Biological World

 

  Plant Nutrition.                               Plants use inorganic minerals for nutrition, whether grown in the field or in a container. Complex interactions involving weathering of rock minerals, decaying organic matter, animals and microbes take place to form inorganic minerals in soil. Roots absorb mineral nutrients as ions in soil water. Many factors influence nutrient uptake for plants. Ions can be readily available to roots or could be tied up by other elements or the soil itself. Soil too high in pH (alkaline) or too low in pH (acidic) makes many minerals unavailable to plants.There are 20 mineral elements essential for plant growth.The rest of the elements are required in trace amounts(micronutrients).Studies have also shown that a number of other mineral elements are beneficial to the growth of plants and are required for some pla...

  Osmotic potential        Osmotic pressure of a solution may also be defined as the excess hydrostatic pressure which must be applied to it order to make it water potential equal to that of pure water. Since in a literal sense, no actual pressure is developed, unless the solution is placed in an osmometer, it is preferable to use the term osmotic potential instead of osmotic pressure. Osmotic potential being equal in magnitude but opposite in sign to osmotic pressure (π). Thus π = ᴪ s (osmotic potential).        Since the osmotic potential of dilute solution of sucrose is directly proportional to the concentration of solute and the absolute temperature. On the basis of Vant Hoff’s equation, op can therefore be written as-        ᴪ s (o.p.) = -n/v RT        where n is the   number of mol of solute in solution of volume V, R is the gas constant and T ...

  Q.  What is aeroponic system of plant culture? Diagrammatically represent the system.     2+6                                                       Aeroponics : Aeroponics is defined by the International Society for Soilless Culture as “a system where roots are maintained in an environment saturated with fine drops (a mist or aerosol) of nutrient solution” . In other words, instead of planting crops directly into the soil or media or growing them in a nutrient rich liquid solution, aeroponics relies upon applying a fine mist of nutrients and water directly onto the roots themselves. The plant is typically suspended or supported in some manner and the roots allowed to grow freely in the air inside a closed chamber without con...