Macadamia
Macadamia (Macadamia integrifolia) is one among the limited number of well-known tropical nuts of the world. It is delicious and nutritious nut indigenous to the eastern Australia. It is also called Australian nut or Queensland nut and is popularly grown in Australia, Hawaii, California, Florida and South Africa. Cultivation of macadamia has been attempted with good success in some isolated orchards in Kerala, Tamil Nadu, Karnataka and Orissa. Trees of macadamia are evergreen and grow as high as 10 m. M. integrifolia and M. tetraphylla are cultivated but M. integrifolia is more common and known as smooth shelled type which has almost spherical, smooth surface kernels while M. tetraphylla is known as rough-shelled type and produces slightly elliptical or spindle shaped kernels with pebbled surface.
The edible part, a white cream coloured kernel or embryo is enclosed in one piece very tough spherical brown seed coat or shell which is surrounded by a green, fibrous pericarp or husk. On an average, a fruit weighing 20g has 10g seed and 3g kernel. The macadamia nut resembles cashew in taste but is more oily and globular in shape. The kernels contain relatively large amounts of protein (about 10%) and oil (about 75%). Macadamia nuts are considered a good source of calcium, phosphorus and iron.
Climate and soil
Varieties of M. integrifolia thrive best in subtropical conditions with high summer and low winter temperature, while of M. tetraphylla and hybrids of both the species prefer mild winter condition. Frost-free regions receiving an annual rainfall of about 120cm are well-suited for growing this nut. Experimental evidences shows that macadamia puts up optimum tree growth at 25°C. The sites having long dry season and well-drained sandy loam light soils with 5.5–7.5 pH may be preferred for the macadamia cultivation. Trees have to be protected from strong winds. Generally it comes up well where guava and orange thrive well.
Varieties
Although a good number of varieties have been developed, varieties that are well-suited to one area do not necessarily do well in other regions. Many varieties and hybrids have been selected in Hawaii, California, Australia and South Africa, considering their growth, production, disease resistance, kernel yield, processing characteristics and quality. Some of the notable ones are: Kakea, Ikaika, Keaau, Keauhou, Kau, Purvis, Makai and Mauka (M. integrifolia); Greber, Renown, Anamour, Mammoth, Sewell and Probert 2 (M. tetraphylla) and Beaumont, Nelmak I and Nelmak 2 (hybrids). It is better to plant at least 2 cultivars in an orchard, although self-pollination occurs. Kakea and Keaau grow well under Bangalore conditions and good scope exists to test more number of recent standard cultivars.
Propagation
Although macadamia nut can be propagated by seeds, the commercial production of nut is almost exclusively from grafted trees of known varieties. Seedling trees have proven to be unsatisfactory due to great variation in productivity and kernel quality. They also have longer juvenile phase and sometimes produce bitter nuts with low oil content. The grafted trees produce 3–4 times more nuts on an average, providing 15% higher kernel yield. Macadamia is propagated by wedge grafting on seedling rootstocks. The well mature husked nuts should be used for raising the rootstocks. In-situ grafting can also be practised, if more attention and care are taken.
Macadamia (Macadamia integrifolia) is one among the limited number of well-known tropical nuts of the world. It is delicious and nutritious nut indigenous to the eastern Australia. It is also called Australian nut or Queensland nut and is popularly grown in Australia, Hawaii, California, Florida and South Africa. Cultivation of macadamia has been attempted with good success in some isolated orchards in Kerala, Tamil Nadu, Karnataka and Orissa. Trees of macadamia are evergreen and grow as high as 10 m. M. integrifolia and M. tetraphylla are cultivated but M. integrifolia is more common and known as smooth shelled type which has almost spherical, smooth surface kernels while M. tetraphylla is known as rough-shelled type and produces slightly elliptical or spindle shaped kernels with pebbled surface.
The edible part, a white cream coloured kernel or embryo is enclosed in one piece very tough spherical brown seed coat or shell which is surrounded by a green, fibrous pericarp or husk. On an average, a fruit weighing 20g has 10g seed and 3g kernel. The macadamia nut resembles cashew in taste but is more oily and globular in shape. The kernels contain relatively large amounts of protein (about 10%) and oil (about 75%). Macadamia nuts are considered a good source of calcium, phosphorus and iron.
Climate and soil
Varieties of M. integrifolia thrive best in subtropical conditions with high summer and low winter temperature, while of M. tetraphylla and hybrids of both the species prefer mild winter condition. Frost-free regions receiving an annual rainfall of about 120cm are well-suited for growing this nut. Experimental evidences shows that macadamia puts up optimum tree growth at 25°C. The sites having long dry season and well-drained sandy loam light soils with 5.5–7.5 pH may be preferred for the macadamia cultivation. Trees have to be protected from strong winds. Generally it comes up well where guava and orange thrive well.
Varieties
Although a good number of varieties have been developed, varieties that are well-suited to one area do not necessarily do well in other regions. Many varieties and hybrids have been selected in Hawaii, California, Australia and South Africa, considering their growth, production, disease resistance, kernel yield, processing characteristics and quality. Some of the notable ones are: Kakea, Ikaika, Keaau, Keauhou, Kau, Purvis, Makai and Mauka (M. integrifolia); Greber, Renown, Anamour, Mammoth, Sewell and Probert 2 (M. tetraphylla) and Beaumont, Nelmak I and Nelmak 2 (hybrids). It is better to plant at least 2 cultivars in an orchard, although self-pollination occurs. Kakea and Keaau grow well under Bangalore conditions and good scope exists to test more number of recent standard cultivars.
Propagation
Although macadamia nut can be propagated by seeds, the commercial production of nut is almost exclusively from grafted trees of known varieties. Seedling trees have proven to be unsatisfactory due to great variation in productivity and kernel quality. They also have longer juvenile phase and sometimes produce bitter nuts with low oil content. The grafted trees produce 3–4 times more nuts on an average, providing 15% higher kernel yield. Macadamia is propagated by wedge grafting on seedling rootstocks. The well mature husked nuts should be used for raising the rootstocks. In-situ grafting can also be practised, if more attention and care are taken.
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