Plant growth depressants

Besides an anticlastogenic activity, some HS appear to possess also an antitoxic activity, i.e., they were able not only to suppress plant growth depression caused by MH and ALA, but also stimulate growth. Peat, leonardite and alluvial soil HS yielded the best results also for the antitoxic activity. 

In plants, a characteristic feature of manganese deficiency is an initial appearance of interveinal chlorotic spots, followed by necrotic spots or brown cork-like lesions and cavities on young leaves. A severe lack of manganese leads to rapid death of the leaves, inhibition of plant growth, depression of inflorescence and fructification, and stunted leaf and root development due... 

The vegetation of Reg soils is generally very poor. Plant growth is restricted to depressions and run-off channels. 

When zinc fertilizers are used on soils deficient in zinc, crop production may be increased even though the zinc concentration in the plant tissues and especially in the seed show no increase. With higher levels of zinc fertilization, the zinc concentration in plants may increase. Some evidence shows that the value of food and feed crops as sources of dietary zinc can be improved by using zinc fertilizers at rates exceeding those required for optimal plant growth. However, very high rates of zinc fertilization can depress crop yields. 

The physiology of metal toxicity in plants has been reviewed by Foy et al. (1978). The most widely described effects of metal toxicity in plants are inhibited root growth, depressed shoot and leaf growth, and general chlorosis of the younger leaves (Bradshaw and McNeilly, 1981 Baker and Walker, 1989). Literature on the relative toxicities of different metals to different species is limited to a few, mostly species-specific studies. 

For further investigation of L-tryptophan biosynthesis, labelled antbranilate waus used. C-labelled anthranilic acid is converted uniformly to L-tryptophan in plant tissues. Furthermore, labelled lAA was formed from 3- 0-L-tryptophan. Both metabolic sequences are subject to interference by indole metabolites (intermediates of lAA biosynthesis) and by phenols. p-Coumario acid - one of the phenolic substances that inhibit cell elongation - depresses the formation of tryptophan from C-anthra-nilic acid, whereas caffeic acid, which enhances cell elongation, stimulates the incorporation of anthranilic acid into tryptophan (Table 2). Thus, one control effect in the action of phenols on plant growth may be influence on L-tryptophan biosynthesis. 

Adverse effects of copper deficiency can be documented in terrestrial plants and invertebrates, poultry, small laboratory animals, livestock — especially ruminants — and humans. Data are scarce or missing on copper deficiency effects in aquatic plants and animals and in avian and mammalian wildlife. Copper deficiency in sheep, the most sensitive ruminant mammal, is associated with depressed growth, bone disorders, depigmentation of hair or wool, abnormal wool growth, fetal death and resorption, depressed estrous, heart failure, cardiovascular defects, gastrointestinal disturbances, swayback, pathologic lesions, and degeneration of the motor tracts of the spinal cord (NAS 1977). 

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