true or false questions for plant physiology biology 425 the field capacity of s
ID: 166701 • Letter: T
Question
true or false questions for plant physiology biology 425
the field capacity of sand, silt and clay is the same (true or false?)
the amount of water held by sand, silt and clay at field capacity is the same (true or false?)
the permanent wilting percentage (pwp) for most plants is -5 MPa (true or false?)
all plants have the same PWP (true or false?)
sand holds water more tightly than clay (true or false?)
soil water potential is a function of osmotic potential and pressure (or matric potential which refers to the tension generated because of the adhesion of water to soil particles (true or false)?
the field capacity of sand, silt and clay is the same (true or false?)
the amount of water held by sand, silt and clay at field capacity is the same (true or false?)
the permanent wilting percentage (pwp) for most plants is -5 MPa (true or false?)
all plants have the same PWP (true or false?)
sand holds water more tightly than clay (true or false?)
soil water potential is a function of osmotic potential and pressure (or matric potential which refers to the tension generated because of the adhesion of water to soil particles (true or false)?
Explanation / Answer
Ans. 1) The field capacity of sand, silt, and clay is Different. Field capacity is referred to the situation when excess water has drained out due to gravitational force. At field capacity, the air and water contents of the soil are considered to be for crop growth. Therefore the above-given statement in question is False. The field capacity of Sand is =2.1-2.4 inches, Silt is = 3.6 -3.8 inches and Clay is = 4 - 4.4 inches.
Ans. 2) The amount of water held by sand, silt, and clay at field capacity is different. The water holding capacity of soil is called as water holding capacity. Therefore the above-given statement in question is False. Water holding capacity of sand is = 0.50 - 1.0 inches, silt is = 2 - 2.5 inches, and clay is =1.2 -1.5 inches. The water holding capacity of the plant shows that when the plant will become stressed.
Ans.3) The permanent wilting percentage (pwp) for most plants is not -5 MPa, The above - given statement is False. The permanent wilting point is the level of soil moisture at which a plant will not recover from wilting if placed in a humid chamber, and plant shows symptoms of water stress. The wilting percentage of most plants are about - 1.0 and -2.0 MPa, with a mean of 0.15 MPa.
Ans. 4) All plants have the same PWP. The above-given statement is False. Many species PWP at about -1.5 MPa. The value of PWP depends on the species as well as on the soil, different species have different PWP at the different value of soil.
Ans. 5) Sand holds water more tightly than clay is False. The fine particles of clay hold water more tightly than sand because clay generally retains more water holding capacity. This concept is based on porosity within sand and clay.
Ans. 6) Soil water potential is a function of osmotic potential and pressure and some other factors also. The statement given in the question is True. Soil water potential is then determined as potential energy per unit quantity of water, relative to the reference potential of zero. Soil water potential can be expressed by 3 different units
Potential per unit mass () : = potential/mass = gl (Nm/kg)
Potential per unit volume () : = potential/volume = rwVgl / V = rwgl (N/m2 , water pressure units)
Potential per unit weight (h) : h = potential/weight = mgl / mg = l (m, head unit) = equivalent height of water
Total soil water potential is T = p + z + s + a (N/m2 )
where p, z , s and a are pressure, gravitational, solute (osmotic) and air pressure potentials, respectively.
Water potential ((W) is measured by psychrometer. Pressure potential (p) is measured by Piezometers. Matric potential is measured by Tensiometers.
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