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Khudhair M.,CSIRO | Khudhair M.,Agricultural Research Directorate | Melloy P.,CSIRO | Melloy P.,University of Queensland | And 7 more authors.
Plant Pathology | Year: 2014

This study examines the CO2-mediated influence of plant resistance on crown rot dynamics under continuous cropping of partially resistant wheat line 249 and the susceptible cultivar Tamaroi. Disease incidence, severity, deoxynivalenol and Fusarium biomass were assessed after each cycle in microcosms established at ambient and 700 mg kg-1 CO2 using soil and stubble of these wheat lines from a field experiment with free to air CO2 enrichment. Monoconidial isolates from wheat stubble were collected initially, and after five cropping cycles, to compare the frequency and aggressiveness of Fusarium species in the two populations. Aggressiveness was measured using a high-throughput seedling bioassay. At elevated CO2, the higher initial incidence in Tamaroi increased with cropping cycles, but incidence in 249 remained unchanged. Incidence at ambient CO2 did not change for either line. Elevated CO2 induced partial resistance in Tamaroi, but not in 249. Increased Fusarium biomass in wheat tissue at elevated CO2 matched raised deoxynivalenol of the stem base in both lines. After five cycles of continuous wheat cropping, aggressiveness increased in pathogenic F. culmorum and F. pseudograminearum by 110%, but decreased in weakly pathogenic F. equiseti and F. oxysporum by 50%. CO2 and host resistance interactively influenced species frequency, and the highly aggressive F. pseudograminearum became dominant on Tamaroi irrespective of CO2 concentration, while its frequency declined on 249. This study shows that induced resistance at elevated CO2 will not reduce crown rot severity, or impede the selection and enrichment of Fusarium populations with increased aggressiveness. © 2013 British Society for Plant Pathology. Source


Ahmed S.M.,Agricultural Research Directorate | Kadhim A.H.,Agricultural Research Directorate
American-Eurasian Journal of Sustainable Agriculture | Year: 2014

The study was carried out in the greenhouse at AL-Twaitha Experimental Station/Baghdad, Agricultural Research Directorate, during December 2011 to February 2012 using Riviera cv potato. Treatments included effect of interaction between nutrient solution and foliar spray on potato plants grown hydroponically, Completely Randomized Design (CRD) was adapted. The results showed superiority of all fertilizer treatments under study comparing with the control treatment F0. Treatment F7 (Nutrient Solution + Agroleaf) significantly increased the number of stems, height of plant, leaf area and dry weight of shoots (4.00, 66.33 cm, 95.40Dcm2, 31.22 g respectively), in comparison with the control. Moreover this treatment showed significant increase in the percentage of N,P and K in the leaves (1.91, 0.99, 3.68%, respectively). compared with the control treatment which gave 0.13, 0.00, 1.07% respectively. However F5 treatment showed the highest percentage in N(1.06%) compared with the F0 treatment(0.07%.) in the tubers. © 2014 AENSI PUBLISHER All rights reserved. Source


Ahmed S.M.,Agricultural Research Directorate | Kadhim A.H.,Agricultural Research Directorate
American-Eurasian Journal of Sustainable Agriculture | Year: 2014

The study was carried out in the greenhouse at Al-Tuwaitha Experimental Station / Baghdad, Agricultural Research Directorate, during December 2011 to February 2012 using Riviera cv. potato. Treatments included effect of interaction between nutrient solution and foliar spray on potato plants grown hydroponically. Completely Randomized Design (CRD) was adapted. The results showed superiority of all fertilizer treatments under study comparing with the control treatment F0. Treatment F7 (Nutrient Solution + Agroleaf) significantly increased the number of stems, height of plant, leaf area and dry weight of shoots (4.00, 66.33 cm, 95.40Dcm2, 31.22 g respectively), in comparison with the control. Moreover this treatment showed significant increase in the percentage of N, P and K in the leaves (1.91, 0.99, 3.68%, respectively). compared with the control treatment which gave 0.13, 0.00, 1.07% respectively. However F5 treatment showed the highest percentage in N(1.06%) compared with the F0 treatment (0.07%.) in the tubers. © 2014 AENSI PUBLISHER All rights reserved. Source

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