EFFECTS OF DESICCANTS, PACKAGING MATERIALS AND STORAGE PERIODS ON SEED QUALITY AND LONGEVITY DYNAMICS OF THREE INDIGENEOUS FOREST TREE SPECIES

ABSTRACT
This study was carried out to determine the effects of seed desiccants, packaging materials and storage periods on seed quality and longevity dynamics of three very important indigenous forest tree species. The experimental period was December, 2015 to June, 2016. Seed collection was done at the Bobiri Forest Reserve. The desiccation experiment was set up using a Randomized Complete Block Design (RCBD) with three (3) replications for each of the three species. The seed storage experiment was set up using 3 x 6 factorial arrangements in Completely Randomized Design (CRD) with three replications for each of the three species. Seed storage experiment was conducted using six packaging materials (jute, nylon, paper, ziplock bag, airtight bottle and no packaging) with three storage periods (no storage, three months storage and six months storage). Germination percentage, seed vigour, 1000 seed weight, moisture content, seed health analysis, carbohydrate, protein and oil contents were assessed before storage, three and six months after storage. The study revealed that the beads dried the seeds of Pericopsis elata within 2 days, 3 days to dry Sterculia rhinopetala seeds and 12 days to dry G. cedrata, which was much faster than the rest of the desiccants without any deleterious effect on seed quality and longevity. Pericopsis elata and Sterculia rhinopetala showed orthodox seed storage behavior by surviving drying to a lower moisture content hence improving storability when packaged in airtight bottle (3.5%) and ziplock bags (3.5%) storage periods increased. The seed carbohydrates, proteins and oils for Pericopsis elata and Sterculia rhinopetala were maintained in the airtight packaging materials thereby improving seed storability. The dormancy of Sterculia rhinopetala was released by using GA3 with a germination percentage of 96.33%. Moist saw dust significantly extended the life span of the Guarea cedrata seeds for at least 21 days. A total number of nine fungi isolates were identified during storage. The seed viability equations predicted that P. elata and S. rhinopetala seeds could be stored for 200 years and 177 years, respectively, after six months of storage. Seed viability dropped significantly (155 days for P. elata and 79 days for S. rhinopetala) after the accelerated aging test performed on the six-months old seeds. The study concluded that P. elata and S. rhinopetala could best be dried with beads at a faster rate and subsequently stored for a longer period using airtight packaging materials whilst G. cedrata, could be stored in a moist saw dust.


CHAPTER ONE
1.0 INTRODUCTION
Globally, the significance of tropical forests is now well understood by scientists, politicians and people of all races (Wagner and Cobbinah 1993; Goldsmith 1998; Verweij 2002). Tree planting is undoubtedly, known to be an effective measure to protect the climate and mitigate climate change. Trees sequester the greenhouse gas carbon dioxide, counteract soil erosion and desertification (Grainger 1993). Trees act as "carbon sinks" and absorb carbon from the air and change it into plant material. That means that to a large extent, planting trees reduces greenhouse gases in the atmosphere and significantly limit the rate at which the ozone layer is depleted. Goods and services obtained from forests sustain human life. Many forests serve as valuable biodiversity reservoirs. They maintain the fertility and stability of agricultural lands, protecting the natural watershed, serve as homes for countless wildlife, and habitats for some cultures and communities. To be more precise, forests are natural assets of huge importance (SCBD, 2009).

At an alarming rate, however, forests are disappearing nearly one percent a year in sub-Saharan Africa (FAO, 2003), regardless of the many reforestation and conservation activities. Apart from the major widespread environmental problems which include global warming, flooding, food insecurity and loss of biological diversity, there is also widespread concern for the 1.5 to 2 billion people who depend on trees for livestock fodder, fruits, local construction, cooking and heating fuel (Bonner, 1992). The World Conservation Union (IUCN, 2008) UNEP WCMC (2001) estimated that about 2000 tropical tree species in Africa are considered to fall into the categories of being „near threatened‟ to „critically endangered‟.

High quality tree seeds are needed to support both reforestation and the in and ex-situ conservation of forest genetic resources (Schmit, 2000). There is therefore the greatest need to restore degraded areas to improve their productive capacity, environmental functions, and bio-diversity value (Parrotta, 2002). Persistent physical, chemical, and biological factors are the major barriers that impede forest regeneration, these severely degraded areas need human intervention to initiate recovery. Among the many ecological restoration methods, planting of tree seedlings have been identified as one of the effective measures to reforest degraded lands (Lamb et al. 2005).

Annually, about one million hectares (2.47 million acres) in the tropics are planted in tree seedlings, but only a small percentage is indigenous (Bonner, 1992). According to Sacande et al. (2004) information about the potential of indigenous species and the availability of their seeds and seedlings are insufficient. Access to seeds and seedlings come with seed handling and storage problems, which limit the use of many high value indigenous trees in tree planting and conservation programmes (Sacande et al. 2004). Furthermore, tropical forest seeds which show orthodox seed storage behaviour have storage and dormancy related issues which adversely affect their storability and seed quality. Such seeds quickly lose their viability and vigour before the next planting season due to improper drying methods, storage/packaging materials and poor storage conditions. Longer seed storage durations also facilitate seed deterioration and reduce seed longevity. The three selected important economic indigenous species for this study are; Peripcopsis elata (Kokrodua) which is an endangered species (IUCN, 2008), Sterculia rhinopetala (Wawabima) and Guarea cedrata (Kwabohoro) which have been described as vulnerable, according to the IUCN Red List of Threatened Species (IUCN, 2001). These species therefore require urgent conservation attention.

It is an undeniable fact that, the starting material for reforestation is seed. It is also the most useful material for plant conservation purposes. Very high quality tree seeds are required for Ghana to reach the target of the Forest Plantation Strategy launched in 2013. This Programme was aimed at planting many hectares of forest each year throughout the country up to the year 2050, with vigourous indigenous and exotic tree species (Ghana Forestry Commission, 2013). From the foregoing, if indigenous species are to be used in afforestation and conservation programmes, it is important to gather relevant scientific knowledge on their seed physiology, identify the appropriate responses of their seeds to desiccation, dormancy breaking methods, storage potential, as well as their seed health improvement techniques. The use of beads, silica gel, calcium chloride, charcoal and rice have been widely used on agricultural seeds with quite an appreciable success (Probert, 2003; Rao et al., 2006; Hay et al., 2012) but scanty research information is reported on tree seeds . Storage life of seeds (longevity) has also been improved by using different packaging materials like jute, nylon, paper bags and airtight containers. There is therefore the need to conduct research on the effects of desiccants, packaging materials and storage periods on seed quality and longevity dynamics of these species. The study primarily is aimed at contributing to scientific information on the effects of seed desiccants and storage packaging materials on seed quality and longevity dynamics of three indigenous forest tree species.

The specific objectives of the study were:
i. To determine the effects of seed desiccants on seed physical quality and chemical characteristics

ii. To determine the interactive effects of packaging materials and storage periods on seed quality and proximate composition

iii. Evaluate the most effective dormancy breaking methods and moist storage on Sterculia rhinopetala and Guarea cedrata seeds respectively.

iv. To predict the longevity of the species using the Improved seed Viability Equation

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Item Type: Ghanaian Project Material  |  Attribute: 110 pages  |  Chapters: 1-5
Format: MS Word  |  Price: GH50  |  Delivery: Within 30Mins.
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