Some physico-viable properties of Eucalyptus citriodora, Eucalyptus camaldulensis and Eucalyptus cloeziana were determined using their seeds in order to provide a suitable test measure for their viability. The bulk densities of E. citriodora, E. camaldulensis and E. cloeziana were found to be 1.18, 1.13 and 1.14 g cm-3 while their germination capacity on volume basis were 25, 94 and 64 seedlings cm-3, respectively. These could be used in calibration of devices for testing of the viability of these seeds as well as predicting their germination. The light transmissivity of E. citriodora, E. camaldulensis and E. cloeziana were found to be 12.17, 2.00 and 2.66 lux, respectively. This property could be applied in identification of viable seeds of Eucalyptus species.
PDF Abstract XML References Citation
How to cite this article
The identification of most granular seeds depends so much on their physical properties. Eucalyptus is one of the worlds most important and most widely planted genera. It includes more than 700 species and belongs to the family of Myrtaceae which has about 100 genera (Maciel et al., 2010). Many researchers have worked on the on some other aspect of Eucalyptus seedling to reduce its susceptibility to environmental hazards (Khosla and Reddy, 2008). In Nigeria there are various species of Eucalyptus which are E. citriodora, E. camaldulensis, E. cloeziana, E. globules amongst other. One of the trial afforestation located in Kaduna, Nigeria based its research on some Eucalyptus species because of their good provenance (FAO, 1981). In the northern part of Nigeria there has been promulgation for rapid tree planting in order to combat adverse of effect of climate change and environmental degradation such as desertification. Some species of Eucalyptus are also grown in other part of Nigeria due to its resistance to adverse soil and environmental condition. Also, other researchers have worked on several aspects of Eucalyptus which include the chemical composition of their essential oils, their insecticidal and fungicide effects, seed size effects on growth, their interaction with other plants, their interaction with other plants, their strength characteristics (Maciel et al., 2010; Cheng et al., 2009; Somda et al., 2007; Batisha et al., 2008; Kidanu et al., 2004; Olufemi and Malami, 2011). There are various ways of identifying various species of Eucalyptus seeds as well as enabling their uniformity in germination and growth rate in multiple planting. Kumar et al. (2006) applied electrical properties to determine the viability of poppy seeds. Naidu and Jones (2007) showed the effect of seed size of Eucalyptus grandis on its field performance. McRae (2005) also reported the influence of grading on the growth and germination rate of some Eucalyptus species and how it can be applied to precision sowing. The larger seeds were found to have better germination rate due to their greater amount of endosperm reserves that are available during the germination process (Schmidt, 2000). However, some of these seeds are very small; thus it is very difficult to determine their viability without planting. The objective of this study was to determine some physico-viable properties of the seeds of E. citriodora, E. camaldulensis and E. cloeziana as a way of testing their viability before planting.
MATERIALS AND METHODS
Seed preparation: Some seeds of Eucalyptus species (viz., E. citriodora, E. camaldulensis and E. cloeziana) were obtained from Forestry Research Institute of Nigeria/JICA Kaduna house station as shown in Fig. 1-3. The seeds were thoroughly cleaned and screened before conducting the experiment. The seeds were kept under normal room temperature before the experiment. All experiments were carried out under laboratory condition.
Determination of seed bulk density: The bulk densities of the three species of Eucalyptus (i.e., E. citriodora, E. camaldulensis and E. cloeziana) were found by filling a container of specific volume with the seeds after which it was tapped and leveled.
|Fig. 1:||Eucalyptus citriodora seeds|
|Fig. 2:||Eucalyptus camaldulensis seeds|
|Fig. 3:||Eucalyptus cloeziana seeds|
|Fig. 4:||Light transmissivity set up|
The mass of the seeds inside the container was weighed using a digital weigh balance (Denver Instrument XP-300) reading to 0.01 g as conducted by Aremu and Fadele (2011). The ratio of the seed mass to the volume of the container gives the bulk density of the seed as reported by Sugri et al. (2011) in Eq. 1. This was replicated fourteen times for each of the species while their average values were calculated:
Determination of light transmissivity: Light transmissivity is used to indicate the quantity of light that can pass through a material. The set up for the experiment included a light source, a Lux meter and a small transparent container as shown in Fig. 4. The light source was focused at a distance of 9.0 cm from the light receptor with the transparent container being placed on it. The container was loaded with the Eucalyptus species (E. citriodora, E. camaldulensis and E. cloeziana) to 11.60 cm3 of its capacity and leveled; after which the light intensity value was read from the Lux meter. This was replicated for six times for each of the Eucalyptus species. Before this, the radius of the container was measured as 2.80 cm and the seed dept was calculated as 0.471 cm. The experiment was carried in a dark environment to prevent light interference from other source.
Determination of germination capacity: Some seeds of the three Eucalyptus species (viz., E. citriodora, E. camaldulensis and E. cloeziana) were collected from the whole bulk and made to fill up a container having a specific volume of 5.80 cm3, after which it was planted in boxes filled with sharp sand (Franks et al., 1995). This was wet periodically until all the seeds have germinated. The seedlings were subsequently harvested and counted after 11 days. The germination capacity of each Eucalyptus species were found on volume basis by calculating the ratio of the seedling harvested to the seed volume planted respectively for each of the species as given in Eq. 2:
RESULTS AND DISCUSSION
Bulk density of Eucalyptus seeds: The bulk densities mean values of some Eucalyptus seeds namely, E. citriodora, E. camaldulensis and E. cloeziana were found to be 1.18, 1.13 and 1.14 g cm-3 with ranges of 1.16-1.24, 1.10-1.17 and 1.12-1.16 g cm-3, respectively. The value obtained for Eucalyptus species indicated that good portion of their seeds would not float in water and this asserts that their true densities are more than that of water. Most researchers have conducted experiment involving both true and bulk densities with the true density having greater value than the bulk density (Aremu and Fadele, 2011; Balasubramanian, 2001; Baryeh, 2001; Isik and Izli, 2007). This shows that water could be used to for the viability of the seed by dropping them in it. The bulk densities values of each of the Eucalyptus species were subjected to paired sample t-test statistics using SPSS 15 version, by comparing them with one another to determine their level of discrepancy. Eucalyptus camaldulensis compares favourably with E. cloeziana with a significance value greater than 0.05; thus indicating that there is a little difference in their bulk densities. However, the significance values obtained when the bulk density of E. citriodora was compared to that of E. camaldulensis and E. cloeziana were much more less than 0.05; indicating a significant difference in their bulk densities. Figure 5 shows the bulk densities of some Eucalyptus species.
|Fig. 5:||Bulk densities of some Eucalyptus species|
|Fig. 6:||Light transmissivity of some Eucalyptus species|
|Fig. 7:||Germination capacity of some Eucalyptus species|
Light transmissivity of Eucalyptus seeds: The light transmissivity of Eucalyptus seeds namely E. citriodora, E. camaldulensis and E. cloeziana were found to have mean values of 12.17, 2.00 and 2.66 lux, respectively as shown in Fig. 6. The light source was also found to have a value of 2380 lux; indicating that the Eucalyptus seeds are opaque in nature and will allow little or no amount of light to pass through it. E. citriodora has the highest value of light transmissivity because of its seed size which creates pore spaces for light to pass. This was also observed in E. cloeziana seed which is larger than E. camaldulensis and also having higher light transmissivity, even though not as high as that of E. citriodora. This property could be applied in developing a device that can be used to identify viable seed of Eucalyptus.
Germination capacity of Eucalyptus seeds: The mean values of germination capacity for some Eucalyptus seeds (viz., E. citriodora, E. camaldulensis and E. cloeziana) were found to be 25, 94 and 64 seedlings cm-3 with ranges of 23-28, 88-104 and 56-73 seedlings cm-3, respectively. Eucalyptus camaldulensis obviously has the highest value of germination capacity as shown in Fig. 7. It was observed at germination stage that the seedlings of Eucalyptus camaldulensis densely covered the planting area while seedlings of Eucalyptus citriodora sparsely spread over the planting area. Moreover, germination rate of E. camaldulensis was much higher than that of E. citriodora and E. cloeziana while the stalk of E. citriodora is stronger than that of E. camaldulensis and E. cloeziana; and able to withstand water droplet impact during wetting unlike the other two species. The fewer number of seedlings of E. citriodora that germinated could be due its larger volume occupied by its seeds, when compared to E. camaldulensis and E. cloeziana. The circumscribing radius of E. citriodora seed was found to be more than 2.00 mm greater than the other two species and similar to that obtained by Beltrati (1978).
Some physico-viable properties of E. citriodora, E. camaldulensis and E. cloeziana seeds were investigated. The results obtained revealed that the bulk densities and germination capacity of E. citriodora, E. camaldulensis and E. cloeziana seeds have ranges of 1.16-1.24, 1.10-1.17 and 1.12-1.16 g cm-3 and 23-28, 88-104 and 56-73 seedlings cm-3 with their light transmissivity having mean values of 12.17, 2.00 and 2.66 lux, respectively. All these data could be useful testing for the viability of these seeds. However, further research should be conducted on non-viable seeds of these eucalypts for comparison.
The authors will like to thank the Forestry Research Institute of Nigeria for providing all the seeds used for the conduct of this research and the Department of Agricultural Engineering, Federal College of Forestry Mechanization for making their facilities available. Many thanks to the staffs of Forestry Research Institute of Nigeria/JICA Trial Afforestation Kaduna for the assistance rendered during the conduct of the research.
- Aremu, A.K. and O.K. Fadele, 2011. Study of some properties of doum palm fruit (Hyphaene thebaica) in relation to moisture content. Afr. J. Agric. Res., 6: 3597-3602.
- Balasubramanian, D., 2001. PH-postharvest technology: Physical properties of raw cashew nut. J. Agric. Eng. Res., 78: 291-297.
- Baryeh, E.A., 2001. Physical properties of bambara groundnuts. J. Food Eng., 47: 321-326.
- Batish, D.R., H.P. Singh, R.K. Kohli and S. Kaur, 2008. Eucalyptus essential oil as a natural pesticide. For. Ecol. Manage., 256: 2166-2174.
- Beltrati, C.M., 1978. Morphological and anatomical studies of the seeds and seedlings of Eucalyptus citriodora and E. maculata. Rev. Biol. Trop., 26: 213-225.
- Cheng, S.S., C.G. Huang, Y.J. Chen, J.J. Yu, W.J. Chen and S.T. Chang, 2009. Chemical compositions and larvicidal activities of leaf essential oils from two eucalyptus species. Bioresour. Technol., 100: 452-456.
- Franks, P.J., A. Gibson and E.P. Bachelard, 1995. Xylem permeability and embolism susceptibility in seedlings of Eucalyptus camaldulensis Dehnh from two different climatic zones. Aust. J. Plant Physiol., 22: 15-21.
- Isik, E. and N. Izli, 2007. Physical properties of sunflower seeds (Helianthus annuus L.). Int. J. Agric. Res., 2: 677-686.
- Khosla, B. and M.S. Reddy, 2008. Response of Ectomycorrhizal fungi on the growth and mineral nutrition of eucalyptus seedlings in bauxite mined soil. Am. Eurasian J. Agric. Environ. Sci., 3: 123-126.
- Kidanu, S., T. Mamo and L. Stroosnijder, 2004. Eucalyptus-Wheat interaction on Ethiopian nitosols. Agric. Syst., 80: 151-170.
- Kumar, P., S.P. Singh, R. Manohar and J.P. Shukla, 2006. Moisture dependent electrical parameter as an indicator of germination of seed: A case study of poppy seed. Int. J. Agric. Res., 1: 534-544.
- Maciel, M.V., S.M. Morais, C.M.L. Bevilaqua, R.A. Silva and R.S. Barros et al., 2010. Chemical composition of Eucalyptus spp. essential oils and their insecticidal effects on Lutzomyia longipalpis. Vet. Parasitol., 167: 1-7.
- Naidu, R.D. and N.B. Jones, 2007. Effect of seed size on field survival and growth of Eucalyptus in KwaZulu-Natal, South Africa. Southern Hemisphere For. J., 69: 19-26.
- Olufemi, B. and A. Malami, 2011. Density and bending strength characteristics of North Western Nigerian grown Eucaliptus camaldulensis in relation to utilization as timber. Res. J. For., 5: 107-114.
- Somda, I., V. Leth and P. Sereme, 2007. Evaluation of lemongrass, eucalyptus and neem aqueous extracts for controlling seed-borne fungi of sorghum grown in Burkina Faso. World J. Agric. Sci., 3: 218-223.
- Sugri, I., S.K. Nutsugah and J. Yirzagla, 2011. Effect of some seed physical characteristics on viability of pearl millet (Pennisetum glaucum (L.) R. brown). Res. J. Seed Sci., 4: 181-191.