See: Helianthus tuberosus. Artificial fertilisers
The term 'fertilisation' has two meanings in agriculture. It can mean sexual fertilisation of either plants or animals, or it can mean manuring of crops. Fertilisers used for manure are divided into the two categories of organic and artificial. Organic manures are either the excrement of farm animals, usually known as farmyard manure (F.Y.M.) or stable dung, bone meal, or quarried deposits of fish-eating bird excrement, known as guano. Artificial fertilisers are produced in factories, usually by a simple modification of natural products, such as atmospheric nitrogen, rock phosphate, or potash. Their constituents are known as N, P, and K, the symbols standing for nitrogen, phosphorus, and potassium. Other constituents may include calcium and magnesium, as well as various minor nutrients and trace elements. Artificial fertilisers are allowed in sustainable agriculture, but not in organic farming. Artificial selection
Genetic selection which is controlled by people, within a genetically diverse population. Artificial selection is the basis of both domestication, and modern plant and animal breeding. See also: natural selection, agro-ecotype. Artocarpus altilis
Breadfruit, which is an ancient domestication and is the staple food in a number of Pacific Islands. Ascomycete
Fungi whose sexual reproduction is by means of an ascus. Many plant pathogen are Ascomycetes, such as the powdery mildews, and apple scab (Venturia inaequalis). Ascospore
A spore produced within an ascus. Ascospores are haploid, being the result of the reduction division (meiosis) of a newly fertilised diploid cell, which is the only diploid component in the life cycle of an Ascomycete. Being the result of meiosis, an ascus usually contains eight ascospores but, in some species, the ascus contains only four, or two ascospores.
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