Conserving Open Natural Pollination Safeguards Jatropha Oil Yield and Oil Quality

Abstract

The high oil content and suitable fatty acid composition of the seeds are two arguments to promote Jatropha curcas L. as a promising biodiesel crop. For seed yielding crops as J. curcas, it can be expected that successful pollination is a key process affecting oil yield and oil quality. Field experiments were conducted in Zambia to study the effects of different pollination treatments (autonomous autogamy, open natural, open pollen supplemented, self, and cross-pollination) on seed morphology, seed oil content (g), seed oil concentration (%), and oil fatty acid composition of J. curcas in 2-and 5-year-old plantations. For this experiment, 100 inflorescences per plantation were selected. Autonomous autogamy and self-pollination treatments reduced oil yield with 70 and 29 % respectively, compared to open pollination. Cross-and self-pollinations resulted in longer seeds than open pollination but did not affect oil content and concentration. The oil has high unsaturated fatty acid content (80 %) and is composed of nine fatty acids. Pollination treatments had an effect on fatty acid composition of oil from mature trees (5 years old), but had not for 2-year-old trees. The oleic acid content, a determinant fatty acid component for quality biodiesel production was lower for artificial self-pollination (9 % reduction) compared to open pollination. This research demonstrates that overall oil yield and quality are the highest under natural pollination. This shows the importance of safeguarding the quality and effectiveness of open natural pollination. This can be done by enhancing the presence of insects identified as J. curcas pollinators, particularly those pollinators enhancing cross-pollination.

Initial Effects of Fertilization and Canopy Management on Flowering and Seed and Oil Yields of Jatropha curcas L. in Malawi

“…Planting density had effects on flower sex ratio and female flowers number, but this was not demonstrated on seed yield per hectare and final oil yield per hectare. This might be due to the young age of the plants, with smaller seeds and lower number of mature seeds [12,46]. Therefore, long-term experimental observations are needed to evaluate the effects of planting density on J. curcas seed and oil yields.…”

“…The tree can attain 3 to 5 m of height and can be grown as a commercial crop in plantations or on the boundaries of fields as a hedge [8][9][10]. The oil from the seed is a valuable feedstock for bioenergy, which has attracted the interest of investors, scientists, and politicians as a possible substitute for fossil fuel to satisfy world energy demand, reduce CO 2 emissions, and mitigate climate change [11,12].…”