Читать книгу Biotechnology of Fruit and Nut Crops - Группа авторов - Страница 34

Cashew plantation in several countries is treated as an agroforestry programme rather than a horticultural practice. Most orchards are seed propagated as it is cost-effective compared to pesticide- and chemical fertilizer-dependent vegetative propagation methods (Nadagauda et al., 2005). This has resulted in large areas of senile, unproductive orchards of seedling progeny (Jeeva, 2013). The prime objective of vegetative propagation using rootstocks and scions is to increase the yield potential of plantations by overcoming the challenging factors of endemic diseases and pests. There are three types of scion grafting practised in cashew, namely epicotyl, softwood and top working scions in mature trees. The most popular being the softwood graft followed by epicotyl grafting in 3–4-month-old rootstock seedlings. The selection of the scion is on the basis of the desired characteristics such as improved nut size, nut weight, percentage kernel post-shelling out, red fruit colour, compact canopy, early flowering, easy peeling testa and suitability for drought-prone wasteland or coastal sandy tracts.

BREEDING ACCOMPLISHMENTS. Softwood grafting is today a highly standardized technique in nurseries and has begun to provide farmers with uniform planting material. Over 1,000,000 grafts are produced annually by government nurseries as well as private nurseries in Tamil Nadu, India. Softwood grafting using 60-day-old shoots on seedlings during the months of July–August resulted in high survival (Jeeva, 2013).