Root exudate flowering

Chemicals with allelopathic potential are present in virtually all plant tissues, including leaves, stems, roots, rhizomes, flowers, fruits, and seeds. Whether these compounds are released from the plant to the environment in quantities sufficient to elicit a response, remains the critical question in field studies of allelopathy. Allelochemics may be released from plant tissues in a variety of ways, including volatilization, root exudation, leaching, and decomposition of the plant residues. 

Allelopathy is defined as biochemical interactions between one plant or microorganism (alga, bacteria, or virus) and another plant through the production of chemical compounds - secondary metabolites (allelochemicals), which influence, direct or indirect, harmful or beneficial, plant growth and development (Rice 1984). Allelochemicals are present in almost all plants and in many tissues, like leaves, stems, flowers, fruits, seeds, roots, or pollen and may be released from plants into the environment by volatilization, leaching, root exudation, and decomposition of plant residues (Chou 1990). 

The listing of accumulation sites forms an essential part of the tables (under the column head Plant organs ). In particular, attention focuses on the presence of flavonoids in exudates if indicated by the authors (marked with the abbreviation ext., if not clear from a term like bud exudate ). Critical sources are listings such as whole plant which could mean anything from aerial parts to inclusion of roots and flowers. Despite our efforts, we received a single reply only from the authors addressed. Hence the correctness of whole plant was confirmed only for two flavonols isolated from Andrographis viscosula Details on specific accumulation sites and specific accumulation trends will be discussed in the text relating to the respective tables. 

Flavonoids are important secondary metabolites involved in pigmentation of flowers, disease resistance, and so on. Among the flavonoids, kaempferol (67), quercetin (68), and naringenin (69) are most often cited as allelochemicals. (zh)-Catechin was identified in the root exudates from spotted knapweed Centaurea maculosa) as the compound responsible for its invasive behavior.45 The plant uses (-)-catechin (70) as an allelochemical facilitating its invasion and (+)-catechin (71) as a defense compound against pathogens. 

Fig. 6. Influence of flower removal on cytokinin flux in soybean root exudate...

Neither translocation to roots nor root exudates explain the loss. A major part of the losses must be due to the shedding of various plant parts (pollen, flowers, leaves), leaching of nitrogen from aging leaves, and to herbivory these losses (except for windborne pollen) are mostly internal redistributions of the nutrient, as the litter, leaching, and herbivory return the nutrient to soils. But most of the nitrogen lost from tops of plants is due to volatilization of NHs. ... 

We designate as natural all materials that are obtained from natural sources by the application of physical separation techniques such as distillation and extraction. Natural products have been used for many thousands of years as the raw materials of perfumery. Entire plants, flowers, fruits, seeds, leaves, as well as woods, roots, and the resins they exude, are all sources of fragrance materials. Similarly the scent glands of animals such as the civet cat and the musk deer have been used since early civilization to provide perfume for humans. 

Plant material A plant or plant part (e.g., bark, wood, leaves, stems, roots, flowers, fruits, seeds, or parts thereof) as well as exudates thereof. 

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