Gardening

Pistachio varieties and rootstocks: How to choose the most suitable one

Hello gardeners. In today’s article we are going to give you all the keys to deciding which variety of pistachio and rootstock to choose. We will see how there are female varieties and male varieties , since it is a dioecious plant.

The variety is the part of the tree that will give us the fruits , while the rootstock is the part that provides the root system , that is, the root, which is below the ground. These two decisions are very important for the establishment of the plantation, since making a mistake in this regard can cause serious damage in the future. 

How to choose the pistachio variety?

As we already said in the article on Pistachio cultivation , the pistachio tree is a dioecious species , with male and female trees. The females are the ones that will give the fruit , while the males are only in charge of the pollen , that is, they will not produce fruit. In this sense, when we have to decide on a variety based on the fruits, we will only look at the females and later, we will choose the males.

Most relevant pistachio varieties

There are numerous varieties of pistachio grown throughout the world. The main ones are:

Female varieties

  • Mateur
  • Aegina
  • Larnaka
  • Avdat
  • Kerman
  • Kastel

Male varieties

  • C Special
  • Mateur M
  • M11
  • Aegina
  • Peter
  • Warrior

In Spain the most widespread female variety is Kerman , with Peter variety as male. For this reason, the fact of choosing these varieties is already going to be an advantage, since the knowledge about their behavior is much broader compared to what we have about other varieties.

The fundamental factor to select the type of pistachio is going to be the climate , although we will also talk about others such as the size of the fruit, production of empty fruits, yields, etc.

How does the climate influence to choose the variety?

The biggest determining factor for the choice of the variety is the climate. In this sense, two fundamental criteria have to be used: cold hours and late frosts .

What are the cold hours?

The cold hours are a very common characteristic among fruit trees. When winter arrives, they go to rest ( fall asleep ) until they accumulate all the hours of cold necessary to wake up and start flowering. The cold hours are all the hours of the day when the temperature is below 7ºC. The number of hours required to come out of rest will depend on the variety, with some that need very few hours (early flowering varieties) and others, however, will need many (late flowering varieties) .

Varieties with high cold requirements will be suitable for cold areas, while varieties with lower cold requirements will be chosen for warmer locations.

The importance of late frosts in choosing the variety

It is vitally important that in our area there are no late frosts when the pistachio enters flowering, as it would cause extensive damage to the trees. In this sense, by choosing a late variety, we will also be reducing the chances of suffering a frost when the pistachios are in bloom. Therefore, climatic factors will take precedence over the rest when choosing the variety. 

Climate and female varieties

If the plantation is going to be located in a colder area, such as the northern half of the peninsula, we will choose a later variety such as Kerman or Kastel . For areas with milder temperatures, such as southern Spain, we can choose an earlier variety , such as Mateur , since spring frosts are more unlikely.

Climate and male varieties

Once the female variety has been chosen, we must select the male variety, so we must look at those varieties of males whose flowering period overlaps with that of the females , in order to ensure pollination. In fact, if the male enters flowering a little earlier than the females, it will be even more beneficial.

The turnaround in the pistachio tree

What is the turnaround? The turnaround is a characteristic of many fruit trees, in which one year they produce a large quantity of fruits (year ON), while the following year, this quantity is considerably reduced (year OFF). The pistachio is a fruit tree that has a significant turnaround . Although, this effect can be mitigated with the choice of variety. In this sense, the “best” cultivars would be Larnaka or Avdat and the “worst” would be Kerman, Aegina or Mateur .

Fruit size according to variety

Kerman fruits are larger and in demand in the market, so their ease and sale price are higher than in other varieties. As negative points, it presents an accentuated stubble and a higher percentage of empty fruits, compared to other varieties. Regarding fruit size, a good alternative to Kerman would be Kastel, since they will have similar sizes. Although, the cultivation of this variety in Spain is not very widespread, so its behavior in our region is unknown.

Percentage of empty fruits

The varieties with the lowest production of empty fruits are Larnaka, Avdat or Aegina . As long as we don’t have late frosts, these cultivars can be an interesting option. As already mentioned, the first factor to take into account when choosing the variety is frost.

Productivity

This is an important aspect especially if we are going to produce pistachios in dry land. Under drought conditions, the varieties with the highest yields are Mateur, Larnaka and Aegina . For rainfed production, these varieties would be around 1100 kg / ha, while Kerman would produce about 850kg / ha.

Choice of rootstock. What is the most suitable pattern?

The rootstock, also called the pattern or foot, is the part that will provide the pistachio root system . We call the root system the set of roots of the tree. The types of rootstock most used in pistachio cultivation are Pistacia terebinthus L. (cornicabra), Pistacia atlantica D. and Pistacia integerrima S. , Among others. The use of hybrids is increasingly being used, such as UCB1 , which would be a cross between P. altantica and P. integerrima , which allows us to combine the advantages of both.

The use of rootstocks is necessary to improve some characteristics of the species from an agronomic point of view, for example, resistance to pests, diseases, climate conditions, soil, etc. Below we will analyze the pros and cons of each one to help you decide which one to choose for your garden or plantation.

Pistacia terebinthus L. (cornicabra)

This rootstock is native to Spain and the Mediterranean region in general, which initially is already an advantage because it means that it is adapted to our conditions .

Advantage

  • Good for dry land, with poor and shallow soils.
  • Good absorption of copper, zinc and boron.
  • High resistance to cold.
  • Medium productions
  • Resistant to the presence of limestone in the soil
  • Resistance to nematodes and Armillaria and Phytophtora fungi

Disadvantages

  • It takes longer to go into production
  • Very sensitive to verticillosis, a disease caused by the Verticillium fungus that is very dangerous for pistachios.

Under what conditions would Pistacia terebinthus be recommended ?

This pattern would be among the best options, along with Pistacia atlantica , if our plantation is dry land , with poor and shallow soils . It is also the best alternative for clay soils , as it is the one that best tolerates it. Without a doubt, it is the most advantageous option for cold areas such as Castilla y León. It could also be a good option for organic plantations due to its smaller size compared to other patterns. Although, as we have already said, we must make sure that our soil does not have Verticillium.

Pistacia atlantica D.

Advantage

  • Good pattern for cultivation in dry land and with poor soils, although not as much as Pistacia terebinthus
  • Medium absorption of copper, zinc and boron
  • Cold hardy, but less than Pistacia terebinthus
  • The productions are good, similar to Pistacia terebinthus
  • It is also resistant to the presence of limestone
  • Greater resistance to Phytophtora than Pistacia terebinthus

Disadvantages

  • It also takes time to go into production
  • Like Pistacia terebinthus , it is sensitive to Verticillium
  • Sensitive to Armillaria ( Pistacia terebinthus is resistant)

Under what conditions would Pistacia atlantica be recommended ?

As we have already said, Pistacia atlantica is a good option for dry land or poor soils . However, it will prefer sandy or loamy soils, unlike Pistacia terebinthus , which supports clay content. If our plot is in Castilla y León, it would not be the best option due to the cold; it is more suitable for the southern half of the peninsula . As with Pistacia terebinthus , we must ensure that Verticillium is not present.

Pistacia integerrima S.

The main advantage of this pattern is that it is the only one resistant to Verticillium , in addition to entering production before the rest of the patterns. However, the rest of the characteristics make it unsuitable for most areas of Spain: lower production than previous patterns, less adaptation to poor soils, not recommended in dry land, very sensitive to cold , lower capacity to absorb nutrients, etc. .

So where would it be suitable for? Warm areas , with not too cold winters, no late frosts and soils with serious Verticillium problems .

UCB1 pattern

This pattern results from the hybridization between Pistacia atlantica and Pistacia integerrima , thus achieving the advantages that interest us the most of both. On the one hand, thanks to Pistacia atlantica, we are going to obtain acceptable cold resistance and, on the other, Pistacia integerrima will provide us with resistance to Verticillium.

However, its adaptation to poor or dry soils is not as good as that of Pistacia terebinthus . In contrast, we can say that its production is slightly higher under irrigation than Pistacia atlantica and Pistacia terebinthus . It has lower efficiencies in the absorption of nutrients , so the cost of subscribing will increase. In addition, its greater growth will also increase pruning expenses .

Under what conditions would UCB1 be recommended?

Mainly for cold areas that in turn have Verticillium problems .

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