Original video: https://youtu.be/IhQpzz4mhuE
Delivered on: 17 April 2024
This video provides a foundational understanding of plant nutrition and water relations, essential for students of plant physiology, agriculture, and related fields. Nutrients is the components of food like carbohydrates, fats, proteins vitamins, minerals and water are called nutrients. Nutrition is the mode of taking food by an organism and its utilization in the body is called nutrition.
Modes of nutrition
1. Autotrophic
2. Heterotrophic
Synthesis of protein
The soil has some bacteria which convert nitrogen from the air into usable nitrogen in the soil. Farmers also add fertilisers containig nitrogen into the soil. Plants absorb this nitrogen from the soil along with water and other constituents to prepare proteins and fats.
There are two major ways to move molecules: A. Bulk (or Mass) Flow- is the mass movement of molecules in response to a pressure gradient. The molecules move from high to low pressure, following a pressure gradient. B. Diffusion - the net, randomly movement of individual molecules from one area to another. The molecules move from high to low concentration, following a concentration gradient. Another way of stating this is that the molecules move from an area of high free energy (higher concentration) to one of low free energy (lower concentration). The net movement stops when a dynamic equilibrium is achieved. Osmosis is a specialized case of diffusion; it represents the diffusion of a solvent (typically water) across a membrane.
Water potential is a measure of the energy state of water. This is a particularly important concept in plant physiology because it determines the direction and movement of water. Water potentials in intact plant tissue are usually negative (because of the large quantities of dissolved solutes in cells). Water always moves from an area of higher water potential to an area of lower water potential. Water potential is affected by two factors: pressure and the amount of solute.
Equation for water potential (must account for the factors that influence the diffusion of
water): Ψw = Ψp + Ψs + Ψg
Where, Ψw = water potential
Ψp = pressure potential
Ψs = solute or osmotic potential
Ψg = gravity potential
Solute (or osmotic) potential (Ψs) is the contribution due to dissolved solutes. Pure water at atmospheric pressure has a solute potential of zero. As solute is added, the value for solute potential becomes more negative. This causes water potential to decrease also. In sum, as solute is added, the water potential of a solution drops, and water will tend to move into the solution.
The solute potential of a solution can be calculated with the Van’t Hoff equation:
Ψs = - miRT
Where, m = molality (moles/1000 g)
i = ionization constant (often 1.0)
R = gas constant (0.0831 liter bar/mole K)
T = Temperature in degrees Kelvin (273 + °C of solution)
Pressure (or Pressure Potential; Ψp)- In a plant cell, pressure exerted by the rigid cell wall that limits the further water uptake. It is usually positive, although may be negative (tension) as in the xylem. Pressure can be measured with an osmometer. Matric potential is the contribution to water potential due to the force of attraction of water for colloidal, charged surfaces. It is negative because it reduces the ability of water to move. In large volumes of water, it is very small and usually ignored. However, it can be very important in the soil, especially when referring to the root/soil interface. Gravity (Ψg) is contributions due to gravity, which is usually ignored unless referring to the tops of tall trees.
Keywords: Crop Physiology, Plant Nutrition, Mineral Nutrition, Macronutrients, Micronutrients, Nutrient Absorption, Diffusion, Mass Flow, Active Transport, Water Potential, Solute Potential, Pressure Potential, Osmosis, Plant Growth, Plant Development, Plant Science, Agriculture
Location:
Faculty of Agriculture, Universiti Putra Malaysia
Fakulti Pertanian, Universiti Putra Malaysia, 43000 Seri Kembangan, Selangor
XPMM+9J Seri Kembangan, Selangor
2.9845517506267742, 101.73803356324866
Attribution 4.0 International — CC BY 4.0 - Creative Commons
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