Propagation And Conservation Of Temperate Fruit Trees By In Vitro Techniques

Propagation and Conservation of Temperate Fruit-trees by in Vitro Techniques

Micropropagation of Woody Trees and Fruits

Global warming, environmental changes, water shortage, and sustainable development are the most up-to-date issues, which have challenged mankind. Researchers worldwide are engaged in addressing some of these problems, including reduction in carbon dioxide accumulation, and enrichment of perennial woody species on the terrestrial ecosystem. About 12 million hectares of the world's forests disappear every year. By 2025, the world population will reach 7. 5 billion, and the forest area will be reduced to well below 50 % of the current area. Reforestation is an important to prevent the loss of forest resources including timber, biodiversity and water resources. Therefore, subsequent volume of reforestation over the deforested land should be followed to safeguard the forests and maintain its size, which will require a continuous supply of planting material. Similarly fruit trees, including tropical and subtropical fruit trees, are consumed both as fresh and in the processed form including juices, beverages, and dried fruits. They are an important source of nutrition e. g. rich in vitamins, sugars, aromas and flavour compounds, and raw material for food processing industries. The production, cultivation and maintenance of tree species provide highly sustainable production systems that conserve soils, microenvironment and biodiversity. Fruit trees have longjuvenile periods and large tree size. In many fruit trees e. g. avocado and others controlled crosses are difficult to make due to massive fruit drop.

Tissue Culture of Trees

1 John H. Dodds The culture offragmen ts of plant tissue is not a particularly new science, in fact as long ago as 1893 Rechinger (1893) described the formation of callus on isolated fragments of stems and roots. The culture of plant tissues in vitro on a nutrient medium was performed by Haberlandt (1902), however, his attempts were unsuccessful because he chose too simple a medium that lacked critical growth factors. Over the last fifty years there has been a surge of development in plant tissue culture techniques and a host of techniques are now avail able (Dodds and Roberts, 1982). The major areas are as follows. Callus Culture Callus is a rather ill-dermed material. but is usually described as an un organised proliferating mass of tissue. Although callus cultures have a great deal of potential in the biotechnological aspects of tissue culture, i.e. secondary product formation, they are not very suitable for plant propagation. The key reason for their unsuitability is that genetic aber rations occur during mitotic divisions in callus growth (D'amato.l965). The aberrations can be of a major type, such as aneuploidy or endo reduplication. It follows therefore that the genetic status of the re generated plants is different from that of the parent type. In general terms this genetic instability is undesirable, but there are occasions when a callus stage can be purposely included to diversify the genetic base of the crop.