THE EFFECT OF PLANT GROWTH REGULATORS ON SOME VEGETABLE CROPS IN GHANA - A REVIEW OF RECENT RESEARCH

S. Sinnadurai
Growth in plants is controlled by many factors, including plant hormones. Considerable work in this field has been done in recent years and, due to the varied effects that hormones exert on plant growth, horticulturists prefer to regard chemicals which have growth promoting or growth retarding effects as growth regulators.

Plant growth regulators are widely used by horticulturists in Europe and the U.S.A., but their use in Africa is restricted mainly to the vegetative propagation of plants. Research investigations on the use of a few of these chemicals such as maleic hydrazide, chlormequat (cycocel) and gibberellic acid on some vegetables have given interesting results.

  1. Maleic hydrazide: The application of this chemical on the 'Bawku' cultivar of onion, which flowers readily, produced a significant decrease in flowering. Maximum effect was obtained with 300 ppm without affecting bulb size and quality. With applications higher than 300 ppm bulbs were soft and light in weight. The control of bolting in the 'Bawku' onion enables farmers to obtain higher yields of good quality onions.
  2. Chlormequat (Cycocel): This chemical has given good results during the last three years on the following crops:
    1. Tomato (Lycopersicon esculentum). Chlormequat at 1,000 to 2,000 ppm, applied in the nursery as a soil drench to 10 day old seedlings, gave good results; these seedlings were transplanted three weeks after treatment. Treated plants of most cultivars were compact in habit with concentrations of 2,000 ppm and they did not require staking. These plants produced flowers and fruits 10–12 days earlier than the control; fruits were also uniform in size and colour with very little damage due to skin cracking. However, the number of fruits per plants was reduced with applications of cycocel at 2,000 ppm and lower yields per acre were obtained. This loss was overcome by planting a higher number of plants per acre; a spacing of 24 inches x 9 inches was recommended. This planting density is acceptable, due to the compact habit of the treated plants.

      Treated plants were also largely resistant to "Damping-off" diseases and drought. The cost of the application of chlormequat per acre is US dollars 2.00 which is considerably cheaper than the cost of staking plants. There was also an increase in the percentages of soluble solids and reducing sugars at applications of 1,000 and 1,500 ppm but the pH of the fruits remained unchanged.

    2. Okra (Hibiscus esculentus). Chlormequat at concentrations of 1,000 and 1,500 ppm, sprayed on seedlings when the first true
Sinnadurai, S. (1973). THE EFFECT OF PLANT GROWTH REGULATORS ON SOME VEGETABLE CROPS IN GHANA - A REVIEW OF RECENT RESEARCH. Acta Hortic. 33, 121-122
DOI: 10.17660/ActaHortic.1973.33.14
https://doi.org/10.17660/ActaHortic.1973.33.14

Acta Horticulturae