Family: PISTACIACEAE
Pistacia vera (pistachio)
A native of western Asia and Asia Minor, the pistachio is a long lived, relatively slow growing, deciduous tree, with a spreading growth habit, eventually reaching a height of 10 m.
It prefers a deep, fertile soil, but is remarkably adaptable to different soil types, as long as there is sufficient depth of soil and it is well drained. It will tolerate a wide range of pH in the soil and will tolerate about twice the degree of salinity as most other fruit and nut trees. Its climatic requirements however, are more specific. It requires long, hot summers to produce the best crops, plus winter chilling, needing mean daily temperatures below 7 - 10°G in the winter. Spring frosts at around the time of flowering are likely to interfere with setting. The pistachio is drought tolerant, although responds well to irrigation.
Nutritional composition of the pistachio per 100 grams of edible portion is: Water - 5.3%, Energy - 594 calories, Carbohydrate -19.0 g, Fat - 53.7 g, Protein - 19.3 g, Ash - 2.7 g, Calcium - 131 mg, Potassium - 972 mg, Magnesium - 158 mg, Iron - 7.3 mg, Phosphorous - 500 mg, Vitamin A - 230 I.U., Thiamin - 0.67 mg, Niacin - 1.4 mg.
Trees can begin to crop in years 5 - 7 , but may take up to 15 years before nuts are produced.
They are dioecious, requiring both male and female trees, and flowers are wind pollinated. Usually, pistachio trees bear a crop biennially and are capable of producing in excess of 50kg of nuts per tree. The nuts comprise a single large seed inside a thin shell, which is surrounded by a thin hull. They ripen in early Autumn, when the fleshy hull becomes soft and partly separates from the shell. The shell splits open to reveal the kernel inside. Nuts are harvested either by being knocked off with sticks, picked by hand or shaken by a mechanical shaker. The nuts are then hulled and dried as quickly as possible to prevent spoilage of the kernels.
Trees are propagated by grafting onto the rootstocks of two other species of pistachio (P vera is not recommended as a rootstock as it grows slowly with a straggling habit). Spacing of trees is about 8 m, with the ratio of male to female cultivars being 1 to 9. Pistachios naturally form low bushy trees which are difficult to manage, so have to be trained to encourage a strong trunk and up to 5 main limbs.