Date of Award

6-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Agricultural Education

First Advisor

Dr. Elke Neumann

Second Advisor

Dr. Mustafa Fadl

Third Advisor

Dr. Mohamed Salman Al Hammadi

Abstract

The UAE and its neighboring countries are encountering scarcity of water resources and soil degradation due to salinization. The current over-exploitation of aquifers by the agricultural sector is a major concern for the government. Open field production of forage as a feed for camels, cows and small ruminants requires particularly high amounts of irrigation water. Greenhouse production of fodder might save water, but would require a suitable growth substrate that is readily available in the UAE, and ideally constitutes a palatable fodder itself. The objective of this study was to evaluate the suitability of ground D.pits and G.pods as growth substrates for greenhouse cultivation of barley (Hordeum vulgare) and maize (Zea mays L.) as fodder. A series of three experiments was conducted throughout 2011 by utilizing the laboratory and greenhouses of the Al-Foah Experimental Farm of the UAE University, AI-Ain, UAE. In a first experimental approach, freshly ground D.pits and G.pods were compared with the standard growth medium cocopeat (C.peat) for their ability to support growth of the target plants. This experiment revealed that both substrates severely impaired plant growth, and were not suitable as a growth medium. High concentrations of phenolic compounds commonly found in D.pits and G.pods might be a reason for this. A second experimental approach tested whether compounds that impaired plant growth on the fresh substrate could be removed by a hot water extraction. This experiment confirmed that at least some of the inhibitory compounds are soluble in hot water. However, even two cycles of hot water extraction were not sufficient to render the D.pits or G.pods suitable growth media for barley. A third experimental approach tested whether microbial decomposition could improve the suitability of G.pods as growth substrate for barley. For this purpose, the Ground G.pods were mixed with water, and then allowed to ferment either under anaerobic or aerobic conditions. When the material was subject to a combination of anaerobic and aerobic fermentation, it indeed lost its inhibitory compounds, and supported plant growth as good as C.peat Anaerobic fermentation alone was not sufficient to remove inhibitory compounds. Whether the ground G.pods would still be accepted as a fodder by farm animals after fermentation, still needs to be tested by future experiments. All in all our results suggest that D.pits and G.pods could be used as growth substrates for greenhouse cultivation of fodder plants, under the prerequisite that future research identifies and further refines methods for extraction of plant growth inhibitory compounds.

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