Pomegranate: a fruit with unexpected virtues

Pomegranate, a fruit with numerous health benefits, offers good income opportunities for farmers. Needed for creating optimum conditions for cultivation is the use of machinery and equipment for laying mulch on the soil, harrowing and weeding as well as topping the plants and the distribution of plant treatment products

The cultivation of Pomegranate is arousing growing interest also in Italy, especially in the Mezzogiorno, the south, mainly in the Puglia and Sicily regions for obvious climatic reasons. The plant features leathery leaves which are always green in their habitat but in the Italian climate tend to become deciduous. The fruit is big and round, 10 to 12 cm in diameter, with tough skin often yellow or light red and inside are the seeds grouped in chambers separated by membrane which is not edible. The edible parts of the fruit are the seeds and the bright red layer which contains the seeds with a bittersweet flavor. 

 

The plant

The site must be well exposed to sunlight but protected from strong winds and the best soil would be deep and fresh with a medium mix or tending to sandy with pH close to neutral and well drained because the pomegranate does not tolerate standing water.

For this reason, traditional plowing for breaking up the soil, typical for tree crops is required and it would be a good idea to incorporate coarse ingedients, to facilitate drainage of excess water, along with organic fertilizer, perhaps 1.5-2 t/hectare of manure, if the soil requires this. The most common way to avoid standing water is to plant on raised beds and lay mulch along the rows under plastic film of the right thickness. It is important to ensure that the plastic is white to maximize the reflection of light for improving the color of the lower half of the fruit. This method also avoids overheating the roots and the underground irrigation pipes and the formation of alghe inside the pipe which could impede the flow of water. Furthermore, the mulch counters the emission of suckers.

In this connection, what can be useful for planting are raised beds and mulch usually adopted in horticulture applied separately or in combination.

Bedding is done with young shoots grown in pots, almost always obtained by multiple  cuttings, at a distance of 3.5 to 4 m apart in rows spaced 4 to 6 m apart for a density of planting of between about 450 to 700 plants/ha. Each hole possibly made by independent drilling or by a tractor PTO is then filled with a mix of soil, sand and a well seasoned organic compound.

 

Crop care and forms of training

Especially during the first year of the crop the terrain must be kept clear of weeds, best done through mechanized operations such as surface harrowing and weeding rather than with the use of chemical plant treatment products. Fruit production begins 2 or 3 years after planting and can continue satisfactorily for up to 30 years. After bedding, the tempertatures of the environment will be high so effective emergency irrigation will be necessary for the young plants while avoiding wetting the trunks. As these cultivations are usually practiced in hot climates, the pomegranete shows great resistance to drought as well as to salinity (less so only compared to the date palm) and to chlorosis. These characteristics make the fruit bearing plant useful for increasing the value of marginal lands, arid, stony or rich in rock fragments. In any case, water is needed for fully optimizing production. The solution often applied for this is the use of drip irrigation booms equipped with Ø 16 mm nozzles. According to the climate and the years, the water requirement of a cultivation comes to between 4,000 and 10,000 m³/ha per year. Useful for this is monitoring the humidity levels of the soil with a tensiometer. Fertilization can be performed either with organic fertilizer, such as well seasoned manure, or balanced NPK type mineral fertilizer in the phase of plant rooting and then nitrogen in full production. Common centrifugal slurry and fertilizer spreaders are useful for granular forms of compost. If an irrigation plant is installed locally, the plant can also be used for fertilization.

In nature the pomegranete is a deciduous shrub which generates numerous basal shoots. Aside from the esthetic features of the plant, these shoots must be eliminated in a commercial crop to maximum the development of the crown and the main branches. The operation for this is manual, facilitated by suitable scissors or shears. Training of the plants can either be in the classic pot shape or overturned umbrella with support beginning at about 0.8 to 1 m work to make the crown less dense and separate the branches within for allowing the light to enter sufficiently to bring the fruit to maturity. To support the branches when the fruit is dense, large and heavy, a good idea is to set up Y-shape stakes during planting, often in galvinized steel, and then run sturdy wires along the two upper projections of these stakes. 

To allow the circulation of air and entry of light inside the canopy of especially vigorous varieties it might be necessary to step in with alternating or disc toppers to thin out the development of the canopy. On the other hand, in some cases the trend is training in the shape of the palm which does not comply with the natural tendency of the plant but is well suited for dry pruning and green topping and especially for harvesting.

Defence and harvest of the product

In general, the new buds and the most tender parts of the plant come under attack by green aphida, red spiders, scale insects, thripidae and striped months whereas the pathologies of vegetable origin are botrytis bunch rot and cercospora beticola. In these cases the most suitable plant treatment products are distributed with common sprayers, with a preference for air blast sprayers because the flow of air can be oriented by fully opening the nozzle to penetrate the vegetation with greater efficiency for the distribution of the product mix. 

The fruit is ready for harvest when the color of the outside skin turns yellor or deep red, according to the specific characteristics of the cultivar. Considering the typical stages of maturity and the size of the fruit, these operations can be performed manually with the help of scissors or shears. Shears are best if they are electronic for providing greater safety and ensuring less fatigue. The harvested fruit is deposited in crates which are collected aboard a trailer for transporting the harvest to the farm.

The fruit harvested will keep well for 4 to 8 weeks in refrigerated cells or in a dry location at about 5 °C. In the third year of the plants produced can reach 15 t/ha and increase up to 45 t/ha at full regime in the fifth year.

As regards income, without getting into detail, expenses involved in planting the cultivation come to about € 10,000 to 15,000/ha and the gross price of the product is some € 600 to 800 /t. Thus a conservative estimate of Gross Salable Production (GSP) is about € 18,000 to 24,000 at productivity of 30 t/ha.   

BOX: The many benefits of pomegrante

The Pomegranate (Punica granatum), revered since ancient times as a symbol of health, abundance and longevity, originated in Persia. The mature yellow-green fruit with red areas and a tough outer layer produces edible seeds which sometimes take up the entire inside and are separated into cavities by membranes. The crunchy, juicy seeds have a acidic, bittersweet or sweet taste. In Italy only the sweet and bittersweet cultivars suitable for fresh consumption are cultivated: the Dente di Cavallo (Horse Teeth), Neirana, Profeta Partanna, Selinunte, Ragana and the Racalmuto but though the most well known are the Wonderful and the Akko, featuring excellent oganoleptic qualities. The plant has a great ornamental appearance, especially the trees with twisted trunks which are often grown in parks and gardens as single plants or in groups especially for creating hedges and bordure. Aside from the color pigment obtained from the epidermis and roots, the edible pomegranate features a high content of flavonides – a group of plant metabolites thought to provide health benefits through cell signalling – and potent antioxidants, as well as a wealth of mineral salts calcium, potassium, magnesium, phosphorous and sodium, vitamins A, groups B and C and fiber and sugars. A glass of pomegranate juice obtained by squeezing the seeds has three time more flavonoides  than red wine, green tea, blueberries, and cranberries. The pomegranate possesses a number of therapeutic properties recognized by modern medicine as having an anti-cancer effect, especially for tumors, inhibiting breast cancer, prostate cancer and lung cancer thanks to the elevated content of ellagic acid. A content of the fruit also acts as a natural anti-coagulant to counter the formation of atherosclerotic plaque and control LDL, the bad cholesterol, and to the benefit of other maladies.