Plant Growth Regulation

, Volume 20, Issue 3, pp 179–183 | Cite as

Mepiquat chloride (PIX)-induced changes in photosynthesis and growth of cotton

  • A. Ramachandra Reddy
  • K. R. Reddy
  • H. F. Hodges


Mepiquat chloride (N, N-dimethylpiperidinium chloride), well known as PIX, is a potential systemic plant growth regulator. The effects of PIX on plant height, stem elongation, leaf area, net photosynthetic rates, chlorophyll content, sucrose and starch levels, and RuBP carboxylase activity in cotton (Gossypium hirsutum L. cv. DES 119) plants were measured. PIX was sprayed (0, 7.65, 15.3, 30.6 or 61.2 g active ingredient ha−1) on the plants at first square (25 days after emergence) and measurements were made at frequent intervals. Plant height was clearly reduced by PIX. The total length of vegetative branches and fruiting branches was 40% and 50% less than the control. Total leaf area in PIX treated plants was 16% less than the control. Net photosynthetic rates were 25% less in PIX-treated leaves. PIX treated leaves had more chlorophyll content. The activity of RuBP carboxylase was decreased in PIX treated plants. Starch accumulation was noticed in PIX treated leaves while sucrose content was not changed. The data reported here suggest that reduced growth responses induced by PIX results in partial loss of photosynthetic capacity in cotton at least up to 20 days after application of the growth regulator.

Key words

cotton growth mepiquat chloride photosynthesis PIX RuBP carboxylase 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Arnon DI (1949) Copper enzymes in isolated chloroplasts: polyphenol oxidase in Beta vulgaris. Plant Physiol 24: 1–15Google Scholar
  2. 2.
    Bergmeyer HU (1963) Methods of Enzymetic Analysis. New York, USA: Academic Press, 117 pGoogle Scholar
  3. 3.
    Cairns AJ (1987) Colorimetric microtiter plant assay of glucose and fructose by enzyme-linked formazan production. Applicability to the measurement of fructosyl transferase activity in higher plants. Anal Biochem 167: 270–278Google Scholar
  4. 4.
    Cathey GW and Meredith WR (1988) Cotton response to planting date and mepiquat chloride. Agron J 80: 463–466Google Scholar
  5. 5.
    Fernandez CJ, Cothern JT and McInnes J (1992) Carbon and water economies of well-watered and water-deficit cotton plants treated with mepiquat chloride. Crop Sci 32: 175–180Google Scholar
  6. 6.
    Gausman HW, Walter H, Stein E, Rittig FR, Leamer RW, Escobar DE and Rodrignez (1979) Leaf CO2 uptake and chlorophyll ratios of PIX-treated cotton. In: Proc 6th Ann Meeting of Plant Growth Reg Working Group, Las Vegas, pp 117–125. USA: PGRWG, Longmount, COGoogle Scholar
  7. 7.
    Geiger DR and Servaites JC (1994) Diurnal regulation of photosynthetic carbon metabolism in C3 plants. Annu Rev Plant Physiol Plant Mol Biol 45: 235–256Google Scholar
  8. 8.
    Hake K, Kerby T, McCarty W, O'Neal D and Supak J (1991) Physiology of PIX. In: Physiology Today, Vol. 2, No. 6. Memphis, USA: National Cotton Council of AmericaGoogle Scholar
  9. 9.
    Hendrix DL and Peelen KK (1987) Artifacts in the analysis of plant tissues for soluble carbohydrates. Crop Sci 27: 710–715Google Scholar
  10. 10.
    Hewitt EJ (1952) Sand and water culture methods used in the study of plant nutrition. In: CAB Tech Commun 22, p 189. Farnham Royla, UK: Commonwealth Agric BureauGoogle Scholar
  11. 11.
    Kerby TA (1985) Cotton responses to mepiquate chloride. Agron J 77: 515–518Google Scholar
  12. 12.
    Kerby TA, Hake K and Keeley M (1986) Cotton fruiting modification with mepiquat chloride. Agron J 78: 907–912Google Scholar
  13. 13.
    Lorimer GH, Badger MR and Andres TJ (1977) D-ribulose 1,5-bisphosphate carboxylase/oxygenase. Improved methods for the activation and assay of catalytic activities. Anal Biochem 78: 66–75Google Scholar
  14. 14.
    McCarty JC, Jenkins JN, Shephard RL and Parrott WL (1987) Vegetative growth response of primitive race stocks to PIX. Miss Agric For Exp Stn Res Rep 12: 4Google Scholar
  15. 15.
    McKinion JM, Baker DN, Whisler FD and Lambert JR (1989) Application of the GOSSYM/COMAX system to cotton crop management. Agric Syst 31: 29–33Google Scholar
  16. 16.
    O'Neal D (1988) PIX mode of action. A BASF Wyandotte Corporation Report, pp 1–13Google Scholar
  17. 17.
    Portis AR, Salvucci ME and Ogren WL (1986) Activation of RuBP carboxylase/oxygenase at physiological CO2 and RuBP concentrations by Rubisco activase. Plant Physiol 82: 967–971Google Scholar
  18. 18.
    Ramachandra Reddy A and Das VSR (1986) Correlation between biomass production and net photosynthetic rates and kinetic properties of RuBP carboxylase in certain C3 plants. Biomass 10: 157–164Google Scholar
  19. 19.
    Reddy VR (1993) Modelling mepiquat chloride-temperature interactions in cotton: The model. Comput Elec Agric 8: 227–236Google Scholar
  20. 20.
    Reddy KR, Hodges HF and McKinion JM (1993) A temperature model for cotton phenology. Biotronics 22: 47–59Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • A. Ramachandra Reddy
    • 1
  • K. R. Reddy
    • 1
  • H. F. Hodges
    • 1
  1. 1.School of Life SciencesPondicherry UniversityPondicherryIndia

Personalised recommendations