● The basic needs of all `color{violet}"living organisms"` are essentially the same.

● They require `color{violet}"macromolecules"`, such as carbohydrates, proteins and fats, and `color{violet}"water and minerals"` for their growth and development.

● In `color{Brown}"1860, Julius von Sachs"`, a prominent `color{violet}"German botanist"`, demonstrated, for the first time, that plants could be `color{violet}"grown to maturity"` in a `color{Brown}"defined nutrient solution"` in complete absence of soil.

● This technique of `color{violet}"growing plants"` in a `color{violet}"nutrient solution"` is known as `color{Brown}"hydroponics"`.

● Since then, a number of `color{violet}"improvised methods"` have been employed to `color{violet}"try and determine"` the mineral nutrients essential for plants.

● The `color{violet}"essence"` of all these methods involves the `color{violet}"culture of plants"` in a `color{violet}"soil-free, defined"` mineral solution.

● These methods require `color{violet}"purified water"` and `color{violet}"mineral nutrient salts"`.

● After a `color{violet}"series of experiments"` in which the `color{violet}"roots of the plants"` were immersed in nutrient solutions and wherein an `color{violet}"element was added / removed"` or given in varied concentration, a `color{violet}"mineral solution"` suitable for the plant growth was obtained.

● By this method, `color{Brown}"essential elements"` were identified and their `color{violet}"deficiency symptoms"` discovered.

● `color{violet}"Hydroponics"` has been successfully employed as a technique for the `color{violet}"commercial production"` of vegetables such as `color{Brown}"tomato"`, `color{Brown}"seedless cucumber"` and `color{Brown}"lettuce"`.

● It must be emphasised that the `color{violet}"nutrient solutions"` must be `color{Brown}"adequately aerated"` to obtain the `color{violet}"optimum growth"`.

● Most of the `color{violet}"minerals present in soil"` can enter plants through `color{violet}"roots"`.

● In fact, more than `color{Brown}"sixty elements"` of the `color{violet}"105 "`discovered so far are found in `color{violet}"different plants"`.

● Some plant species accumulate `color{violet}"selenium"`, some others `color{violet}"gold"`, while some plants growing `color{violet}"near nuclear test sites"` take up `color{violet}"radioactive strontium"`.

● There are `color{violet}"techniques"` that are able to detect the minerals even at a `color{violet}"very low concentration"` (`10_-8 g/ mL`).

● The question is, whether all the `color{violet}"diverse mineral elements"` present in a plant, for example, gold and selenium as mentioned above, are `color{violet}"really necessary for plants"`?