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AGRICULTURAL UNIVERSITY OF ATHENS DEPARTMENT OF CROP SCIENCE LABORATORY OF AGRONOMY. Effect of deficit irrigation practice on the weed flora in a corn crop V. E. Kotoulas, K. Karfi, I. S. Travlos, D. Voloudakis, G. Economou and A. Karamanos. HUESCA 4-8 SEPTEMBER 2011.
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AGRICULTURAL UNIVERSITY OF ATHENS DEPARTMENT OF CROP SCIENCE LABORATORY OF AGRONOMY Effect of deficit irrigation practice on the weed flora in a corn crop V. E. Kotoulas, K. Karfi, I. S. Travlos, D. Voloudakis, G. Economou and A. Karamanos HUESCA 4-8 SEPTEMBER 2011
At present and more so in the future, irrigated agriculture will take place under water scarcity • Irrigation management will shift from emphasizing production per unit area towards maximizing the production per unit of water consumed, the water productivity. The state of the art
To cope with scarce supplies, deficit irrigation, defined as the application of water below full crop-water requirements (evapotranspiration), is an important tool to achieve the goal of reducing irrigation water use. • 2 ways: a. During whole growing period b. only during “biological windows” • The level of deficit irrigation is calculated according to plant water demands based on Penman-Monteith equation. The state of the art
Many researches were conducted on the effects of deficit irrigation on several crops or trees. • However, it is not still clear the way that deficit irrigation practices affects the growth of the weeds. The state of the art
The way that water shortage affects the weed development in relation to corn crop yield. Sub objective • The physiological effects of water shortage on the weed flora. The objective
To investigate if the deficit irrigation can be used as an effective mean for weed management. The scope of the study
Crop: ZeamaysL. • Weeds: Amaranthusretroflexus, Solanumeleagnifolium, Tribulusterrestris • No application of herbicides • Irrigation method: Drip irrigation (except the first 2 irrigations that were applied with sprinklers) • Beginning of DI treatments: When the corn developed 5-6 leaves Materials and methods
Irrigation dose: Based on Penman – Monteith equation we calculated ET0 and we used it to calculate Etc (ETc= Kc*ET0). • Data we used in order to calculate Evapotranspiration (ET0): Air Temperature, Relative Humidity, Wind speed and Solar radiation. Treatments: • Full Irrigation (A): 80%*Etc • Deficit Irrigation 1 (B): 65%* Etc • Deficit Irrigation2 (C): 50%* Etc Materials and methods
Measurements and observations: • Weed density (plants/m2) • Dry weight • Stomatal resistance • Leaf water potential • Corn yield Materials and methods
ResultsClimatic conditionsMeteorological data Fig. 1. Air temperature during the experimental period Fig. 2. Relative humidity during the experimental period Fig. 3. Solar radiation during the experimental period Fig. 4. Wind speed during the experimental period
Results ET0 Evapotranspiration (mm) ETc Precipitation during the experimental period DAS Reference (ET0)and Crop (Etc) Evapotranspiration
Results Weed density of the 3 weed species 110 DAS
Results Dry weight of the 3 weed species and the corn 110 DAS
Results Fig.9. Leaf water potential of the 3 weed species and the corn 110 DAS
Results Fig.10. Stomatal resistance of the 3 weed species and the corn 110 DAS
Results Fig.11. Corn yield
As far as the density of weeds concerns, no significant differences were observed among the water treatments The highest dry weight values were observed for the second level of deficit irrigation for S. eleagnifolium and T. terrestris, but not for A. retroflexus. On the contrary, corn showed the highest value of dry weight when irrigated full Discussion
Physiological point of view • Leaf water potential values were higher in full irrigation treatment and lower in the second level of deficit irrigation both for weeds and corn. • Stomatal resistance values were higher in C treatment and lower in A and B. • Especially for Solanum and Tribulus did not differ between A and B treatments. Discussion
Corn as a C4 plant reacts faster and better than the other species (C3 plants), making corn more competitive against the weeds in full irrigation conditions. • On the other hand, when deficit irrigation is applied, weeds (Solanum and Tribulus) are presented more competitive against corn. Discussion
S. eleagnifoliumat high risk as an invasive weed to Mediterranean type regions have was affected from water shortage. • A. retroflexus: DI could be an effective method for the control of these weeds, especially in other crops (cotton) that respond better than corn in water shortage. Conclusions
The expected climate change will cause an expantion of the xerothermic zone and this will favour the occurance of such xerophytic weeds. Conclusions