Quantification of water uptake of hyphae contributing to barley subjected to drought conditions
Year: 2005
Type: dissertation
Abstract: To investigate the quantification of water uptake by extraradical hyphae and effect of root mycorrhization on water relations of host plants several experiments were carried out in this study. We evaluated the effects of colonization of barley (Hordeum vulgaris L. var. Scarlett) roots with two VAM fungi (Glomus intraradices and Glomus mosseae) on growth, yield components, leaf water relations and acquisition of nutrients under simulated drought or well-watered conditions in a greenhouse. We observed mild effects of the two mycorrhizal fungi on leaf water relation between VAM and non-VAM drought stressed plants but no specific effects on yield parameters or plant nutrients uptake. However, that drought conditions surprisingly increased root colonization by VAM. Though under drought condition, only G. intraradices changed the leaf area of plants slightly but statistically significant. We also noted some differences between G. intraradices and G. mosseae in their effect on nutrient uptake by barley under the same growth conditions. In the split-root-hyphae system experiments we subjected barley plants to simulated drought and studied the effects of symbiosis with vesicular arbuscular mycorrhizal fungi (Glomus intraradices) on water uptake and elongation of plant leaves. Ninety days after sowing, the initial gravimetric soil water content was reduced by about 2-4 % in the hyphae compartments of drought stressed plants with vesicular arbuscular mycorrhizal fungi (VAM plants) as compared to that in the plants without vesicular arbuscular mycorrhizal fungi (non-VAM plants). In this study, leaf water potential was lower in VAM plants, relative leaf water content and leaf turgor pressure were all higher in VAM plants than in the non-VAM plants, but at the end of the drying cycles leaf 5 on the mainstem of drought stressed VAM plants was 33% longer than in the non-VAM plants. We suggest, however, that the improved leaf water relations, longer leaf, and faster leaf elongation rate in the drought stressed VAM plants compared with the non-VAM plants, might have been due to the impact of VAM on plants which were independent on the higher contribution of VAM hyphae to water uptake by drought stressed VAM plants. Effect of VAM on the transport of water to barley roots from a physically separate soil compartment (hyphae compartments) was measured by means of capacitance sensors in the last experiment. Results indicated a decrease in soil water content in the hyphae compartments of plants colonized by vesicular arbuscular mycorrhize (VAM) when compared to the corresponding values in the compartment of control treatment (non-VAM plants). This was taken as evidence for the uptake of water by the extraradical hyphae and its transfer to the host plants in the adjacent, but physically unattached, plant compartment (PC). Measurements showed that under drought condition, VAM hyphae transported 5-7% of the soil water from the hyphae compartments to the plant compartment as compared with non-VAM plants. The data also showed indications for a reverse mass transport of water from the plant compartment (when plants were periodically watered) to the hyphae compartment by the hyphae strands connecting the two compartments.
Author: Mohammad Ali Khalvati
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2747182055