Prevent Frost Damage to Plants: Tips & Solutions

[pivoxa15]

Homework Statement

Plants when exposed to frost can be badly damaged as the frost melts. Why? Explain how the damage can be minimised by spraying the plants with water.

Homework Equations

none

The Attempt at a Solution

It could be due to frost expand when in cells (i.e. from liquid water to ice, the volume of ice is larger than water) hence when turned it melts, the plant cells are ruptured. So spray water will fill the ruptured cells and so they look fresher or not saggy.

Or it could be as frost melts, heat energy is absorbed so the surrounding air becomes cooler. The water sprayed on plants contain heat already so heat is sucked out of the added water instead of the plants themselves.

Which is correct? Any other solutions?

 

[Astronuc]

At room temperature, liquid water becomes denser with lowering temperature, just like other substances. But at 4 °C, just above freezing, water reaches its maximum density, and as water cools further toward its freezing point, the liquid water, under standard conditions, expands to become less dense. The physical reason for this is related to the crystal structure of ordinary ice, known as hexagonal ice Ih. Water, gallium, bismuth, acetic acid, antimony and silicon are some of the few materials which expand when they freeze; most other materials contract.

http://en.wikipedia.org/wiki/Water_(molecule)#Density_of_water_and_ice

http://www.elmhurst.edu/~chm/vchembook/122Adensityice.html

http://www.thermexcel.com/english/tables/eau_atm.htm - see density from 0 to 5°C.

 

[pivoxa15]

So my first answer is correct? The added liquid will fill the expanded cell walls so that the sight of damage is not made apparent.