Vestimentiferan tubeworms have no mouth or gut, and the majority of their nutritional requirements are provided by endosymbiotic bacteria that utilize hydrogen sulfide oxidation to fix CO(2) into organic molecules. It has been assumed that all vestimentiferans obtain the sulfide, O(2) and CO(2) needed by the bacteria across the plume (gill) surface, but some live in locations where very little ...

a growth chamber study was carried out to evaluate the allelopahtic effects of shoot and root water extract of hoary cress (cardaria draba) on seed germination and seedling characteristic of sorghum (sorghum bicolor). the study was conducted based on completely randomized design with four replications in research laboratory of faculty of agriculture, university of birjand in 2008. treatments we...

abstract different definitions have been proposed for soil quality. various soil properties have been suggetsted as soil quality indices by researchers. this research was conducted to study the relationship between slope of retention curve at its inflection point (s index) and other soil physical quality indices, because the reserches between s index and soil physical properties are little. thi...

[1] Correct representations of root functioning, such as root water uptake and hydraulic redistribution, are critically important for modeling the responses of vegetation to droughts and seasonal changes in soil moisture content. However, these processes are poorly represented in global land surface models. In this study, we incorporated two root functions: a root water uptake function which as...

Plants of Rumex thyrsiflorus Fingerh., R. crispus L. and R. muritimus L., which are zoned along a gradient of elevation in a river foreland ecosystem, and differ in their flood-tolerance, were subjected to different Hooding levels. Under conditions of soil flooding, the growth rates of the flood-tolerant R. crispus and R. muritimus were as high as under drained conditions, but that of the flood...

Plants of Rumex thyrsiflorus Fingerh., R. crispus L. and R. muritimus L., which are zoned along a gradient of elevation in a river foreland ecosystem, and differ in their flood-tolerance, were subjected to different Hooding levels. Under conditions of soil flooding, the growth rates of the flood-tolerant R. crispus and R. muritimus were as high as under drained conditions, but that of the flood...

certain conditions. However, because root-system development is not considered in these water-extraction A two-dimensional model that combines root-system development models, the root length per unit soil volume should be and water extraction by roots is proposed to simulate the dynamic interaction between root growth and soil-water flow. Both of hydrotrogiven a priori as a function of soil dep...

Root conductance increases under high nitrate conditions. This plasticity might increase water and nutrient transport between parallel xylem pathways, but restrictions to lateral flow – called sectoriality – are expected to limit this crossover. We simulated the effects of a high nitrate patch on root conductance, water uptake and inter-sector water transport, then empirically tested whether a ...

BACKGROUND AND AIMS Soil phosphorus (P) solubility declines sharply when a flooded soil drains, and an important component of rice (Oryza sativa) adaptation to rainfed lowland environments is the ability to absorb and utilize P under such conditions. The aim of this study was to test the hypothesis that rice cultivars differ in their P responses between water regimes because P uptake mechanisms...