COMPARATIVE INVESTIGATION OF THE GERMINATION AND EARLY GROWTH PERFORMANCE OF TWO AGROFORESTRY TREE SPECIES IN THE NURSERY

ABSTRACT

The increasing demand for sustainable land-use systems and environmental conservation has intensified interest in agroforestry tree species with economic, medicinal, and ecological importance. This study comparatively evaluated the germination potential and early growth performance of two agroforestry tree species, Annona muricata and Annona reticulata, under nursery conditions. Seeds of Annona reticulata were collected from mature trees within Benin City, while fruits of Annona muricata were sourced from New Benin Market, Edo State, Nigeria. The experiment was conducted at the Department of Forestry and Wildlife nursery, Faculty of Agriculture, University of Benin, Nigeria. A total of 410 seeds were sown in sterilized river sand-filled polyethylene bags arranged in a completely randomized design. Germination parameters such as germination percentage, germination period, seedling height, collar diameter, stem diameter, and number of leaves were assessed weekly over the study period.

Results showed significant variation between the two species in terms of germination and seedling growth performance. Annona muricata recorded superior germination percentage (69.2%) compared to Annona reticulata (4.95%). Furthermore, Annona muricata demonstrated more vigorous early seedling growth, including greater plant height, leaf production, and stem development. The poor germination performance observed in Annona reticulata may be associated with seed dormancy, seed viability issues, or environmental conditions affecting germination. The findings indicate that Annona muricata possesses greater adaptability and nursery establishment potential under the prevailing environmental conditions of the study area.

The study highlights the importance of species selection and nursery management practices in agroforestry development programmes. It further recommends improved pretreatment methods and silvicultural techniques to enhance the germination performance of Annona reticulata. The research contributes valuable information for sustainable agroforestry practices, biodiversity conservation, and nursery management in tropical forestry systems.

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

Forests and trees play a critical role in environmental sustainability, climate regulation, biodiversity conservation, and socioeconomic development. They provide numerous ecological services such as carbon sequestration, erosion control, air purification, temperature regulation, watershed protection, and habitat preservation for wildlife species (Nair, 1993). In addition to their environmental functions, trees also contribute significantly to human livelihoods through the provision of timber, fuelwood, medicine, fruits, fibres, fodder, and other non-timber forest products.

Globally, increasing environmental degradation, deforestation, desertification, and climate change have heightened the need for sustainable land management practices. Agroforestry has emerged as one of the most effective land-use systems for promoting environmental conservation while improving agricultural productivity and rural livelihoods. Agroforestry involves the deliberate integration of trees, crops, and sometimes livestock within the same land management unit for economic, ecological, and social benefits (World Agroforestry Centre, 2010).

Unlike conventional agricultural systems, agroforestry promotes biodiversity, enhances soil fertility, reduces erosion, improves microclimatic conditions, and contributes to food security. It also provides opportunities for sustainable income generation through the cultivation of multipurpose tree species. Consequently, the successful establishment and management of tree seedlings in nurseries are fundamental to agroforestry development programmes.

Nursery practices are essential components of forestry and agroforestry operations because they determine the survival and performance of seedlings after transplanting. Seed germination and early seedling growth are among the most important stages in tree development. Successful germination ensures adequate seedling establishment, while vigorous early growth enhances adaptability, survival rate, and field performance of tree species.

The genus Annona belongs to the family Annonaceae and comprises several tropical fruit tree species valued for their nutritional, medicinal, and economic importance. Among these species are Annona muricata (soursop) and Annona reticulata (custard apple), both of which are widely recognized for their edible fruits, medicinal properties, and suitability for agroforestry systems.

Annona muricata is highly valued for its sweet, aromatic fruits and medicinal applications, while Annona reticulata is known for its adaptability to tropical environments and nutritional benefits. These species possess considerable potential for integration into compound farming, home gardens, and agroforestry systems due to their moderate canopy structure, economic value, and environmental benefits.

Despite their importance, limited information exists regarding the comparative germination behaviour and nursery growth performance of these two species under similar environmental conditions. Seed germination in many tropical tree species is often affected by factors such as seed viability, dormancy, moisture availability, substrate conditions, and genetic characteristics. Understanding the germination requirements and early growth responses of agroforestry tree species is therefore essential for developing effective propagation and nursery management strategies.

This study was therefore undertaken to comparatively investigate the germination capacity and early seedling growth of Annona muricata and Annona reticulata under nursery conditions with a view to identifying the species with better nursery establishment potential for agroforestry development.

1.2 Statement of the Problem

The increasing need for sustainable agroforestry systems has created demand for tree species that can establish rapidly, adapt to varying environmental conditions, and provide multiple ecological and socioeconomic benefits. However, poor seed germination and weak seedling establishment remain major constraints affecting the propagation and large-scale cultivation of many tropical tree species.

Several agroforestry tree species exhibit inconsistent germination behaviour due to seed dormancy, poor seed viability, inadequate nursery practices, and environmental stress conditions. In particular, limited scientific information is available regarding the comparative nursery performance of Annona muricata and Annona reticulata under tropical nursery conditions.

The absence of adequate knowledge on their germination characteristics and early growth performance limits effective species selection for agroforestry and reforestation programmes. In addition, poor nursery establishment may discourage farmers, foresters, and agroforestry practitioners from adopting these species despite their economic and medicinal importance.

Furthermore, environmental challenges such as deforestation, land degradation, and climate change have increased the need for multipurpose tree species capable of supporting sustainable land-use systems. To achieve this, there is a need to evaluate suitable tree species with high germination success and vigorous seedling growth.

This study therefore seeks to assess and compare the germination capacity and early growth performance of Annona muricata and Annona reticulata in the nursery in order to provide scientific information for improved agroforestry and nursery management practices.

1.3 Aim of the Study

The main aim of this study is to comparatively evaluate the germination and early growth performance of two agroforestry tree species, Annona muricata and Annona reticulata, under nursery conditions.

1.4 Objectives of the Study

The specific objectives of the study are to:

1. determine the germination percentage of Annona muricata and Annona reticulata seeds under nursery conditions;
2. compare the germination period and germination rate of the two species;
3. evaluate the early seedling growth performance of the species using parameters such as height, stem diameter, collar diameter, and number of leaves;
4. assess the adaptability of the two species to nursery conditions; and
5. identify the species with better potential for agroforestry establishment and sustainable tree planting programmes.

1.5 Research Questions

The study seeks to provide answers to the following research questions:

1. What is the germination percentage of Annona muricata and Annona reticulata under nursery conditions?
2. Is there any difference in the germination rate of the two species?
3. Which of the two species exhibits superior early seedling growth performance?
4. How adaptable are the species to nursery environmental conditions?
5. Which species is more suitable for agroforestry development programmes?

1.6 Research Hypotheses

Null Hypothesis (H?)

There is no significant difference in the germination and early growth performance of Annona muricata and Annona reticulata under nursery conditions.

Alternative Hypothesis (H?)

There is a significant difference in the germination and early growth performance of Annona muricata and Annona reticulata under nursery conditions.

1.7 Significance of the Study

This study is significant because it provides valuable scientific information on the germination behaviour and early growth characteristics of two economically important agroforestry tree species. The findings will be useful to foresters, nursery managers, agroforestry practitioners, researchers, farmers, and environmental conservation agencies.

The study will assist nursery operators in selecting suitable tree species with better germination performance and seedling vigour for large-scale propagation. It will also contribute to improving nursery management techniques and seed handling practices for tropical tree species.

Furthermore, the research will promote sustainable agroforestry development by identifying species with high adaptability and growth potential under tropical conditions. The successful propagation of these species can enhance biodiversity conservation, food security, climate change mitigation, and environmental restoration programmes.

Academically, the study will serve as a useful reference material for students and researchers in forestry, agroforestry, environmental science, horticulture, and plant science.

1.8 Scope of the Study

The study focuses on the comparative investigation of the germination and early growth performance of Annona muricata and Annona reticulata under nursery conditions. The research evaluates germination percentage, germination duration, seedling height, stem diameter, collar diameter, and leaf production over the study period.

The experiment was conducted within the nursery unit of the Department of Forestry and Wildlife, Faculty of Agriculture, University of Benin, Nigeria.

1.9 Justification of the Study

The growing importance of agroforestry systems in addressing environmental and socioeconomic challenges necessitates the identification of suitable multipurpose tree species for sustainable land management. Annona muricata and Annona reticulata possess considerable economic, nutritional, and medicinal values and are suitable for agroforestry integration.

However, poor understanding of their germination characteristics and nursery establishment requirements may limit their utilization in afforestation and agroforestry programmes. This study is therefore justified because it provides empirical data that can improve propagation strategies and encourage wider cultivation of these species.

The research also supports efforts toward biodiversity conservation, sustainable agriculture, and climate-resilient agroforestry systems in Nigeria and other tropical regions.

1.10 Definition of Terms

Agroforestry

Agroforestry is a sustainable land-use system that integrates trees, crops, and sometimes livestock on the same piece of land for ecological and economic benefits.

Germination

Germination refers to the process by which a seed develops into a seedling under favourable environmental conditions.

Nursery

A nursery is a controlled environment where seeds and seedlings are raised and managed before transplanting to the field.

Seedling Vigour

Seedling vigour refers to the strength, health, and growth performance of young plants during early developmental stages.

Silviculture

Silviculture is the science and practice of establishing, managing, and cultivating forest trees for various purposes.

Biodiversity

Biodiversity refers to the variety of living organisms within an ecosystem, including plants, animals, and microorganisms.

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