Cultivation of pistachio

Pistachio is one of the most interesting fruit tree ever cultivated by humans. Pistachio (Pistacia vera L.) is by far the most economically important and a member of the Anacardiaceae or cashew family. Naturally occurring population are found in areas where summers are long, hot and dry and winters are moderately cold.

There are many pistachio cultivars for commercial purpose. A good cultivar should produce high yield, large nuts with high natural splitting and desirable kernel quality.

Pistachio trees are small to medium size, bushy, deciduous tree and can grow to 12 m, but are generally a smaller in the cultivation period. Leaves are compound-pinnate, hairy when young and generally with three and sometimes five leaf lets.

Trees are planted in orchards and take approximately 7-10 years to reach significant production. Production is alternate-bearing or biennial-bearing, meaning that the harvest is heavier in alternate years.

Peak production is reached at approximately 20 years. Trees are usually pruned to a size to make harvesting easier. One male tree produces enough pollen for 8-12 nut-bearing females.

The flowering behavior of pistachio trees depends on their location, which can be steppe-forests, steppe or semi-desert.
Cultivation of pistachio

Harvesting of pistachio nuts

Pistachio trees begin bearing the fourth or fifth year after budding. However, a significant crop is not harvested until the seventh or eighth year. At maturity the pistachio hull slips easily off the shell and the color generally turns a pastel shade of crimson. However, some nuts that shaded inside the canopy can be yellow and blank nuts tend to soften in color.

Change in hull color is closely connected with shell slitting and it is important to harvest but when they are fully mature to ensure maximum shell split. There are 7 to 10 days when harvesting can be done without shell-staining occurring.

Pistachios in California are harvested with a shake-catch mechanical harvester and the nuts are placed directly into bins (1.2 by 1.2 by 0.6 m) or trailers.

In some countries and especially for small-scale operations, pistachios are manually knocked or shaken to the ground on tarps, then transferred to bins or other containers for transport to the hulling facilities. A fully mature tree may produce as much as 25 kg of dry, hulled nuts.

Depending upon planting distance and orchard management practices, yields in pistachio orchards could average 2.25 tonnes to 3.35 tonnes per hectare.

Harvesting at optimum maturity, avoiding delays between harvest and hulling, and drying to 4-6% moisture are important factors in insuring good quality of pistachio nuts. The harvested fruit must be hulled and dried within 24 hours to avoid stained shells and aflatoxin contamination.
Harvesting of pistachio nuts