Horticulture Techniques for Profit

PGRs and Economic Implications

• PGRs (Plant Growth Regulators) are endogenous and exogenous substances that affect plant growth and development in many ways, having direct economic implications.

PGRs as a New Source of Productivity Growth

• Rising global demand for food production and the need for improvement in agricultural productivity have led to the use of chemicals to improve crop plant growth and development.
• The use of PGRs to improve crop growth and development dates back to the 1930s with the discovery of auxins.

Categories of Economic Benefit

• PGRs have various economic benefits, including:
  • Uses to increase output:
• Increasing yield
• Improving quality
• Increasing value
• Extending season and continuity of supply
  • Cost-saving uses:
• Direct labor replacement
• Facilitating mechanization
• Simplifying plant breeding
• Extending season and continuity of supply

Uses to Increase Output

• Increasing yield:
• Chlormequat chloride to shorten and stiffen wheat straw, allowing increased use of nitrogen fertilizers
• GA (Gibberellins) to increase fruit set of mandarin, clementines, and tangerines, with a benefit/cost ratio of 9:1
• GA to overcome losses of apple yield due to frost damage
• GA to increase berry size of seedless grapes, with a benefit/cost ratio of 40:1
• GA to overcome low-temperature constraints to sugarcane growth
• Ethapon to stimulate latex flow in rubber
• Glyphosine to ripen sugarcane, resulting in a 10-15% increase in sucrose
• Improving quality:
• GA + mechanical thinning to increase berry size of seedless grapes
• Ethylene to de-green citrus fruit
• Daminozide or chlorphonium chloride to dwarf pot-plants, making them more acceptable to the consumer market
• Gibberellins to delay ripening and improve storage life of bananas
• Increasing value:
• GA to advance or retard maturity of artichoke to capture higher prices
• GA to retard ripening of grapefruit to spread harvesting and capture higher prices
• Extending season and increasing continuity of supply:
• Maleic hydrazide and other sprouting inhibitors to extend storage of bulbs and root crops
• GA to force rhubarb for early production

Cost-Saving Uses

• Direct labor replacement:
• Maleic hydrazide and fatty alcohol contact bud killers to control growth of suckers in tobacco
• NAA (Naphthaleneacetic acid) to thin overset fruit
• Dikegulac-sodium to control growth of hedges
• Facilitating mechanization:
• Fruit looseners (e.g., Ethapon) to aid synchronized ripening and loosening of fruit for mechanical harvesting
• Retardants (e.g., daminozide) to reduce length of peanut runners and facilitate harvesting
• Defoliants to remove excessive vegetation on crops
• Simplifying plant breeding:
• Sex change in Cucurbits: a mixture of Gibberellins A4 and A7 to increase staminate flowers
• Extending season and increasing continuity of supply:
• Maleic hydrazide to extend storage of bulbs and root crops

Conclusion

• The success of PGR use depends on:
  • Clear understanding of the need of agriculture
  • Scope for growth modifications
  • Various plant physiological processes

Quiz on various techniques used to increase value in horticulture, including advancing or retarding plant maturity, extending seasonal supply, and cost-saving methods.