Plant Growth and Development Test - 6

The discovery of Kinetin is comparatively more recent. Its credit goes to Miller et al (1955) who were working in Prof. Skoog’s laboratory at the University of Wisconsin on the growth of tobacco pith callus in culture and wanted it to grow indefinitely.

Ethylene promotes female flowers in cucumbers thereby increasing the yield.

Ethylene is a simple gaseous hormone. It is synthesised in large amounts by tissues undergoing senescence and ripening fruits.

The most widely used compound as source of ethylene is ethephon. Ethephon in an aqueous solution is readily absorbed and transported within the plant and releases ethylene slowly.

There are more than 100 gibberellins reported from widely different organisms such as fungi and higher plants. They are denoted as GA1, GA2, GA3 and so on.

Phytochrome is a photoreceptor and a pigment that plants, and some bacteria and fungi, use to detect light. It is sensitive to light in the red and far-red region of the visible spectrum.

TIBA (2,3,5 Triidobenzoic acid) acts as antiauxin that inhibit root and shoot formation. TIBA is used as antiauxin in picking cotton bolls.

Flower Sex Conversions :

• Gibberellins (GA3) promote maleness
• Ethylene and auxins promote femaleness

Rotten fruit produce ethylene gas that hasten the ripening of unripe fruits. So, if a rotten fruit get mixed with unripe fruits the remaining unripe get ripen faster.

GA3 is a gibberellins that help in elongation of stem of the plant. If GA3 plant hormone is applied to the rice seedling the plant will show extra elongation of plant body.