scholarly journals Role of the Seed Coat in Dormancy of Eucalyptuspauoiflora and E. Delegatensis Seeds

1967 ◽  
Vol 20 (6) ◽  
pp. 1237 ◽  
Author(s):  
EP Bachelard
Keyword(s):  
Gibberellic Acid ◽  
Seed Coat ◽  
Gaseous Exchange ◽  
Eucalypt Species ◽  
Phacelia Tanacetifolia

Gibberellic acid promotes the germination of dormant seeds of some eucalypt species including Eucalyptus pauciflora Sieb. and E. delegatensis R. T. Baker. It was suggested that gibberellic acid may stimulate germination by promoting enzymatic weakening of the seed coat (Bachelard 1967) as described for Phacelia tanacetifolia seeds (Chen and Thimann 1964). Previously, Grose (1963) suggested dormancy of of E. delegatensis seeds might be due to the seed coat limiting gaseous exchange.

The role of gibberellin and the hulls in the control of germination in Aegilops Kotschyi caryopses

1974 ◽  
Vol 52 (7) ◽  
pp. 1597-1601 ◽  
Author(s):  
Judith Wurzburger ◽  
Y. Leshem ◽  
D. Koller
Keyword(s):  
Gibberellic Acid ◽  
Seed Coat ◽  
Filter Paper ◽  
Amylase Activity ◽  
Pronounced Effect

Large and small Aegilops Kotschyi caryopses have low α-amylase activity. After imbibition in water a marked increase takes place in α-amylase activity in the large, hulled and dehulled caryopses and only a slight increase in the small ones. Exogenously applied gibberellic acid (GA3) enhances α-amylase activity in both caryopses, and also improves germination of the small, hulled caryopses.Removing parts of the hull from different sites on the palea or lemma of the small caryopses improves germination. The most pronounced effect was obtained when the segment was removed from the palea just above the embryo. When this excised site was covered with a strip of wet filter paper before germination, the resulting germination was essentially similar to that of the non-excised controls.The role of GA3 and seed coat in improving germination of small Aegilops caryopses is discussed.

The role of gibberellic acid in the hydrolysis of endosperm reserves in Zea mays

Planta ◽  
1974 ◽  
Vol 121 (1) ◽  
pp. 67-74 ◽  
Author(s):  
B. M. R. Harvey ◽  
Ann Oaks
Keyword(s):  
Zea Mays ◽  
Gibberellic Acid ◽  
Hydrolysis Of

The role of fractures and lipids in the seed coat in the loss of hardseededness of six Mediterranean legume species

2005 ◽  
Vol 143 (1) ◽  
pp. 43-55 ◽  
Author(s):  
L. W. ZENG ◽  
P. S. COCKS ◽  
S. G. KAILIS ◽  
J. KUO
Keyword(s):  
Seed Coat ◽  
Lipid Content ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Petroleum Jelly ◽  
Physicochemical Changes ◽  
Ornithopus Sativus ◽  
Seed Coats ◽  
Seed Coat Morphology

Changes in the seed coat morphology of 12 annual legumes were studied using environmental scanning electron microscopy (ESEM). The seeds of Biserrula pelecinus L. cv. Casbah, Ornithopus sativus cv. Cadiz, Trifolium clypeatum L., T. spumosum L., T. subterraneum L. cv. Bacchus Marsh, Trigonella balansae Boiss. & Reuter., Trigonella monspeliaca L. and Vicia sativa subsp. amphicarpa Dorthes (morthes.) were examined by ESEM after exposure to field conditions for 6 months, while those of Medicago polymorpha L. cv. Circle Valley, Trifolium clypeatum L., T. glanduliferum Boiss., T. lappaceum L., T. spumosum L., and T. subterraneum L. cv. Dalkeith, were examined after 2 years' exposure. The entry of water into seeds was followed by covering various parts of the seed coat with petroleum jelly and soaking the treated seeds in dyes.As the seeds softened over time, more and larger fractures appeared on the seed coat. Water entered the seed either through fractures, over the seed coat as a whole or through the lens. It is hypothesized that the formation of fractures occurs after physicochemical changes in the seed coat, probably associated with changes in the amount and nature of seed coat lipids.The newly matured whole seeds of M. polymorpha cv. Circle Valley, T. clypeatum, T. glanduliferum, T. lappaceum, T. spumosum, and T. subterraneum cv. Dalkeith were analysed for lipid content in 1997. The seed coats of T. subterraneum cv. Dalkeith and T. spumosum were separated from the cotyledons and examined in detail for lipid content.The lipid content of whole seeds ranged from 48 (T. lappaceum) to 167 mg/g (T. subterraneum cv. Dalkeith). Total lipid of the whole seeds of T. subterraneum cv. Dalkeith and T. glanduliferum declined by about 9 mg/g over 2 years, while in T. spumosum it declined by about 17 mg/g.In contrast, the major fatty acids in the seed coat declined by 0·67 mg/g over the 2 years. Change in seed coat lipids showed a marked similarity to changes in hardseededness for both T. subterraneum cv. Dalkeith and T. spumosum. The results strongly suggest that seed softening is associated with loss of lipids in the seed coat, because lipids have physical characteristics that are altered at temperatures experienced in the field.

Germination of Seeds From the Fruits of Thryptomene calycina (Myrtaceae)

1993 ◽  
Vol 41 (2) ◽  
pp. 263 ◽  
Author(s):  
DV Beardsell ◽  
RB Knox ◽  
EG Williams
Keyword(s):  
Gibberellic Acid ◽  
Sulphuric Acid ◽  
Seed Coat ◽  
Major Site ◽  
Low Concentrations ◽  
Viable Seeds ◽  
Insect Predation

Freshly fallen fruits of T. calycina contained seeds which were completely dormant; none germinated after 200 days at 20°C. Seeds excised with testas intact from fresh fruits were partially dormant; one-third germinated after 60 days. The dormancy of seeds in freshly fallen fruits was imposed jointly by the fruit and the seed. The major site of the dormancy was however the seed coat since tearing part of it away from seeds excised from fresh fruits resulted in rapid and complete germination. Fruits stored dry in a laboratory at 20°C for 90 days were partially dormant. Nicking the distal end of these fruits enhanced germination. Seeds excised from these laboratory stored fruits had 85 % germination, which indicated a reduction in the seed imposed dormancy. Germination of T. calycina was independent of light and, although the fruits contained large amounts of phenolic material this did not inhibit germination. Fruits weathered in the field for at least 2 years contained less viable seeds, presumably because of insect predation, but these all germinated within 50 days at 20°C. Brief washing of fruits in concentrated sulphuric acid increased germination. Germination was not enhanced by treatment with low concentrations of gibberellic acid in the presence or absence of cytokinin.

A basic peroxidase isoenzyme from the grape pedicel is induced by gibberellic acid

1999 ◽  
Vol 26 (4) ◽  
pp. 387 ◽  
Author(s):  
Francisco J. Pérez ◽  
Verónica Morales
Keyword(s):  
Ascorbic Acid ◽  
Gibberellic Acid ◽  
Peroxidase Activity ◽  
Hormone Treatment ◽  
Table Grape ◽  
Guaiacol Peroxidase ◽  
Peroxidase Isoenzymes ◽  
Peroxidase Isoenzyme ◽  
Soluble Peroxidase

Soluble peroxidase activity from pedicels of seedless table grape cv. Sultana was highly stimulated by post-bloom applications of gibberellic acid (GA3) to vines. The increase in peroxidase activity was mainly due to the induction of a basic peroxidase isoenzyme (pI > 9; BPrx-HpI). The activity of two other peroxidase isoenzymes of pI 6.5 and 3.2 was not altered by the hormone treatment. BPrx-HpI was induced by GA3 in pedicels and rachis but not in berries, although in berries peroxidase activity was also stimulated by post-bloom GA3 applications. BPrx-HpI oxidised guaiacol and ortho-phenylenediamine (o-PDA), while the others peroxidases found in the pedicel and in the berry oxidised only o-PDA. Hence, BPrx-HpI was characterised as a guaiacol-peroxidase showing no activity towards ascorbic acid (ASC). The possible role of BPrx-HpI in pedicel lignification and berry-drop caused by GA3 applications to cv. Sultana vines is discussed.

scholarly journals The Role of Testosterone and Gibberellic Acid in the Melanization of Cryptococcus neoformans

2020 ◽  
Vol 11 ◽  
Author(s):  
Jamila S. Tucker ◽  
Tiffany E. Guess ◽  
Erin E. McClelland
Keyword(s):  
Gibberellic Acid ◽  
Cryptococcus Neoformans
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