Variation in oil content in Camellia japonica seeds

De Ron, A.M.^1,3*, Salinero M.C.^2,3, Vela, P.^2,3

¹ Misión Biológica de Galicia, Spanish National Research Council (CSIC), El Palacio-Salcedo, 36143 Pontevedra, Spain. * E-mail: amderon@mbg.csic.es
² Estación Fitopatolóxica do Areeiro, Deputación de Pontevedra, Subida a la Robleda s/n, 36153 Pontevedra, Spain.
³ Associated Unit Agroforestry Systems (SA-EFA). Pontevedra, Spain

Introduction

      The genus Camellia is one of 30 included in the family Theaceae and comprises 284 species (Chang and Bartholomew, 1984), two of which have outperformed all others until a few years ago: C.sinensis, from whose leaves tea is obtained, and C. japonica, of great interest as an ornamental plant (Samartín and Pérez, 1984). Today other species are becoming important such as C. grijsii, C. longicarpa, C. maliflora, C. oleifera, C. salicifolia, C. taliensis, C. yuhsienensis and C. yunnanensis: some have been used in Asia for centuries for the production of oils used in both food and cosmetics.
      Very little data is available on the date of the introduction of the first camellias in Europe. The first living camellias documented were exhibited in England in 1739, in the greenhouses of the gardens of Robert James, 8th Lord Petre, at Thorndon Hall (Essex), and were probably brought from China by Jesuit missionaries (Samartín and Pérez, 1988) or by English merchants and sailors (Short, 2005). There are two surviving paintings of these plant; one depicting a red flower and the other a white flower.
      The genus Camellia was introduced into Galicia (NW Spain) in the XIX century (Salinero and Vela, 2003). At first it was mainly cultivated in “Pazos”- palaces - belonging to the Galician nobility, where suitable growing conditions were found: both climate and fertile soil. Currently different species of the genus Camellia (mainly C. japonica) are present in many gardens in the North and Northwest Spain adapted to a wide range of uses, although it is more common to see them as an isolated tree or in groups where various species and cultivars of different flowers give colour for long periods of time (September to May) in the garden. Many experts are surprised to see that in Galicia camellias grow splendidly despite being neglected for long periods of time, while in other regions of Spain or Europe they need constant care is, requiring even the protection of a greenhouse. In general, it is accepted that cold weather and even rain can damage the winter blooms of Camellia species, however both factors benefit growth, and interestingly in several countries, even those less favourable for Camellia cultivation, it is common to use them to form hedges and protective barriers around the edges of gardens, orchards and flower beds.
      In recent years, the number of pests and diseases detected in Camellia has increased considerably. This may be related to the widespread and increasing international trade and the exchange of plant material that has contributed to the spread of pathogens. In addition, the varie environmental conditions in which it develops can also affect the occurrence of pests and diseases (Varela et al., 2003).

      Camellia oil is considered one of the best cooking oils in the world (Huang et al., 2013). Camellia oil, extracted from different species has long been processed as industrial oil, used in the production of cosmetics, soaps, hair oil, medicines and now it is generating interest also as a biofuel source (Lin and Fan, 2011). However, today these plants are grown on a large scale in China and to a lesser extent Japan. Outside Asia, the uses and development process of this camellia oil is unknown. Camellia oil is extracted by pressing the seeds. Its composition is very similar to olive oil, both of which are very beneficial to health. Furthermore, camellia oil has a higher concentration of monounsaturated fatty acids, beneficial to health because it reduces levels of bad cholesterol. The oil can also be used cosmetically in the preparation of shampoos, soaps, creams, etc. The objective of the present work was to analyze the variation in oil content in Camellia japonica seeds from plants growing in different locations of Galicia (NW Spain).

Material and methods

      Seeds of 61 C. japonica plants from different genotypes growing in different locations were analyzed (Table 1). The traits studied were: seed weight (g), number of seeds/100 g, seed oil content (%, g) and oil density (g/ml).

Table 1. C. Japonica cultivars and locations of the seed sampling.

 
 1           2

3          4

Figure 1. Sampling locations. 1: Areeiro, 2: Lourizán, 3: Rubiáns, 4: San Cibrán

      Samples of fruits of were collected in autumn from healthy plants in the different sampling locations. The harvest was carried out when fruits began to split open and the seeds were visible, a phenological stage of fruit development that corresponds to the BBCH stage 88 described for C. japonica (Vela et al., 2013). For each plant, a seed sample of 1 kg was taken and divided into five 200 g subsamples. Oil extraction was performed for each subsample.

Figure 2. Pressing the seeds

Figure 3. Filtering the oil

Results and discussion

      Table 2 displays the results of the traits studied in the 61 C. japonica plants from several genotypes studied in different locations. The seed oil content averaged 20.8 %, with a range of variation from a minimum of 5.5 % in 91-Yosemite at Areeiro-b4 to a maximum of 29.6 % in a plant at Lourizán, which confirms the environmental effects on oil content described in C. reticulata by Huang et al. (2013). This variability in the oil content reflects phenotypic diversity that could be the basis for a selection program to improve the oil content in the C. japonica seeds. Table 3 summarizes the oil content by genotype and location, to support that hypothesis.
      The correlation between seed weight and oil content was not significant for the complete set of plants, but in the subsample of those plants (31) that were richer in total oil content (>0.200 g/seed), the correlation coefficient of -0.428 was highly significant, which means that in rich-oil seeds, seed size has a negative effect on the total oil content.

Table 2. Results of the traits studied in the 61 C. japonica plants analyzed.

Table 3. Oil content by genotype and location in the 61 C. japonica plants analyzed.

Conclusion

      According to these results it is concluded that C. japonica seed oil production displays wide diversity and could be optimized by plant or genotype selection, based in seed traits, and that choice of an appropriate environment could bring further improvements in the seed oil content.

References

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