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Gewählte Doctoral Thesis:

Amir Raza (2011): Water relations of lucerne (Medicago sativa L.) under organic farming conditions.
Doctoral Thesis - Institut für Ökologischer Landbau (IFÖL), BOKU-Universität für Bodenkultur, pp 244. UB BOKU obvsg FullText

Data Source: ZID Abstracts
Experimental and modeling studies were carried out during 2007-2008 to compare lucerne varieties and utilization systems for yield and water use. Simulation model CropSyst was used. Non-significant differences were observed among varieties for shoot dry matter yield and water use efficiency. Relatively higher yield and water use efficiency were observed under irrigated conditions than under rain-fed conditions. On the overall basis, Sitel was found superior variety in terms of its better yield and water use efficiency under both irrigated and rain-fed conditions. Differences of a mulching system vs. no mulch were found non-significant as determined at the time of second harvest in each year while differences among years were found significant (P < 0.01) for shoot dry matter yield, biological nitrogen fixation and water use efficiency. Higher values of yield and water use efficiency in 2008 than in 2007 can be due to higher rainfall in 2008. Based on results from modeling, we found that CropSyst has the potential to simulate crop biomass and soil water content under varying levels of water availability. Scenario analysis by varying plant traits such as maximum rooting depth, specific leaf area and stem/leaf partitioning coefficient helped to hypothesize an ideotype for water limited conditions at Raasdorf. Irrigation requirements of rain-fed lucerne were assessed by varying amount and interval of irrigation under high and low rainfall scenarios. The effect of supplemental irrigation was more pronounced in low rainfall years and irrigation with 40 mm of water at 20 days interval during the period from June-September can help to achieve about 6 tones ha-1 of additional above ground biomass. Modeling the effect of mulch using CropSyst indicated that mulching tends to increase soil water content mainly in upper 10 cm soil layer but this effect is not translated into biomass accumulation probably due to the smaller amounts of water conserved as well as due to the smaller duration of field experiments.

Betreuer: Friedel Jürgen Kurt
1. Berater: Gollner Gabriele
2. Berater: Bodner Gernot

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