Improving Agroforestry in Latin America with the Versatile Tree Genus Inga

Summary:
The student will contribute to a funded project using experimental and observational approaches to determine the best Inga species for agroforestry, while developing their own projects on specific species of Inga.

Project Background:
Tropical forest soils in the Amazon and many other parts of Latin America are generally nutrient-poor and unsuited to long-term agricultural use. Land converted to agriculture by cutting and burning natural vegetation tends to remain productive for only a few years, necessitating continual advance of the agricultural frontier. Agroforestry, which incorporate trees into crop systems, has been shown to make a dramatic impact on the maintenance and restoration of long-term productivity in agricultural landscapes, including degraded and abandoned land, and are well suited to use by poor rural smallholders. They can provide major benefits through enhanced livelihoods and food security.

Inga is a diverse genus of trees from the legume family, found across the humid tropics of Latin America. These fast- growing trees are able to capture nitrogen from the atmosphere and fertilise the soil around them. They can be grown in poor, degraded soils, out-competing weeds and invasive species. The value of native trees, including Inga, within agroforestry systems, where they are planted to provide a nurturing environment for crops, has been amply demonstrated by a number of projects, and is gaining momentum. However, most such systems have been developed around a limited genetic stock of a single species, Inga edulis, yet it performs best under a limited range of conditions and other Inga species are likely to provide equal if not greater benefits outside of this range.

Emerging techniques in genetics offer the potential for rapid identification of species and genotypes of Inga with similar ecological characteristics, thus facilitating fast-tracking of appropriate candidates into field trials. The overall project will apply state-of-the-art genetic approaches to complete a thorough analysis of the genus, focusing primarily on species in the Brazilian Amazon, identifying the most suitable species for agroforestry systems.

The PhD student will contribute to this overall project, which is funded by the UK Biotechnology and Biological Sciences Research Council, while developing their own specific project within this framework. Depending on the student’s interests, this project could focus more on the ecophysiology of Inga species as it relates to their agroforestry potential, to the delivery of agroforestry technology to local communities or another topic within the broad remit of improving the use of Inga in agroforestry.

Potential Key Research Questions:
1) What are the best Inga species for agroforestry in terms of growth potential, nitrogen fixation and foliage production?
2) Can genomic approaches be used to predict a priori the potential of a given Inga species for agroforestry, given the difficulty of field trials for all 300 species in the genus?
3) How can knowledge of Inga species utility for agroforestry best be transferred to relevant stakeholders and smallholders in the field?

Methodology and Training:
The student has the potential to acquire skills in 1) field methods in botany and plant growth trials, 2) molecular laboratory methods, 3) data analysis in the R statistical environment, 4) scientific writing for both grant applications and journal articles, 5) scientific presentation skills, and 6) inter-institutional and inter-cultural collaboration and networking.
The student will gain experience in tropical field botany and working with collaborators from different countries during at least one field expedition to Brazil. The student will be trained in scientific presentation in order to give presentations at national and international conferences. Finally, the student will be encouraged to and helped in applying for external grant funding and in publishing his or her work in scholarly journal articles.

Supervisors:
Dexter has a long track record in studying the focal tree genus Inga, as well as general expertise in tropical plant ecology and botany. He has co-supervised 5 PhD students to completion and currently has 4 primary-supervised PhD students and 1 postdoctoral researcher in his group. Toby Pennington, of the University of Exeter, also has a long track record of studying the agroforestry systems and the genus Inga, and has deep expertise in tropical plant evolution and systematics. He has supervised 22 PhD students to completion, and currently has a research group of three PhD students and two postdocs.