at the beginning of the collecting phase, also with support from the former International Board for Plant Genetic Resources (IBPGR; later International Plant Genetic Resources Institute (IPGRI), now part of the Alliance of Bioversity International and CIAT). There was a focus on acid-soil regions and plant genera of known value. Emphasis was on legumes, in many cases including associated rhizobia, taking into account that the Neotropics are the main center of diversification of the Fabaceae (Leguminosae) family. The particular value of legumes lies in their ability of symbiotic fixation of atmospheric nitrogen and the subsequent provision of protein-rich forage to livestock.

From 1979 onwards, collecting missions within the new Tropical Pastures Program expanded to Southeast Asia, a minor yet important center of legume diversification (e.g. the genera Pueraria and Desmodium), and in 1984/85 and 1989 also to Africa, with focus on grasses (particularly the genus Brachiaria). The latter took into account that Sub-Saharan Africa is the main center of diversification of those genera with forage potential in the Poaceae family.

All missions were organized as joint ventures in association with national research institutions. Table 1 provides an overview of the countries where the collecting efforts were undertaken; the main genera collected are summarized in Table 2. The germplasm collectors who participated in the missions are acknowledged in Supplemental Table 2.

Alongside the collecting activities, the introduction of germplasm in the form of donations from existing collections held by national and international research and development (R&D) institutions around the globe has been an ongoing activity since the inception of the CIAT forages collection. It became the sole source of additions to the collection, when germplasm collecting with the involvement of CIAT scientists came to an end in the 1990s. A total of more than 9,000 accessions were received as donations (Table 3); among them, in 2006, a significant part of the former Australian Tropical Forages Collection of CSIRO (Commonwealth Scientific and Industrial Research Organisation).

Two factors contributed to the cessation of collecting missions: (1) a sustained decline in funding for tropical-forages research and (2) the fact that hardly any tropical-forage species are included in Annex 1 of the International Treaty on Plant Genetic Resources for Food and Agriculture (ITPGRFA; (FAO, 2001), which streamlines germplasm distribution through the use of a Standard Material Transfer Agreement (SMTA). Instead, most tropical forage species are regulated by legal frameworks that require case-by-case negotiations of individual material transfer agreements, which would create unmanageable legal overheads given the frequent germplasm exchange in agricultural research.

Table 4 provides a summary of the current tropical forages collection conserved at the CIAT genebank. Differences of numbers in Table 4 in comparison with Table 3; Table 2 are due to initial misidentifications and losses of accessions due to a range of reasons, including a limited number (or low viability) of collected seeds, lack of seed setting in the environments available for regeneration, and insufficient funds for regenerating large numbers of accessions between the 1990s and the launch of the CGIAR Research Program on Genebanks in the 2010s.

Utilization

Germplasm collecting and introduction activities were the responsibility of the former CIAT Beef Production Systems Program (renamed Tropical Pastures Program (TPP) in 1979) until the late 1980s. Maintenance of the collection passed on to the CIAT Genetic Resources Unit (GRU) after its foundation in 1977 (in 2009 renamed Genetic Resources Program, GRP). Maintenance encompasses activities such as seed testing, seed increase, germplasm preservation at different cold storage levels, safety back-ups of the collection, maintenance of living collections, seed distribution, etc. Standard Operating Procedures (SOP) for each of these areas are available upon request. The collection is conserved in the GRP´s genebank at CIAT Headquarters, Cali, Colombia. At the time of writing (2020), 90% of CIAT’s tropical forages collection is backed-up in the Svalbard seed vault and 77% at CIMMYT (https://ciat.cgiar.org/what-we-do/crop-conservation-and-use/tropical-forage-diversity/).

For effective utilization of the germplasm collection, the close interaction between the genebank and CIAT´s TPP (today: Tropical Forages Program, TFP) played a key role, particularly in the 1980s, in view of the TPP’s germplasm-focused research agenda and its alliances with national R&D institutions. The main research approaches were:

• Multidisciplinary germplasm characterization and evaluation by the TPP with involvement of specialists in the fields of agronomy, plant pathology, entomology, plant and animal nutrition, legume rhizobiology, soils, pasture establishment, pasture utilization, farming systems, economics, plant breeding, and seed production;

• Stepwise categorization of promising accessions as germplasm evaluations proceeded from small-plot observations to ultimately animal production experiments under grazing;

• Multi-site testing of germplasm in different eco-climatic zones at: CIAT-Quilichao (Colombia), Colombia-Llanos (with ICA, at Carimagua), Brazil-Cerrados (with EMBRAPA, at Planaltina), Peru-Humid Tropics (with IVITA, at Pucallpa), and later Central America (with Ministerio de Agricultura y Ganadería, in Costa Rica);

• Networking: multi-location testing of elite germplasm within the networks:

  • RIEPT (Red Internacional de Evaluación de Pastos Tropicales), with national research institution partners in Latin America and the Caribbean);

  • RABAOC/WECAFNET (Reseau de Recherche en Alimentation du Bétail en Afrique Occidentale et Centrale/West and Central African Forage Evaluation Network), with national research institution partners in West and Central Africa and in cooperation with ILCA/ILRI (International Livestock Centre for Africa/International Livestock Research Institute);

  • SEAFRAD (South East Asian Forage and Feed Resources Network), with national research institution partners in Southeast Asia; this network developed in the 1990s into the ACIAR (Australian Centre for International Agricultural Research) funded Forages for Smallholders project;

• Development, publication and use of network-wide common research methodologies (see section Publications below);

• Publication of research results in RIEPT reports (accessible at https://cgspace.cgiar.org/discover?scope=%2F&query=riept) and the TPP’s journal Pasturas Tropicales (accessible at https://tropicalgrasslands.info/index.php/tgft/pages/view/Pasturas).

As a result of the germplasm evaluation and selection research conducted by CIAT and its partners, a number of grass and legume accessions that had been provided by the CIAT forages collection were developed into cultivars by national R&D institutions worldwide, in a few cases after incorporating them in national breeding programs (Table 5). Several issues should be pointed out:

• In relation to cultivars selected from genebank accessions, formal release and/or registration has been and is the exclusive responsibility of national institutions. In the case of bred lines developed at CIAT (not included in Table 5), cultivar release/registration is done by the private sector, with authorization by CIAT.

• Some cases are mentioned where CIAT accessions were adopted by end users without a formal and documented cultivar release; the real number is probably much higher. On the other hand, it is most likely that not all released cultivars were or are actually used by farmers to a major extent. The use of materials from tropical forages genebanks is further discussed byHanson et al. (2020) and Duncan et al. (2020).

• Several important grass varieties, which had been developed by institutions in Brazil [(e.g. Brachiaria brizantha cv. Marandu (CIAT 6294) and Panicum maximum cvv. Tanzânia (CIAT 16031), Mombaça (CIAT 9692) and Tobiatã (CIAT 6299)] and subsequently introduced to CIAT, are not included in Table 5. Nonetheless, CIAT, within its network evaluation activities in Latin America and SE Asia, was instrumental for eventual release and adoption of these cultivars by non-Brazilian end-users.

• Mentioning of cultivar releases of the accessions Brachiaria decumbens CIAT 606 and B. humidicola CIAT 679 is restricted to countries other than Brazil: Both accessions represent early Australian cultivars (‘Basilisk’ and ‘Tully’, respectively) and, unlike the other countries where CIAT-coordinated network evaluations were instrumental for selection and release, adoption in Brazil was an entirely CIAT-independent process.

• Brachiaria spp. accessions that were used by CIAT internally to produce Brachiaria breeding lines and from which hybrid cultivars were developed by globally operating seed companies (Grupo Papalotla, Dow AgroSciences) within public-private-partnership (PPP) agreements, are not included either. Information on those hybrid cultivars (e.g. ‘Mulato’, Mulato II’, ‘Cayman’, ‘Cobra’, ‘Camello’) is available in Cook et al. (2020).

• Table 5 also provides information on the timespan between germplasm acquisition (collection or introduction) and cultivar release.

In the early 1990s, CIAT gradually changed its germplasm utilization research priority from development of grass/legume pastures for acid soils to selection of multipurpose plants for smallholders. This adjustment took into account the need for forage plants to maintain and restore soil fertility, including in mixed (crop-livestock) production systems, and to contribute to increased small-farmer livelihoods. Since 2006/07 the research focus of the CIAT Tropical Forages Program was further refined and includes the adaptation of forages to climate change and their potential contribution to ecosystem services, including the mitigation of greenhouse gas emissions. Within these new developments, species selection is benefiting from the broad diversity represented in the CIAT forages collection.

Distribution

The basis for effective and efficient utilization of CIAT’s forage germplasm has been, and still is, the production and distribution of germplasm samples for plant introduction work by the Center´s GRU/GRP. Since 1980 a total of 93,222 germplasm samples, representing 14,695 accessions, were distributed to 110 countries. Approximately 41% of these samples went to CIAT’s TPP/TFP. The remainder was distributed to users in Colombia (33%), Brazil (9%), Peru, China, Venezuela (4% each), Australia, Mexico, USA (3% each), and 102 other countries. Approximately 47% of all externally distributed samples went to national agricultural research institutes, 23% to universities, 16% to farmers, with the remainder going to CGIAR centers, NGOs, companies, regional organizations, and other genebanks worldwide (Figure 1). Seed samples were predominantly used for agronomic evaluations (64%), but also for basic research (13%), capacity building (12%) and other purposes such as applied research, genetic improvement and conservation, in alignment with the ITPGRFA and the SMTA. The list of accessions included in each seed shipment is linked to available passport data and more recently to accession-specific Digital Object Identifiers (DOI).

For evaluation trials and on-farm experimentation with accessions that were considered as highly promising by CIAT, its network partners and/or development agencies, seed in larger amounts has been/is being provided by the Tropical Forages Program (Tropical Pastures Program until 1992). Between 1982 and 2014, the TPP/TFP produced and distributed almost 64 tons of grass and legume seeds, either free of charge for research purposes or at cost price for larger quantities, representing a total of 27,325 samples, to 88 countries worldwide.

Diversity in the forage germplasm collection

Basic plant descriptors have been used during both the germplasm multiplication phase by the GRU/GRP and the primary evaluation phase by the TPP/TFP to provide information on phenotypic diversity within a species and subsequent reduction of accession numbers for evaluation (e.g. the formation of core collections). In addition, molecular marker studies have been used to assess the genetic (= intraspecific) diversity and to elucidate species relationships for species of particular interest. On species that are little-known but of interest, basic floral-biology studies have been performed with the objective of optimizing germplasm management and enabling breeding. The main publications resulting from such research are listed below (section Publications).

The need for basic botanical and genetic studies to expand our knowledge about genera and species of forage interest must be stressed. Any future diversity research is recommended to focus on relevance for: (1) enhanced germplasm management and utilization (e.g. identification of duplicates, establishment of core collections); (2) relationships between traits and geographic origin of populations; and (3) identification of genes responsible for particularly important plant traits.

Sharing of knowledge

Some thoughts about the value of the CIAT tropical forages germplasm collection

Having safeguarded the germplasm is a major achievement in view of increasing world-wide genetic erosion due to habitat destruction and land use changes. The very availability of conserved germplasm represents an option value whose potential impact cannot be calculated and should not be underestimated.

Given that the CIAT tropical forages collection is an in-trust collection, held by CIAT on behalf of the countries of origin of the accessions, another incalculable option value is that all accessions stored in the genebank are available to users under an SMTA at any time. In this context, an important potential benefit to the 75 countries of origin of the germplasm conserved at CIAT’s genebank is that it is available for repatriation.

The present report has to content itself with showing the number of released cultivars developed from CIAT’s forages collection. An estimation of the total economic benefits derived from the collection is beyond the possibilities of genebank managers or scientists engaged in developing varieties. For this, field studies are suggested to be necessary, which have to involve resource economists for the assessment of acreages planted to the new cultivars, resulting livestock production increases, benefits to the environment (e.g. soil conservation and improvement) and estimates of increased livelihoods of end users.

Author contributions

R.S.K. contributed to the conception and design of the submitted manuscript. All authors contributed to data gathering and analysis and to the drafting, revision and final approval of the submitted manuscript. The views expressed in this publication are those of the authors and do not necessarily reflect the views of CIAT, now part of the Alliance of Bioversity International and CIAT.

Conflict of interest statement

The Authors declare no conflict of interest.

Supplemental data

Supplemental Table 1: Recent nomenclatural changes of tropical forage species mentioned in this document under their previous names, based on the taxonomy accepted by the USDA Genetic Resources Information Network (GRIN).

Supplemental Table 2: Plant collectors who participated in the collecting missions mentioned in Table 1.