Thesis (M.S.)--The Chinese University of Hongkong. / Bibliography: l. 79-86.

Two days of light irradiance reduced the levels of endogenous indole-3-acetic acid in mungbean (Phaseolus radiatus) hypocotyls. The important enzymes for IAA metabolic degradation are peroxidases and laccase. Peroxidase activity of mungbean hypocotyls was enhanced sevenfold by light. Laccase activity also remarkably increased after illumination. The lignin content in mungbean hypocotyls were enhanced twofold by light treatment. The inhibition of mungbean hypocotyls growth induced by light might be due to the decline of endogenous IAA, which was degraded by cationic peroxidase. The high level of lignin were correlated with the increased anionic peroxidase activity in light-treated tissues.

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 133-138).

published_or_final_version / Zoology / Master / Master of Philosophy

Thesis (M. Phil.)--University of Hong Kong, 2008. / Includes bibliographical references (leaf 74-85) Also available in print.

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Intact dark- and light-grown mung bean (Vigna mungo L.), black bean (Phaseolus vulgaris L.), pea (Pisum sativum L.) cowpea (Vigna unguicul a ta (L.) Wa lp.) and squash (Cucurbita pepo L.) seedlings on hydroponic medium were osmotically stressed by exposing their roots to PEG 8000 of various concentrations (-0.2 to -0.6 MPa) to determine stress effects on growth and tissue water status. Growth of dark-grown mung bean hypocotyls ceases within 40 sec upon exposure to any level of stress, and resumes within 10 to 45 min. Growth of all other seedlings were measured usually after 3 to 24 h stress, and in 3 h, elongation is inhibited in dark-grown and is stopped in light-grown tissues. In dark-grown mung bean, black bean and squash hypocotyls and pea epicotyls, growth rates after 24 h stress were found to be proportional to the Ψ of the medium. In mung bean hypocotyls, growth stopped before any change in Ψ or Ψ(π) occurred in the growing region. In this tissue and also in dark-grown squash hypocotyls, pea epicotyls, and in lightgrown cowpea hypocotyls, equivalent reductions in Ψ and Ψ(π) were evident in the growing region after 3 h, so turgor remained constant. In other species, osmotic adjustment with turgor maintenance was evident after 24 h in both the growing and expanded regions. The results with mung bean hypocotyls provided the first demonstration that stress causes an almost instantaneous stress-caused cessation of elongation in dicots. Since data from all plants showed that stress causes growth rate inhibition or cessation without a concomittant decrease in Ψ(p), it is concluded that turgor is not the factor regulating growth. More likely, stress-caused growth and water status changes are responses to an earlier signal, such as a stress-caused reduction in the apoplastic Ψ.

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 92-101).

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Thesis (Ph. D.)--University of Hong Kong, 1997. / Includes bibliographical references (leaves 145-155).