Question

assignment on hydrotropesm

Answer 1

The mechanism of root hydrotropism has been a mystery for many years, due to the complexity of the interactions between the external environment and plants themselves. To gain an engineering perspective, the time-dependent hydrotropism of a single root has been modeled, initially using a two-dimensional model. Based on the water and nutrient distribution in rhizosphere as computed with the conservation equations, together with a basic reaction-kinetics-type growth model and an intuitive root bending model, it has been found that the root already possesses the property of hydrotropism. For the first time, hydrotropism could be tracked by a process engineering model, which is a new idea based on chemical engineering concept, suggesting an alternative mechanism of hydrotropism. The effects of different initial root widths, lengths, and other growth/transport coefficients on root hydrotropism have then been explored.

Answer 2

Hydrotropism is a plant's growth response in which the direction of growth is determined by a stimulus or gradient in water concentration. A common example is a plant root growing in humid air bending toward a higher relative humidity level.

Hydrotropism

This is of biological significance as it helps to increase efficiency of the plant in its ecosystem.

The process of hydrotropism is started by the root cap sensing water and sending a signal to the elongating part of the root. Hydrotropism is difficult to observe in underground roots, since the roots are not readily observable, and root gravitropism is usually more influential than root hydrotropism.[2] Water readily moves in soil and soil water content is constantly changing so any gradients in soil moisture are not stable.

Root hydrotropism research has mainly been a laboratory phenomenon for roots grown in humid air rather than soil. Its ecological significance in soil-grown roots is unclear because so little hydrotropism research has examined soil-grown roots. Recent identification of a mutant plant that lacks a hydrotropic response may help to elucidate its role in nature.[3] Hydrotropism may have importance for plants grown in space, where it may allow roots to orient themselves in a microgravity environment.[4]

This behavior is thought to have been developed millions of years ago when plants began their journey onto dry land.[5] While this migration led to much easier consumption of CO2, it greatly reduced the amount of water readily available to the plants. Thus, strong evolutionary pressure was put on the ability to find more water.

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