Gibberellin

-

Gibberellin, one of the groups of hormones that influence the growth of plants. They are chemical substances that occur naturally in many plants and regulate various important functions, such as the elongation of flowering stems, the creation of proteins, and the germination of some plant seeds. Unlike auxins, which are plant hormones that form in the plant’s top shoots and flow downward to affect the growth of plant parts, gibberellins form in the seeds, young leaves, and plant roots before flowing upward into the stem.

Gibberellins were discovered in 1926 by Japanese scientists investigating foolish-seedling disease in rice. This disease caused rice shoots to grow extremely long without corresponding root growth. As a result, the seedlings did not flower and usually died before maturity. Foolish-seedling disease was traced to the fungus Gibberella fujikuroi, which produces substances now known as gibberellins. More than 50 different gibberellins have been isolated and identified; the most common is gibberellic acid. Scientists have developed chemical compounds, called growth substances, that are based on gibberellin hormones and can cause the elongation of flowering stems in certain plants during their growth period. These synthetic growth substances can also substitute for the natural hormone in plants where a genetic malfunction has blocked the production of gibberellins. Growth substances are also used to increase the yield and size of certain crops, such as seedless grapes.

Comments

Post a Comment

Popular posts from this blog

Plant: Cell Structure And Function

-
Image
Plant Cell Plant cells contain a variety of membrane-bound structures called organelles. These include a nucleus that carries genetic material; mitochondria that generate energy; ribosomes and rough endoplasmic reticulum that manufacture proteins; smooth endoplasmic reticulum that manufactures lipids used for making membranes and storing energy; and a thin lipid membrane that surrounds the cell. Plant cells also contain chloroplasts that capture energy from sunlight and a single fluid-filled vacuole that stores compounds and helps in plant growth. Plant cells are surrounded by a rigid cell wall that protects the cell and maintains its shape. The tremendous variety of plant species is, in part, a reflection of the many distinct cell types that make up individual plants. Fundamental similarities exist among all these cell types, however, and these similarities indicate the common origin and the interrelationships of the different plant species. Each individual plant cell is at
Read more

Insectivorous Plants

-
Image
Insectivorous Plants, also carnivorous plants, plants that gain some of their nutrition from animals, especially insects, captured by the plants themselves. Most occur in bogs where the soil is acid and poor in available nitrogen; capturing insects is one way of getting nitrogenous compounds without manufacturing them. At the same time, the green leaves of these plants manufacture carbohydrates. The trapping mechanism of insectivorous plants is relatively small. Therefore, prey is almost inevitably limited to small insects. Insectivorous plants are diverse and represent members of three orders of dicots : Nepenthales, Scrophulariales, and Rosales. A majority are in the Nepenthales, including the pitcher plant , sundews and the Venus's-flytrap, and East Indian pitcher plants. Others include the bladderworts, butterworts, and the Australian pitcher plant. Discussed below are the sundews and bladderworts. Certain species of fungus are known to be carnivorous as well. Venus’s-Flytrap
Read more

Parts of a flower

-
Image
All flowers share several basic features. Sepals, protective coverings that are closed over the bud before it blooms, are the outermost flower parts. One step inward lie the petals, which serve to attract pollinators using both coloration and scent-producing glands. Inside the petals are the flower's sexual organs, the stamens and pistil. Each stamen, the pollen producing part of the flower, includes an anther and a filament. At the center of the flower is the pistil, composed of a stigma, a style, and an ovary. Within the ovary is a small cavity that contains the ovule, an egg-shaped structure that, when fertilized, eventually becomes a seed. Flowers typically are composed of four parts, or whorls, arranged in concentric rings attached to the tip of the stem. From innermost to outermost, these whorls are the (1) pistil, (2) stamens, (3) petals, and (4) sepals. Pistil The innermost whorl, located in the center of the flower, is the female reproductive structure, or pistil. Often va
Read more