Dr. D.V. Bhagat – författare
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2 produkter
2 produkter
E-bok
Engelska, 20144 938 kr
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Many species of aquatic plants are essentially cosmopolitan, meaning that they are widely distributed around the world. Some of the widest distributions are attributable to human activities. Humans have accidentally transported seeds, fruits, or vegetative clones from one pond or watershed to another, but many of the cosmopolitan distributions are attributable instead to birds, particularly waterfowl, which inadvertently transport the plant propagules when lodged in their features or trapped in mud on the feet. Many of the designs exhibited by plants living in water were obvious to early botanists. For example, Agnus Arber published a book in 1920 on aquatic plants, documenting many of the strategies that we still talk about today. Submersed leaves receive low levels of sunlight (PFD) because light energy diminishes rapidly while passing through a water column. Light penetration is especially poor in turbid water with dense surface populations of algae. Such underwater leaves are often so highly dissected that the segments may appear superficially to be macroscopic green algae. It is the aim of this little book to convey, by means of description and illustrations, a knowledge of the more common aquatic plants that are found both in and by the water.
E-bok
Engelska, 20134 489 kr
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Horticulture has a very long history. The study and science of horticulture dates all the way back to the times of Cyrus the Great, King of ancient Persia, and has been going on ever since, with present day horticulturists such as Freeman S. Howlett, the revolutionary horticulturist. The practice of horticulture can be retraced for many thousands of years. The cultivation of taro and yam in Papua New Guinea dates back to at least 6950-6440 cal BP. The origins of horticulture lie in the transition of human communities from nomadic hunter-gatherers to sedentary or semi-sedentary horticultural communities, cultivating a variety of crops on a small scale around their dwellings or in specialized plots visited occasionally during migrations from one area to the next (such as the "milpa" or maize field of Mesoamerican cultures). In the Pre-Columbian Amazon Rainforest, natives are believed to have used biochar to enhance soil productivity by smoldering plant waste. European settlers called it Terra Preta de Indio. In forest areas such horticulture is often carried out in swiddens ("slash and bum" areas). A characteristic of horticultural communities is that useful trees are often to be found planted around communities or specially retained from the natural ecosystem. This encyclopaedic dictionary is a systematic compilation of available information on horticulture science that helps in providing specific information on the cultivation and utilization of these crops to farmers, academicians, students and related user industries.