JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE)

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1 JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 47 RESEARCH ARTICLE Modeling the Effect of Storage Duration on Germination Percentage of the Seeds of Azadinrachta Indica A. Juss, Conocarpus Lancifolius Engl & Diel and Sterculia Setigera Delile Hisham M. M.Tahir, * 1 ; Abbas M. A. Abd Alla 2,; Sayda M. Mohamed 3,. 1* Hisham M. M. Tahir College of Natural Resources and Environmental Studies (CNRES), University of Bahri, Sudan (hisham-7777@hotmail.com,). 2 Abbas M. A. Abd Alla Forests at Forests National Corporation (FNC), Sudan. 3 Sayda M. Mohamed National Tree Seed Research Centre (NTSRC), Soba, Sudan. (Received: August 09, 2013; Accepted: November 14, 2013) Abstract- This work depended on data obtained from an experiment to study the effect of storage temperature, packing method and storage duration on the germination percentage of seeds of Azadirachta indica, Conocarpus lancifolius and Sterculia setigera. In that study, the analysis of variance revealed that the only significant effect was that of storage duration. This present work is a further statistical analysis to examine the relationship between storage duration and germination percentage of the seeds of the three species. The mean germination percentages, averaged over all levels of packing methods and storage temperatures, were obtained against storage duration for each of the three species. Regression models of germination percent on storage duration were built for the three species. The curve estimation procedure of the SPSS (Version18) statistical package was used in building of models. The three regression models depicted a cubic relationship according to the best fit indicated by the most significant coefficient of determination (R 2 ). Index Terms- Modeling, Germination percent, Storage duration. T I. INTRODUCTION he propagation of Azadirachta indica (Neem) from seed is hampered by its short storage longevity [1]. Neem seeds do not retain their viability very long and have to be sown within 2 or 3 weeks after harvest [2]. Seeds of Conocarpus lancifolius (Damas) have a low initial germination percentage of 25 [3]. A graph drawn for germination percentage against storage duration [4] shows that germination percentage of seeds falls with the lapse of time. This means that the low initial germination percentage of Damas will be negatively affected by storage duration. Seeds of these two species together with seeds of Sterculia setigera, are The general linear model procedure was used in the analysis of variance (ANOVA), followed by Duncan s Multiple Range considered difficult seeds by the Standards of Kew Botanical Gardens, either because of their initial germination percentage or because they lose their viability with lapse of time [5]. Study of the relationship between storage duration and germination percentage of seeds was studied by many researchers [6] [7] [8] [9] [10]. They arrived at equations which link the two variables through regression analysis. Walters et al. [4] determined graphically a sigmoid relationship between germination percentage and storage duration. The objective of this statistical analysis was to study the relationship between germination percentage and storage duration for each of the three species and to find out what is the model which can best fit this relationship. II. MATERIALS AND METHODS The experiment was conducted at the National Tree Seed Research Centre at Soba (longitude 32⁰ 30 E and Latitude 15⁰ 37 N) Sudan. The seeds of Azadirachta indica and Conocarpus lancifolius were collected from mother trees at Soba. Those of Sterculia setigera were collected from naturally growing trees at El Garri (Longitude 34⁰ 23 E and Latitude 11⁰ 33 N). The experiment included two factors; namely, storage temperature of seeds which was studied at two levels: 30 ⁰C and 12 ⁰C; and packing method of seeds which was studied at two levels: sealed (airtight) and perforated (ventilated) polythene bags. Each of the four combinations of the two factors was replicated four times. The time factor (duration of storage) was considered during collection of the data. The SAS statistical package was used in the ANOVA and the mean comparison. Test which was applied to the mean comparison of the significant effect. The mean germination percentages,

2 dimension1 Cubic JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 48 averaged over all levels of packing methods and storage temperatures, were obtained against storage duration for each of the three species. Regression models of germination percent on storage duration were built for the three species. The statistical package PASW (SPSS) Version 18 for windows was used for the statistical analysis to build the regression models. Curve estimation procedure of the package was adopted. III. RESULTS AND DISCUSSION Effect of the treatments and their interactions According to the ANOVA, the only significant effect on germination percentage of the three species was that of the storage duration. The finding of the mean comparisons using Duncan s Multiple Range Test is shown in Table1. Table 1: Effect of storage duration averaged over all levels of temperature and packing method on germination percentage (*) Azadirachta indica Conocarpus lancifolius Sterculia setigera Duration (Months) Mean Germination% Duration (Months) Mean Germination% Duration (Months) Mean Germination% a a a b c b c b c * Means in the same column followed by the same letter are not significantly different according to Duncan s Multiple Range Test (α=0.05) Relationship between germination percent and storage duration All the results showed cubic relationships between the germination percent and storage duration of seeds with significant coefficients of determination (R2). This is seen in the summary tables (Tables 2.1, 2.2 and 2.3) and the scatter diagrams (Figures 1, 2, and 3). Dependent Variable: Germination Table (2.1): Model Summary and Parameter Estimates (Azadirachta indica) Equation Model Summary Parameter Estimates R Square F df1 df2 Sig. Constant b1 b2 b The independent variable is Duration.

3 dimension1 Cubic JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 49 Fig.1: Relationship between germination% and storage duration (months) of Azadirachta indica seeds Dependent Variable: Germination Table (2.2): Model Summary and Parameter Estimates (Conocarpus lancifolius) Equation Model Summary Parameter Estimates R Square F df1 df2 Sig. Constant b1 b2 b The independent variable is Duration.

4 dimension1 Cubic JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 50 Fig.2: Relationship between germination% and storage duration (months) of Conocarpus lancifolius seeds Dependent Variable: Germination Table (2.3): Model Summary and Parameter Estimates (Sterculia setigera) Equation Model Summary Parameter Estimates R Square F df1 df2 Sig. Constant b1 b2 b The independent variable is Duration.

5 JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 51 Fig.3: Relationship between germination% and storage duration (months) of Sterculia setigera seeds A curve showing the germination percent against time for one seed lot under constant storage conditions would be a sigmoid curve [4]. Sigmoid data can best be fit with a cubic model [11]. The foregoing two statements exactly coincide with the results of this study. The three curves of germination percent against storage duration in months which were obtained for Azadirachta indica, Conocarpus lancifolius and Sterculia setigera; are sigmoid. The three curves are best fitted by cubic models. IV. CONCLUSION AND RECOMMENDATIONS The main finding of this study is that quantification of the effect of storage duration on germination percentage of seeds could be obtained with an acceptable level of accuracy using empirical regression models. Further research work could be conducted to: - Study the effect of storage duration on the germination percentage other tree species of economic importance. - Build regression models to quantify the effect of storage duration on the germination percentage of these tree species. References [1] Schandle, M. (1998). A multi factorial study of conditions influencing neem (Azadirachta indica) seed storage longevity. Seed Sci. Res. 8: pp [2] NAS. (1980). Fuelwood Crops: Shrub and Tree species for Energy Production. Volume1. 237pages. [3] NAS. (1983). Fuelwood Crops: Shrub and Tree species for Energy Production. Volume2. 92pages. [4] Christina Walter, Lana M. Wheeler and Judith, M. Grutenhuis. (2005).Longevity of seeds stored in a gene bank: species characteristics. Seed Sci. Res. 15 (1): pp [5] [6] Pritchard, H.W. and Dickie, J. B., (2003), Predicting Seed Longevity: the use and abuse of seed viability equations, pp In: R.D Smith, J.D Dickie, S.H. Linington, H.W Pritchard &. R.J Probert

6 JOURNAL OF FOREST PRODUCTS & INDUSTRIES, 2013, 2(6), 47-52, ISSN: (PRINT), ISSN: X (ONLINE) 52 (Eds) Seed conservation: turning science into practice. Royal Botanic Gardens, Kew, UK. [7] Ellis, R.H. and Roberts, E.H. (1980). Improved equations for the prediction of seed longevity, Annals of Botany 45, [8] Hay, F.R., Mead A., Manger, K. and Wilson F.J. (2003). One-step analysis of seed storage data and the longevity of Arabidopsis thaliana seeds, Journal of Experimental Botany 54 (384), [9] Cromarty, A.S. Ellis, R.M. & Robert, E.H The Design of Seed Storage Facilities for Genetic Conservation, IBPGR, Rome [10] Flynn, S. and Turner, R. M. (2004). Seed Viability Equation: Viability Utility (release 1.0, September 2004) [11] Locascio, J. J. and Atri, A. (2011). An overview of longitudinal data analysis methods for neurological research, Dementia and Geriatric Cognitive Disorders Extra. 1 (1): pp /