Fertility restoration

Not surprisingly, azoospermia is a classic consequence of intensive use of anabolic androgenic steroids, and it can be reflected in sterility. A well-documented case has shown that in at least some cases the condition can be reversed and fertility restored by treatment with gonadotrophins (HMG and HCG) (89). 

At any rate, boosting African crop production will require increased use of soil amendments. Natural soil fertility restoration during long fallow periods, as practised in traditional shifting cultivation systems, becomes less and less feasible with rising population pressure. Mineral fertilisers have been key components of strategies to increase crop yields and restore soil fertility (e.g. Quinones et al., 1997), yet their availability and use in SSA remain very low due to lack of production, transport and market infrastructures (Larson and Frisvold, 1996 Dudal, 2002). Nutrient imbalances have resulted in the loss of an estimated 700 kg N, 100 kg P and 450 kg K ha 1 from SSA cropland during the last 30 years, while... 

Schlecht, E. Buerkert, A. Tielkes, E. and A. Bationo (2006) A critical analysis of challenges and opportunities for soil fertility restoration in Sudano-Sahelian West Africa.- Nutrient Cycling in Agroecosystems, in print. 

Cytoplasmic male sterility of sunflower was discovered in 1958, whereby one factor in the cell cytoplasm leads to the male-sterility in all plants of the second generation. However, as a result of the pollination of fertile ordinary lines, plants will stiU bear some fertile progeny. Patrice Leclercq, in France, in 1969, reported on cytoplasmic male sterility obtained in the progeny of a cross of Helianthus petio-laris Nutt and Helianthus annuus. In 1970, fertility restorer lines were found. Two years later, hybrid seeds produced by this system were made available to farmers. In 1976, 80% of the U.S. sunflower harvest had been produced on hybrid seed. 

The production of single crosses or three-way hybrids using cytoplasmic male sterility and nuclear fertility restorer system is widely used. Genic male sterility was used for the production of hybrid seeds in the early 1970s in France and Romania. The first hybrids produced in this way were introduced in the United States in 1972 (4). 

Cytoplasmic Male Sterility. Unfortunately, large-scale mechanical emasculation cannot be applied to all crops of interest. In wheat, for example, the pollen-bearing anthers and female stigmas lay side by side within each floret of a spikelet. Removal of anthers with small, hand-held instruments obviously has utility only for small-scale hybridization experiments. Nevertheless, by crossing a female parent endowed with cytoplasmic male sterility with a male parent that has fertility-restoring genes, one can achieve hybrid wheat seed production. This technology, however, has limitations compared to... 

Rai, K.N. and Thakui R.P. (1995) Ergot reaction of pearl millet hybrids affected by fertility restoration and genetic resistance of parental lines. Euphytica, 83, 225-231. 

Heyn, F.W., 1978. Introgression of restorer genes from Raphanus sativus into male sterile Brassica napus and the genetics of fertility restoration. In Proceedings of the 5th International Rapeseed Conference, Malmo, Sweden, vol. 1, pp. 82-83. 

Male sterility is the inability of the plant to produce functional anthers or pollen, through chromosomal aberrations, gene action, or cytoplasmic influences. Plant breeders make use of cytoplasmic male sterility and pollen fertility restorer genes to take advantage of hybrid vigor and superior performance of the hybrid over the parental fines due to heterosis. Many components critical for commercial hybrid production (Palmer et al., 2001) are lacking for flax a stable male-sterile, female-fertile sterility system a selection system to obtain 100% female plants that set seed normally and can be mechanically harvested and an efficient pollen transfer mechanism from pollen parent to female parent. Considerable research is needed before an efficient, productive, and cost-effective system of hybrid seed production conld be available in flax (Green et al., 2008). 

Therapeutic modalities for amenorrhea are targeted at restoring the normal menstrual cycle. The goals of treatment are to preserve bone density, prevent bone loss, and restore ovulation, thus improving fertility as desired. Amenorrhea resulting from conditions contributing to hypoestrogenism also may affect quality of life via the induction of hot flashes (premature ovarian failure), dyspareunia, and in prepubertal females, lack of secondary sexual characteristics and absence of menarche. 

It pursues a number of aims, such as the production of products which contain no chemical residues, the development of environmentally sensitive production methods which avoid the use of artificial chemical pesticides and fertilisers, and the application of production techniques that restore and maintain soil fertility. 

The primary apphcation for this technology is the cleanup of heavily contaminated soils from abandoned herbicide and pesticide manufacturing sites and mixed petroleum wastes containing both hydrocarbon and heavy-metal contaminants. It also has potential as a remediation technique to restore fertility to agricultural soils suffering from overuse and salt buildup from irrigation. 

Rasmussen, J. O., Nepeper, J. R, Rasmussen, O. S. (1996). Analysis of somatic hybrids between two sterile dihaploid Solanum tuberosum L. breeding lines. Restoration of fertility and complementation of G. pallida Pa2 and Pa3 resistance. Theoretical and Applied Genetics, 92,403 10. 

Fertilization The fusion of the sperm and ovum resulting in the restoration of the diploid number of chromosomes. 

In the shape of agricultural produce of a field, the entire amount of those constituents which have become ingredients of plants is removed from the soil. After a series of years, and a corresponding number of harvests, the fertility of the soil or field diminishes. The change which is found to have taken place in the composition of the soil after harvest, is the probable cause of its diminished or lost fertility. By means of solid and liquid manure, or the excreta of men and animals, the loBt or diminished fertility of the land is restored. Solid or farmyard manure consists of decayed vegetal and animal matters, which contain a certain proportion of the constituents of the soil. The excrements of men and animals represent the ashes of the food consumed, and which has been derived from the supposed soil. The urine contains the soluble, the solid excrete the insoluble constituents of the soil derived from the crops used as food, and reaped from the soil. By adding these to the soil, it recovers those constituents which have been removed from it in the crops. 

Thus the restoration of its original composition Is accompanied by the restoration of its fertility. It is therefore certain that one of the conditions of fertility in a soil, is the presence in it of certain mineral constituents. A rich fertile ground contains more of these than a pour barren one does. 

From land rich in mineral constituents, there may be obtained in one year, or for a series of years, by the addition of ammonia alone, in its salts, or of humus and ammonia, rich crops, without in any way restoring the mineral substances removed in these crops, The duration of this fertility depends on the supply of the availahle mineral constituents existing in the soil. The continued use of these manures produces sooner or later an exhaustion of the soil. If after a time the soil is to recover its original fertility, the mineral substances extracted from it by the crops in a series of years must be again restored. 

Natural and Synthetic Fertilizers Help Restore Soil Fertility... 

NATURAL AND SYNTHETIC FERTILIZERS HELP RESTORE SOIL FERTILITY... 

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