Beendete Abschlussarbeiten

Das Mucigel ist ein polymerisches Gel, welches Polysaccharide und Lipide enthält. Es wird von der Wurzelspitze exudiert und kann große Mengen Wasser absorbieren. Dies hält die Rhizosphäre feucht, insbesondere unter trockenen Bedingungen. Mit einer steigenden Variabilität des Niederschlags und der Zahl an Wetterextremen (z.B. Dürrekönnte es eine wichtige Schlüsselrolle für unsere Feldfrüchte spielen, gerade um gleichbleibende Erträge, selbst unter ungünstigen Bedingungen, zu sichern.

Mein Projekt soll die Frage beantworten, ob und inwiefern sich die Sorte und die Wasserverfügbarkeit auf die Produktion von Mucigel und seine rheologischen Parameter auswirken. Dafür benutze ich zwei verschiedene Maissorten (B73 und Mo17), die je zwei verschiedenen Wassergehalten ausgesetzt sind. Die produzierten Mucigels werden auf ihreMenge, Viskosität und Oberflächenspannung getestet und miteinander verglichen. Außerdem werden wir das Verhalten der Mucigels im Boden mithilfe eines Neutronen-Radioskops näher betrachten. Dies erlaubt uns Messungen durchzuführen, ohne in den Boden einzugreifen.

Water availability is a primary limitation to crop production and depends on water input and soil texture, among others. A huge variety of sorghum landraces promises unexplored traits to overcome water stress, like high transpiration efficiency or early maturity.

 To test these, four sorghum landraces and one elite line were grown in four soil textures in a lysimetric facility in ICRISAT, India. Nitrogen fertilization was either added by mineralized or organic sources. The soil was dried down to 30 % usable field capacity. Weekly measured transpiration and data of biomass, plant development, yield and more will be analyzed and may reveal traits to overcome drought stress.

Limited water supply is one of the largest impediments to food production worldwide. Therefore, improving crop management of soil water depletion will be important to sustain the increasing food demand. The effect of belowground processes on transpiration and stomatal regulation remains controversial. Objective of this study was to understand the role of rhizosphere properties and processes, namely soil textural properties and root hairs, on transpiration, leaf water potential and stomata conductance with soil drying. We hypothesize that 1.) root hairs facilitate the water extraction from drying soils. This is expected to be reflected in the relation between transpiration rate and leaf water potential. Moreover, we expect 2.) different soil textures to affect root water uptake differently and therefore the relationship between leaf water potential and transpiration.

We compared maize (Zea mays L.) with (wild-type) and without (rth3-mutant) root hairs in three different soils (Alfisol, Vertisol and Sandy Soil) with different textural properties (loamy, clayey, sandy), respectively. Transpiration and leaf water potential were monitored, and stomata conductance calculated with decreasing soil water content and potential.

The hairless mutant declined transpiration at greater water contents or/ and exhibited lower transpiration rates in dry soils as compared to the wild-type. The relationship between leaf water potential and transpiration/ stomata conductance did not differ between genotypes, most likely because of prompt stomata closure. Moreover, plant transpiration responses to declining soil water content and – potential differed considerably between soils. Soil hydraulic characteristics and features like soil cracking in Vertisol as well as soil crust formation in Alfisol are believed to have influenced those relations. The relationship between transpiration and leaf water potential varied strongly between soils as well but stomata response to decreasing leaf water potential showed no direct sensitivity to soil texture. Therefore, we conclude that soil texture indirectly affected stomata by changing the soil-plant conductance.

In conclusion, this study provides experimental evidence of the strong link between stomata regulation and soil-root hydraulic properties. Further experiments will be needed for clarification and quantification.

Mucilage provides benefits for plant growth by maintaining the rhizosphere's water content during soil drying. The aerial root of maize (Zea mays L.) releases a significant amount mucilage to the rhizosphere. However, scarce information is available on quantitative and qualitative differences between the root exudation profile of the landrace and hybrid maize.

In this study, we find that mucilage production in the landrace is significantly different. The mucilage ability to store water potentially makes the landrace less vulnerable to drought. The variations of mucilage production in Maize cultivar would be significant for further analysis of crop adaptation to environmental stress.