Content of neutral lipids and fatty acid composition of the oil palm seeds (Elaeis guineensis Jacq.) during germination Christian Siadjeu1*, Georges Frank Ngando-Ebongue2, Joseph Martin Bell1, Hermine Bille Ngalle1, Godswill Ntsomboh Ntsefong2 1Department 2
of plant biology, Faculty of Science, University of Yaounde 1, P.O. Box 812, Yaounde, Cameroon IRAD, Centre for Oil Palm Research of La Dibamba, P.O. Box 243, Douala, Cameroon
* Corresponding author. Email:
[email protected], Tel: +237 675 038 414.
Introduction
Objective The main objective of this study was to specify the minimum duration of preheating for optimum dormancy and secondly to assess the impact of physical parameters of seeds and fat reserves content and composition on the induction of germination.
Materials and methods Plant material Seeds were constituted by eight genotypes of improved commercial hybrid seeds divided into two types: tolerant to Fusarium (C1001F and C2301F) and sensitive to Fusarium called normal or standard (C1001, C2301, C2501, C2001, C2101 and C1501). Seeds germination Seeds were germinated following the method described by Corrado & Wuidart (1990). For each genotype, three independent sets of 600 seeds were constituted.
Ten seeds from each repetition were weighed, then crushed and kernels obtained (10) were also weighed. Kernels were dried in the oven at 105 °C for 24h in order to determine the moisture content. Neutral lipids content Neutral lipids were extracted by the Soxhlet method with hexane as extraction solvent. The content was calculated from the weight of the sample before and after delipidation.
af
ad ad ad abcd abcd
60
abcd
ad ad ad abd abcd abcde
abcde
bcdefg bcdef ce
bcde
de
40
e
20
C2501 C2301F C2301 C1001 C1001F C2101 C2001 C1501 C2301F C2301 C1501 C2001 C1001 C2101 C1001F C2501 C2501 C2101 C1001F C1001 C2001 C2301 C1501 C2301F
0
40
60
80
Genotype * preheating time
Fig.3. Effect of genotype*preheating time on germination rate. Values followed by the same letter are significantly different at the 5% level (Newman-Keuls test).
Effect of physical and chemical parameters of seeds on germination
Fig. 1. Gas chromatograph (Thermofisher)
Data collection and analysis Statistical analyzes were performed using SPSS 9.0 software. The incidence of physical and chemical parameters of seeds on the germination process was assessed through multivariate analysis of variance (MANOVA) with P 0.05) the germination rates (Table 1). Table 1. MANOVA of the effect of FAs composition on the germination rate
Results Effect
Effect of preheating duration on the germination rate The germination rate increased with the preheating time (Fig. 2). Our results showed that 60 days was the optimum preheating duration of oil palm seeds.
C8:0 C10:0 C12:0 C14:0 C16:0 C18:1
100 b
Germina- Lambda de tion day Wilk 0 5 0 5 0 5 0 5 0 5 0 5
0,19 0,37 0,19 0,10 0,22 0,13 0,67 0,10 0,20 0,16 0,16 0,15
F
Error df
P
1,20 0,49 1,25 2,68 1,01 1,99 0,14 2,61 1,14 1,50 1,53 1,61
2,00 2,00 2,00 2,00 2,00 2,00 2,00 2,00 2,00 2,00 2,00 2,00
0,53 0,80 0,51 0,30 0,58 0,38 0,98 0,31 0,54 0,46 0,45 0,44
b 80
The change in the weight of the seeds, the weight of the kernel, the embryo weight and the content of neutral lipids between the end of preheating (day 0) and the end of soaking (5 days) didn’t affect significantly (P>0.05) the germination rate.
a 60
40
20
0 40
60 Preheating time (days)
80
Fig. 2. Germination rates according to the preheating time.
Assessment of physical parameter
Germination rate (%)
The methylated FAs were analyzed using a gas chromatograph (GC) (Fig.1).
80
a ag
ag abc
Fat acids analysis
Germination rate (%)
Since 2006, the oil palm (Elaeis guineensis Jacq.) is the most important oil crop in the world (Anonymous, 2007). The worldwide demand for palm oil is estimated at 230 000 000 mt in 2050 for a population of 9.2 billion inhabitants (Rival, 2010). Thus, the production of good quality seeds is required for the implementation of new plantings (Bell, 2000). However, the germination process of seeds (10-12 months) is long and costly (Beugré et al., 2011). During germination, a lipase catalyses the release of fatty acids (FAs) from triacylglycerol stored within oil bodies. The released FAs are converted into sugars, used by the embryo to become a seedling with a photosynthetically active root system and leaves (Graham, 2008). Thus, the content of fat may affect the germination process.
100
Values followed by the same letter are significantly different at the 5% level (Newman-Keuls test).
Effect of genotype*preheating time on the germination rate The seeds of genotypes C2501, C2301, C2301F preheated for 40 days gave 91.19%, 83.83% and 73.42% germination rates respectively, values which were not significantly different from those of the same seeds preheated for 60 and 80 days (Fig.3).
Conclusion 60 days preheating time was considered as optimal duration for oil palm seeds, though some genotypes (C2501, C2301 and C2301F) also performed well after 40 days. The content of neutral lipids of the seeds, the fatty acid composition nor physical parameters of seeds did not significantly affect germination rates. Further investigations will be carried out regarding the impact of triglycerides composition and the activity of the germination lipase on germination rates.
