What makes plants grow? Several people have puzzled over this question. There is no one single answer to this. Several factors contribute: Tropisms, environment, hormones, biological clocks, and even humans. We are trying to determine the effects of music on plants. It takes all these combined to have a plant that actually grows and a plant that is healthy and happy in its habitat.
Hormones contribute greatly to the growth of plants. Hormones such as auxins, gibberellins, cytokinins, and inhibitors make plants start growing through stimulation, have protein synthesis, maintain growth, and also inhibit plant growth, respectively. Hormones, very simply, control the plantís instincts to grow.
Auxins accumulate in certain parts of the plant, for example the
stems grow toward the light. Auxins also make roots grow and make the veins in leaves grow. Tropisms, which are discussed later, in conjunction with auxins, make the plant grow in the proper direction.
Gibberellins are the leaves and roots that form in the baby plant seed. Gibberellins are also responsible for protein synthesis, which is the building of protein for basic life purposes. Gibberellins are used commercially to promote flowering and fruit development because of their growth stimulation.
Cytokinins are a group of natural plant chemicals found in endosperms, the nutritive tissue of embryonic seeds, and in the development of fruit. The cytokinin zeatin, in conjunction with auxins, stimulates cell division, particularly for shoot growth. Cytokinins also maintain cell growth, differentiation, and division.
Inhibitors are hormones that inhibit plant growth. Some inhibitors make the plant leaves fall off in the Autumn. Other inhibitors prevent the formation of buds in cold seasons. Ethylene makes fruit ripen which inhibits certain plants from maturing fully.
The Environment
All plants need a fitting place to call home. This place is called its environment. Everyone knows that plants need suitable climate, water, and sunlight for photosynthesis in their environment.
In certain plants, shade is needed for proper growth but some light
is still needed. The length of the periods of light a plant receives also affects its growth and flourishment. Photosynthesis occurs using the suns energy to create the plants own energy. Long-day plants blossom only during the long periods of sunlight. Short-day plants bloom when the dark period is long. There are other types called day-neutral which are not affected by the duration of light.
All plants need different amounts of water. Some plants need lots of water, like the and when they grow in the wild they grow in the tropical regions of the Earth where there is an abundance of rain water. Plants like the Cacti grow only in the desert regions of the Earth where there is little rain. The pathos ivy requires only a medium amount of water.
The other factor is the climate. Again, the cacti needs a warm climate like the desert. The evergreen plant like firs normally grow in the tiaga regions of the Earth. The pathos ivy grows in temperate regions of the Earth. Climate is an important factor when determining plant growth.
In botany the orientation or directed movement of plants in response to an external stimulus is called a tropism. Tropisms are classified according to the nature of the stimulus: a response to light is called phototropism; a response to gravity is called a gravitropism which used to be called a geotropism.
A phototropism is a response to light so there must be a pigment
present to absorb the light. The effective light is normally from the blue region of the spectrum. The significance of phototropism to the plant is to assist in making the plant grow toward the light that it requires.
Growth movements in response to gravity are called gravitropism. Roots are gravitropic, growing in the direction of the Earth\'s gravitational field. Primary roots are more positively gravitropic than secondary roots. Shoots are negatively gravitropic, growing away from the gravitational field.
Gravitropisms are caused by different auxin concentrations, with more auxins collecting on the lower side of the shoots or roots. How higher concentrations on the lower sides of both shoots and roots produce opposite effects are not clear.
Biological Clocks
Biological clocks, physiological systems that enables organisms to live in harmony with the rhythms of nature, trigger certain cells and hormones that are crucial in the growth and development if plants. These clocks aren\'t perfect though they are necessary