Germination of plants

Certain fungal metabolites have also been found to induce the germination of plant parasites effectively. Cotylenins 21 and 22 and fusicoccins 23 and 24 are effective inductors of S. hermonthica and O. minor seeds germination (Fig. 6.5). However, the activity of these compounds is lower than that of strigolactones (ED50 around 10 pM), the free alcohols 22 and 24 being the more active compounds.57... 

Herbicidins. Five adenine nucleosides, herbicidins A, B, E, F, and G (30—34), have been isolated from the culture filtrates of S. sagamonensis No. 4075 (1,4) which also produces ara-A and 2 -deoxycoformycin. The herbicidins contain a tricyclic dodecose. They inhibit dicotyledonous plants, germination of plant seeds, growth of blue-green algae, and fungi. 

Pigments of eyes, wings etc. of Arthropods, light screen Inhibitor of the germination of plant seeds... 

Some importance is attributed to the MaiUard reaction during the germination of plant seeds due to the increased availabihty of free amino acids and sugars. Several intermediates of the MaiUard reaction are apparently appUed as stimulants of germination. 

Palma-Guerrero, J., Jansson, H. B., Salinas, J., Lopez-Llorca, L. V. Effect of chitosan on hyphal growth and spore germination of plant pathogenic and biocontrol fungi. JAppl Microbiol 200, 104(2), 541-553. 

In addition to inhibitory chemicals which enter the plant from the external environment, many endogenous inhibitors appear to function as regulators of seed germination and plant growth and development. The interrelationships between endogenous inhibitors and growth promoters such as the auxins, gibberellins, and kinins remain to be elucidated. 

Unidentified Stimulators. Growth-inhibitory materials in, or secreted by, plants have for the most part been emphasized in this paper. However, root secretions of many plants also contain constituents required for the germination of seeds of angiospermous root parasites (Striga, Orobanche, Alectra, and Sopubia genera). This phenomenon has been reviewed by Brown (17). Striga asiatica was identified for the first time in the western hemisphere in 1956 in two... 

P. Sathiyamoorthy, Identification of vanillic and p-coumaric acid as endogenous inhibitors of soybean seeds and their inhibitory effect on germination. J. Plant P/m-w/. /id 120 (1990). 

The term allelopathy was coined by Molisch in 1937 Q). Presently, the term generally refers to the detrimental effects of higher plants of one species (the donor) on the germination, growth, or development of plants of another species (the recipient). Allelopathy can be separated from other mechanisms of plant interference because the detrimental effect is exerted through release of chemical inhibitors (allelochemicals) by the donor species. Microbes associated with the higher plants may also play a role in production or release of the inhibitors (2). 

Aliphatic compounds Several water-soluble simple organic acids and alcohols are cannon plant and soil constituents. They include methanol, ethanol, n-propanol and butanol (40), and crotonic, oxalic, formic, butyric, lactic, acetic and succinic acids (41, 42), all of which inhibit seed germination or plant growth. Under aerobic conditions, however, aliphalic acids are metabolized in the soil and therefore, should not be considered a major source of allelopathic activity (40). 

Encecalin (I) causes a dwarfing of lettuce shoots at concentrations from lOppm and up. On the other hand, eupatoriochromene (II) causes very little dwarfing of the seedling but does inhibit germination of lettuce at lOOppm and above. The concentration of these two chro-raenes in yellow starthistle may indeed allow for some effect to be exerted on the surrounding plant community. 

The effects of the above constituents of A. palmerl on the germination and growth of a number of plant seeds are discussed by Dr. J. M. Bradow in her chapter of this book. 

That compounds of the potency of liriodenine are present in plant tissues underscores the potential of plants to affect dramatically other organisms in their environment. Release of liriodenine or similarly potent agents from decomposing plant materials may significantly modify the microbial flora of the root zone. This in turn may have direct and indirect effect the plants which will germinate and grow in the affected soil, the classical allelopathlc effect (11). 

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