Pollination in the pistachio and characteristics of its flowers

In this article we are going to deal with an interesting and unknown topic, such as pollination in pistachio , the characteristics of its flowers and its influence on the fruit. Also how the climate affects this process.

Plantation in the pistachio

When a pistachio plantation is made, we start by planting the rootstock. Your choice has to be made based on the soil and agronomic practices that are carried out in each plantation. We must also take into account that the varieties are hybrids resistant to verticillosis , a fungus that lives in the soil and especially affects pistachios in humid or flooded areas.

When they are ready to graft, we have to put the scions that are female and male. The distribution of pistachio has already been discussed in another article and it must be a male for every 9 females approximately.

Flowers and pollination in pistachio

Yemas de una flor de pistacho
Types of buds

The flowers arise from a meristem or stem cell, which is continuously divided in a spiral with a golden angle of 137.5º, forming young and embryonic tissue and located in the apical buds of a two-year-old stem if it is male tree and one year old if female. The result is fluorescence, that is, groups of many flowers.

When pruning we must take this into account so as not to eliminate those that are going to bloom, because once fertilized the female flowers are the ones that give rise to the pistachio fruit.

Brotes de flor de pistacho
Pistachio flower buds from the meristem

Most of the flowers are hermaphrodites , but that of the pistachio is dioecious. Male and female flowers are very different.

Parts of hermaphroditic flowers

They have the feminine and the masculine part in the same flower , this favors fertilization.

Parts of the hermaphrodite flower
Parts of the hermaphrodite flower

Pistachio flowers for pollination-Dioecious male

Flores de pistacho macho
1-Clusters of male pistachio flowers 2-Different shades of the clusters, depending on the age of the shoot. 3-Arrangement of the clusters in the shape of a pineapple. 4-Clusters without pollen and leaf buds.

Male Pistachio Flower Outline

Male pistachio flower
Male pistachio flower

Flowering of the male pistachio occurs after the winter break and before the female pistachio. At the end of the cold hours, flowering begins. If these are shortened, it can be anticipated and that there is a problem of time between the flowering of these and the female flowers that starts later.

Characteristics of the male pistachio flower

Male pistachio flower
Male pistachio flower
  • 2 bracts to protect the flower.
  • 1 chalice with 5 lobes.
  • 2, 5 or 8 stamens with short filaments, with tetragonal anthers filled with pollen.
  • Pollen contains vegetative and germinative progenitor cells , it is somewhat ovoid spherical in shape and yellow in color. It is covered by an inner layer called intina and an outer layer called exin which has one of the most resistant substances that exist in nature and allows it to reach the ovary perfectly without being altered. by external factors that it finds, physical, chemical or biological. It also has 3 germinative pores that promote fertilization.
  • It has no petals or ovary.

(Recall that 1, 1, 2, 3, 5 and 8 are numbers in the Fibonacci series).

Partes del grano de polen del pistacho- Polinización del pistacho
Pistachio pollen grain parts

The flowers form clusters that are about 65 mm long and have about 500 flowers. The color is greenish and somewhat brown grouped in clusters and arranged according to the golden angle.

Female dioecious flowers

Female flowers are totally different from male ones, both in form and content. They reproduce from the mother cell (meristem), after the male cells and in shoots of one year.

Characteristics of the female pistachio flower:

  • 2 bracts to protect the flower.
  • 1 calyx with 2 or 5 lobes.
  • 1 supero ovary, ovoid in shape, that is, located above the flower support, with 1 ovule.
  • 3 styles.
  • 3 flattened stigmas, purple in color and fluff border.
  • It has no corolla.
  • Its size is larger than male flowers.
  • It has no stamens.
Parts of the female pistachio flowe
Parts of the female pistachio flowe

Clusters of about 200 flowers are formed with a length of 75 mm. If we observe a female flower cluster with a magnifying glass, we can observe this structure.

(Again in its formation we have the Fibonacci numbers 1, 1, 2, 3).

Flor femenina de pistacho
1-Brote de flor femenina. 2-Empiezan a desarrollarse los pistilos. 3-Primeros estigmas y brotes de hojas. 4-Varios racimos de flor femenina y de hojas.

Pistachio pollination

The fact that the pollen moves to the ovary is known as pollination and it should be done by the wind, insects are not favorable because they are attracted only by male flowers. They would not carry the pollen to the female ones.

Pistachio pollination begins when the anthers that enclose the pollen open and begin to release it for about 4 days.

Distribution of male and female pistachios
Distribution of male and female pistachios

For a good pollination of the pistachio to occur, several factors must be met:

  • Pollen dispersion by the wind. In its absence it is not easy for it to reach the feminine flower.
  • That the pollen meets the stigma of the female flower.
  • It is very important that it does not rain on pollination days because pollen is destroyed.
  • Also that the trees are strategically located so that they reach the largest number of female flowers that will come out a few days later.
  • Have early, mid and late pollinating male pistachios. Or in the same tree the three grafted varieties.
  • That the trees are well nourished so that they produce more pollen.
  • Los árboles machos deben tener más altura que las hembras. Eso se consigue con una poda adecuada.
  • Cover the north and southwest area with male pistachios because the wind usually comes from north-south or southwest-southeast direction.
  • In the days after the pistachio pollination, the plantation should have a humid environment, this makes germination start in a matter of hours.
  • Flowering begins before the first leaves sprout. Normally late March, early April.

The correct pollination of the pistachio guarantees a good harvest !!



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