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Title: Tuber and Inulin production of Jerusalem artichoke (Helianthus tuberosus, L.) under Salinity Stress

item Ferreira, Jorge
item DIAS, NILDO - Federal Rural University Of The Semi-Arid
item Liu, Xuan
item Suarez, Donald

Submitted to: International Congress on Irrigation and Drainage
Publication Type: Abstract Only
Publication Acceptance Date: 10/2/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The major problem with biofuel crops is that they compete with prime agricultural land, water, and are food staples. Jerusalem artichoke is a crop originated in the US that produces inulin-rich tubers, is adaptable to marginal lands and can tolerate saline water. Inulin is a complex sugar (a fructan) that is a source of carbon for biofuels and of non-caloric sugar for the food market targeting products suitable for diabetics. Although the plant has a tremendous potential to produce tons of tubers per hectare when cultivated in saline soils or with recycled saline waters, research with this plant in the United States is almost inexistent in the past 30 years. The crop has been widely researched in China, Europe, and Canada. Our current research in southern California indicates that this crop is suitable for the production of tubers with moderately saline irrigation waters and our results may be also suitable for the Brazilian northeast region, an area afflicted by scarce rainfall and by naturally saline subterranean waters. Plants were irrigated with blended waters of electrical conductivity (ECw) 1.2 (low-salinity control), 3.9, 6.6, 9.3, and 12 dS m-1 (highest salinity) for the whole crop cycle. An increase in salinity from 1.2 to 6.6 dS/m reduced shoot biomass by 37%, but tuber yield only by 11% indicating that plants can be highly productive at ECw = 6.6 dS m-1. However, the highest ECw of 12 dS m-1 caused a 67% decrease in shoot biomass and 47% decrease in tuber yield. When blended and sequential irrigation treatments (low-salinity water followed by high-salinity water at set intervals) were compared, tuber yield of sequential treatments was similar to that of low-salinity control if the crop was irrigated with low-salinity water for 75% of its crop cycle. Regarding the accumulation of salts, plants accumulated sodium in roots, but not in shoots. Although chloride increased in all organs (mainly leaves and roots) with increasing salinity, the plant controlled chloride accumulation between 6.6 and 9.3 dS m-1. Results clearly proved that high chloride, not sodium, was responsible for the decreased accumulation of shoot and tuber biomass. Tubers were very low in starch (0.02% DW) and very high in inulin (50-60% DW). Salinity slightly increased inulin up to 6.6 dS m-1, while sucrose decreased sharply with salinity. Salinity did not affect the nutritional value of tubers. The cultivar Stampede is an early cultivar that completes its cycle in 4 months and produces (at 5.6 plants. m-2 and with water salinity of 6.6 dS m-1) 83 tons of tubers ha-1 (41.5 tons of inulin ha-1), while at low salinity the tuber production of Stampede can reach 92 tons ha-1 and 46 tons ha-1 of inulin. The crop is a rich source of inulin that can be used as a feedstock for biofuels, livestock feed, and as a non-caloric, prebiotic, soluble fiber for the food industry. The crop can adapt to different soils that are unsuitable for the production of staple agricultural crops, and can be cultivated with recycled or saline waters that are not suitable for human or animal consumption, or for the irrigation of agricultural crops. Jerusalem artichoke is a potential crop for growers facing saline soils and water in semiarid regions, but still willing to produce inulin for the biofuel and food market.