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Jackfruit (artocarpus Heterophyllus Lam.) Diversity in Bangladesh: Land Use and Artificial Selection

RUBY KHAN
Department of Botany, University of Rajshahi, Rajshahi, Bangladesh

NYREE ZEREGA*
Chicago Botanic Garden, Glencoe, IL, USA

SALMA HOSSAIN
Gono University, Savar, Dhaka, Bangladesh

M. I. ZUBERI
Department of Botany, University of Rajshahi, Rajshahi, Bangladesh

Abstract/ Executive Summary:

Jackfruit (Artocarpus heterophyllus Lam.) Diversity in Bangladesh: Land Use and Artificial Selection. Bangladesh is often recognized as a secondary center of diversity for jackfruit (Artocarpus heterophyllus Lam.) and is expected to harbor important genetic diversity of this underutilized tree crop. Unfortunately, genetic erosion is occurring before this rich local resource has been documented and utilized for potential crop improvement. The aim of this study was to carry out a village-based survey and make morphological measurements to document and assess jackfruit diversity across trees associated with a gradient of three locations/habitats (homesteads, public lands, and forest or fallow lands). We also tested the hypotheses that cultivated jackfruit found in homesteads exhibited positive selection pressure for characteristics desirable in the market, and that the tree location reflected its history of origin and human selection. This was accomplished using 28 standardized morphological descriptors and represents the first large-scale assessment (900 trees) of jackfruit diversity in multiple locations (nine villages). Among the descriptors studied, those most closely associated with jackfruit marketability showed a trend for selection among the trees located in homesteads. Both fruits and leaves were larger in plants on homesteads compared to plants in forest/fallow lands, and fruit quality was significantly higher in homestead trees compared to the other two location categories. However, 18.7% and 23.7% of the fruits found on public lands and forest/fallow lands, respectively, were still considered to be of excellent fruit quality and tree vigor was significantly higher in jackfruit in forest/fallow lands compared to the other location categories. The combination of high tree vigor and presence of excellent fruit quality among jackfruit in forest/ fallow lands suggests that the “wild” Bangladeshi jackfruit germplasm, which is considered inferior for market and is being negatively impacted, has valuable genetic diversity to contribute to jackfruit cultivation. Furthermore, sampling across a gradient of habitats may enable the detection of possible trends resulting from domestication pressures.

Keywords: Jackfruit, Artocarpus heterophyllus, Bangladesh, Genetic erosion, On-farm conservation, Underutilized crops.

Location: The district of Tangail of Bangladesh

Start Date:

End Date:

Program Area: Conservation and Biodiversity

Commodity: Jackfruit

Objectives:

This study focuses on assessing morphological descriptors of jackfruit in Bangladesh across a range of locations to better understand jackfruit diversity as well as inform in situ conservation strategies.

Methodology:

STUDY SITE The study was conducted in the district of Tangail of Bangladesh in nine villages where the authors have good rapport with villagers and where jackfruit trees grow widely in villages and forest edges. The villages form a transition from forested areas with very scattered human settlements to densely populated villages away from forest and fallow lands. Land use types include farming (about 50%), forest (20%), and homesteads (15%). The study area falls broadly within the region of semi-deciduous forest dominated by sal (Shorea robusta Roxb. ex Gaertn. f.). This area has a long history of human habitation, so it is not possible to know exactly the past history of land use in areas that are now forest or fallow lands. It is possible that these lands were managed in the past. However, the indigenous people still inhabit the study area and they did little alteration to the forest until the 20th century. The homesteads included in this study represent “settlers” who cleared parts of the forests for croplands and settlements starting in the 20th century. It is likely that the jackfruit and other tree species in and around forests are remnants from before this time. Village Interviews In the selected areas, 120 villagers were asked in unstructured interviews about the history and origin of individual jackfruit trees in their homestead, neighborhood, fallow lands, and in the forest (Table 1). Both males and females of varying ages were surveyed. However, given that many people do not know their age and women are reluctant to answer questions about their age, the exact ages of individuals were not gathered. Villagers were asked questions from a checklist in informal group discussions, regarding a particular tree. In the survey questions, stress was placed on the age and qualitative characteristics of the trees following recommendations from the International Plant Genetic Resources Institute’s “Descriptors for Jackfruit” (IPGRI 2000). They were also asked about fruit quality, taste, and size as well as about their use of jackfruit. This was accomplished by having the group taste the available fruit of the tree they were examining and rank its quality following IPGRI descriptors (2000). Tree vigor was measured following the recommendations of IPGRI (2000) on a three point scale (low, medium, high). Tree vigor was assessed by the first author after she had done a field survey and standardization trial. Assessments of jackfruit trees were made based on three broad location categories: Trees found on small homesteads (known to be intentionally planted by humans), trees found on public land (not known whether or not they were intentionally planted), and trees found away (at least 2/ 3 km) from the homesteads in fallow lands, forests and forest edges (were not planted by the villagers). The three categories will be referred to as “Homestead,” “Village,” and “Forest/Fallow,” respectively. These three location-based categories were used in the present study to assess morphological diversity of jackfruit across a gradient of trees and habitats in a narrow geographic range. Within each category, 300 adult jackfruit trees were chosen randomly from across the nine villages, for a total of 900 trees sampled (Table 1). Assessment of Variation Morphological variation among trees was assessed using jackfruit descriptors from the International Plant Genetic Resources Institute (IPGRI 2000). Descriptors included 20 qualitative and eight quantitative measures of vegetative and reproductive characters (Tables 2 and 3). The qualitative tree characters were measured by observation and drawing upon the knowledge of the local villagers. Quantitative characters were measured in centimeters (Table 3). Statistical analyses were performed using JMP 5.1.2 (SAS Institute, Cary, North Carolina, USA). The quantitative data were analyzed using one-way ANOVA and Principal Components Analysis (PCA). For qualitative data, frequency distribution analyses and chi-square tests were performed.

Source of Information: Economic Botany, 64(2), 2010, pp. 124–136.

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

The current results and villagers’ knowledge base indicate that Bangladesh could harbor wild jackfruit diversity and represent a noncenter or secondary center of diversity. This highlights the need in Bangladesh for A) further documentation and evaluation of jackfruit fruit types, B) development of a subset of representative descriptors for different jackfruit plant and fruit types that will facilitate ease of use by local researchers and farmers, C) identification of preferred jackfruit cultivars, D) molecular assessment of jackfruit diversity in a larger context compared to other regions, and E) establishment of jackfruit germplasm collections as well as participatory on-farm conservation programs. Most of the villagers expressed their willingness to participate in any plant conservation program, but they emphasized that it would have to be part of a well-defined, long-term program with the involvement of the government or non-governmental organizations to insure long-term sustainability.

Knowledge Management: Journal