A Systematic Review of Perennial Staple Crops Literature Using Topic Modeling and Bibliometric Analysis

PLoS One. 2016 May 23;11(5):e0155788. doi: 10.1371/journal.pone.0155788. eCollection 2016.


Research on perennial staple crops has increased in the past ten years due to their potential to improve ecosystem services in agricultural systems. However, multiple past breeding efforts as well as research on traditional ratoon systems mean there is already a broad body of literature on perennial crops. In this review, we compare the development of research on perennial staple crops, including wheat, rice, rye, sorghum, and pigeon pea. We utilized the advanced search capabilities of Web of Science, Scopus, ScienceDirect, and Agricola to gather a library of 914 articles published from 1930 to the present. We analyzed the metadata in the entire library and in collections of literature on each crop to understand trends in research and publishing. In addition, we applied topic modeling to the article abstracts, a type of text analysis that identifies frequently co-occurring terms and latent topics. We found: 1.) Research on perennials is increasing overall, but individual crops have each seen periods of heightened interest and research activity; 2.) Specialist journals play an important role in supporting early research efforts. Research often begins within communities of specialists or breeders for the individual crop before transitioning to a more general scientific audience; 3.) Existing perennial agricultural systems and their domesticated crop material, such as ratoon rice systems, can provide a useful foundation for breeding efforts, accelerating the development of truly perennial crops and farming systems; 4.) Primary research is lacking for crops that are produced on a smaller scale globally, such as pigeon pea and sorghum, and on the ecosystem service benefits of perennial agricultural systems.

Publication types

  • Comparative Study
  • Review
  • Systematic Review

MeSH terms

  • Bibliometrics*
  • Cajanus
  • Crops, Agricultural*
  • Databases, Bibliographic*
  • Models, Theoretical
  • Oryza
  • Secale
  • Sorghum
  • Triticum

Grant support

This study was funded by the Bill and Melinda Gates Foundation (http://www.gatesfoundation.org/), grant: “Perennial grain crops for African smallholder farming systems.” The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.