Crop Ecophys Gibberellins (GAs)

In what organisms do GAs occur

higher plants as well as some species of bacteria and fungi

Presently how many fully characterized GAs are there?

136

In1950’s, Radley found that application of a pea seedling GA extract restored — in the — pea plants

height, dwarf

Where are GAs produced

in meristem of apical buds and roots, in young developing leaves, stems, roots, and seeds

GAs control many aspects of plant development

-Stimulate stem elongation and leaf growth

-Promote seed germination and bud outgrowth

-Affect root growth and differentiation

-Stimulate flowering and development of fruit

-Promote seed growth and developemnt

4 groups of GA biosynthesis inhibitors

—- and — are primarily used as anti-lodging agents in cereal production

Chlormequat chloride, mepiquant chloride

Structural mimics of — are used for stem stabilization (reduction) in cereal crops, rice, and oilseed rape, growth control in turf grasses, and reduction of vegetative growth in fruit trees

2-oxoglutaric acid

Which hormone used in the Malting Barley Process

GAs

GA application at bloom for grapes

-Decrease in pollen viability and ovule fertility

-Decrease in fruit set and # of berries/cluster

-Increase in weight and length of remaining fruits

GA application at fruit set of grapes

Further increase in berry size

Which hormone used to increase internode growth and sugarcane yeild

GAs

Which hormone used to induce cone production in conifers?

GAs

Which hormone used to control flower sex expression in cucumbers and squash and how?

GAs promote the formation of male flowers so both male and female flowers present for hybrid seed production.

Which hormone used to stimulate bolting and seed stalk formation in many biennial vegetables facilitating hybrid seed production and vegetable variety improvement?

GAs