This vegetatively propagated root crop is known variously as taro, dasheen, or coco yam. It is one of the aroids, and was the basis of the agriculture in Papua New Guinea, which is amongst the oldest in the world, dating from about 7000BC. However, it is a labour-intensive crop, and it became only a minor staple, which lacked the potential of a major staple, capable of supporting the growth of cities and the development of a sophisticated civilisation. There is some room for improvement by amateur breeders , mainly by selection within existing cultivar. Colorado potato beetle
See: Leptinotarsa decemlineata. Combine harvesting
Harvesting grain with a self-propelled machine that both cuts and threshes the crop. Combine harvesters usually have a storage bin that can be discharged into a truck moving alongside, while the harvesting continues without a break. Many machines also have a system of chopping the straw and discharging it on to the ground, often in windrows suitable for burning to control pests and diseases. Combine harvesters are used on most temperate cereals, some pulses, and crops such as mustard and canola. Complexity theory
Modern complexity theory divides all systems into the two categories of linear and non-linear systems. The so-called 'hard' sciences, such as chemistry, physics, and astronomy, are based on linear systems, in which the parameters are fixed, are easily measured, and the outcomes easily predicted. The so-called 'soft' sciences, such as all the life sciences, are based on nonlinear systems, in which the parameters are liable to change, are difficult to measure, and the outcomes difficult to predict. For example, the solar system is linear, and we can predict the phases of the moon, and the tides, with great accuracy for centuries ahead. But the weather is a non-linear system and even short-term weather forecasts are notoriously unreliable.
A snooker table is a good example of a linear system. A skilled player can make shots that obey Newton's laws, and that are predictable. But put that snooker table on a moving ship and the game becomes a non-linear system, which is entirely unpredictable.
An essential feature of non-linear systems is the property of self-organisation and this is the basis of the concept of self-organising crop improvement.
See also: General systems theory. Compositae
The botanical family that includes lettuce, sunflower, Jerusalem artichoke, pyrethrum, safflower, chrysanthemums, and daisies. It is characterised by an inflorescence of many small florets in a single disk, usually surrounded by the petals of the outermost florets.
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