Possible Consequences of Atmospheric Co2 Level Increment on Chemical Composition and Functional Properties of Maize (Zea Mays L.) and Wheat (Triticum Aestivum L.) Varieties in the Past Thirty Years Collected from Ambo District, Amaro Kebele, West Shoa Zone of Oromia, Ethiopia
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Date
2018-12-03
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Addis Ababa University
Abstract
Human activities contribute to climate change by causing changes in earth‟s atmosphere in the amounts of Green House Gases. Increment in atmospheric carbondioxide due to different anthropogenic activities are affecting yield of crops by increasing the rate of photosynthesis. This condition frequently alters chemical compositions of crops as a result of increase concentration of carbon in their tissues, with correspondingly reduced concentrations of other essential elements like protein and minerals. Based on this fact, this study was conducted in order to evaluate the possible consequences of increasing atmospheric carbondioxide level on chemical composition and functional properties of bread wheat (Triticum aestivum L.) and maize (Zea mays L.) from the past thirty years with five year intervals. The samples were collected from gene bank of Ethiopian biodiversity institute, which was collected from Ambo district, West Shoa Zone of Oromia. The official methods used were AOAC (2000, 2010, 2016), Elena (2012), AOAC (2001) and (Sathe et al., 1982a), (Adeleke et al., 2010), (Maninder et al., 2007) for Proximate composition, mineral analysis, total glucose and functional properties analysis respectively. Both samples with two different carbon fixation photosynthetic pathways show a significant (p<0.05) increment in moisture, utilizable carbohydrate and total glucose in the past three decades. Crude fat, crude protein contents shows a decrement (P<0.05) in Zea mays L. and Triticum aestivum L. (8.40-6.07%, 6.25% - 4.07%) and (3.70% –1.43% and 14.13–8.58%) respectively from 1987 to 2017 G.C. All minerals contents analyzed in Zea mays L. and Triticum aestivum L. flour sample have shown reduction at (P<0.05) with values of (22.05-15.97, 120.10-110.01, 2.02-1.98 and 1.99-1.87) and (31.5-29.09, 70.01-60.96, 1.49–0.95 and 2.20-1.03 mg/100gm) of Ca, Mg, Zn and Fe for both samples, respectively. The functional properties of the two samples were also investigated. The Water absorption capacity and bulk density for Zea mays L. and Triticum aestivum L. were recorded with significant increment at (P<0.05) and oil absorption capacity values on the other hand significantly reduced from (1.76-1.43 and 1.95-1.27 ml/g), respectively for each samples. Wet gluten content of Triticum aestivum L. also analyzed and show a decrement at (P<0.05) from (23.92% to 22.40%) in the past three decades. It can be concluded that direct effect of carbondioxide “fertilization” on the two key crops samples in this study has increase carbohydrate production and lower the levels of fat, protein, essential minerals and functional properties except water absorption and bulk density. Results in this study also show that three carbon photosynthetic pathway crop Triticum aestivum L. shows a notable reduction especially in protein content, Ca, Zn, Fe, wet gluten and increment in carbohydrate and total glucose content than that of four carbon photosynthetic pathway representing crop Zea mays L. within five years intervals in the past three decades which will be a large burden to nutritional perspective. And will be able to lead serious consequences of deficiencies and diseases for the future as this greenhouse gas in the atmosphere continues to increase.
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Green House Gases, Zea Mays L, Triticum Aestivum L, Carbondioxide, Carbondioxide “Fertilization”