Background

Almond is a traditional crop in the Mediterranean basin that is experiencing significant expansion worldwide. The United States is the world’s leading producer (1,322,222 t in 2021). The American productivity is very high (2477 kg/ha in 2021) because of efficient cultivation methods, well-adapted cultivars, and the availability of water for irrigation (USDA 2022).

Strong international demand for almonds, generated by the marketing strategy of the United States (led by the Almond Board of California), has contributed to maintaining attractive prices for growers, especially for organic almonds and certain specific cultivars.

The CEBAS Almond Breeding Program has made a notable contribution to the expansion of almond in Spain by obtaining self-compatible cultivars that are either late flowering [Marta and Antoñeta (Egea et al. 2000)] or extra-late flowering [Penta and Makako (Dicenta et al. 2018)]. These cultivars make it possible to cultivate almond throughout Spain, reducing the risk of frost damage (Guillamón et al. 2022). We have also contributed to international expansion, and our cultivars are present in a range of countries—including Portugal, Italy, France, Greece, Morocco, Tunisia, South Africa, Turkey, the United States, Argentina, and Chile—via nurseries that multiply them with a CEBAS-CSIC license.

Depending on the geographical area, there are two types of almonds in the world. Hard-shelled almonds are usually grown in Mediterranean countries, whereas soft-shelled cultivars are mainly grown in the United States, Australia, and Chile. In the Mediterranean countries, the number of cultivars is very high and their origins are highly diverse. In the United States and Australia, on the other hand, there are fewer cultivars, and they are mainly derived from Nonpareil. This increases genetic vulnerability in the face of possible biotic or abiotic problems (Pérez de los Cobos et al. 2021). It would thus be interesting to have soft-shelled cultivars worldwide with the genetic richness of the Mediterranean varieties.

In the CEBAS-CSIC Almond Breeding Program, we have developed two new cultivars that meet these requirements: Florida and Alaska.

Origin

Both cultivars were obtained by traditional breeding, by hand pollination of the female pistil with the pollen of the male progenitors. ‘Florida’ was derived from ‘Antoñeta’ × ‘Marcona’, and ‘Alaska’ from two CEBAS-CSIC advanced selections, ‘D00–078’ and ‘D01–462’. Furthermore, Italian (Cristomorto, Tuono, Genco), American (Tardy Nonpareil), French (Aï, Ferragnès, R1000), and Ukrainian (Primorskii) cultivars were involved in their pedigree (Fig. 1).

Pedigree of ‘Florida’ and ‘Alaska’. In bold, the self-compatible genotypes. OP = open pollination. SP = self-pollination.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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Pedigree of ‘Florida’ and ‘Alaska’. In bold, the self-compatible genotypes. OP = open pollination. SP = self-pollination.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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Pedigree of ‘Florida’ and ‘Alaska’. In bold, the self-compatible genotypes. OP = open pollination. SP = self-pollination.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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The main experimental field of CEBAS-CSIC is located in Santomera, Murcia (southeastern Spain) at a latitude of 150 m; the summers are hot (above 35 °C) and the winters are mild (usually above 0 °C). The soil is quite stony. Mother plants, growing on their own roots, were drip irrigated (∼5000 m³/ha and year) and cultivated following standard phytosanitary treatment procedures (in the winter, spring, and summer), fertilization, and pruning. There were no beehives in the orchards, but bees are usually present during flowering.

Cultivar Characteristics

Florida and Alaska are self-compatible cultivars with high fruit set after passive self-pollination (fruit set with no introduced honeybee pollinators). Self-compatibility was determined by three methods: observing the pollen tube growth along the pistil after self-pollination, polymerase chain reaction allele specific, and bagging branches before flower opening. Both cultivars are soft-shelled (shells can be broken by hand), with a kernel percentage ranging from ∼50% (including the whole shell) to ∼60% (without the outer shell layer) (Table 1). In the hard-shelled cultivars, the inner and outer endocarp layers are usually joined, but they are easily detachable in the soft-shelled ones and the outer layer is usually removed together with the hull.

Table 1.

Main tree, flowering, and fruit characteristics of Florida and Alaska almond cultivars.

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‘Florida’ is early flowering (similar to ‘Nonpareil’) and extra-early maturing (∼3 d before ‘Nonpareil’), so it was designed for warm areas, without risk of frost. It has very high vigor, and a balanced-upright habit and high branching. It is very productive. Production was subjectively scored between 0 (no production) and 5 (maximum production). This cultivar has a light-colored 1.4-g kernel with a low percentage of double kernels (Fig. 2). Fruit characteristics were evaluated in a sample of 25 fruits for several years. Given its flowering time and S-genotype, ‘Florida’ (S₁₁S_f) would probably be a good pollinator for ‘Nonpareil’ (S₇S₈). This would have to be evaluated in specific growing regions.

In-shell fruits and kernels of the almond cultivar Florida.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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In-shell fruits and kernels of the almond cultivar Florida.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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In-shell fruits and kernels of the almond cultivar Florida.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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‘Alaska’ is extra-late flowering (more than 2 weeks later than ‘Nonpareil’) (Table 1) and intermediate ripening (∼2 weeks later than ‘Nonpareil’), so it is suitable for colder areas with risk of frost. It has high vigor and a balanced habit and branching. It is very productive. Its kernels weigh 1.2 g and there is a low percentage of double kernels (Table 1, Fig. 3).

In-shell fruits and kernels of the almond cultivar Alaska.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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In-shell fruits and kernels of the almond cultivar Alaska.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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In-shell fruits and kernels of the almond cultivar Alaska.

Citation: HortScience 58, 4; 10.21273/HORTSCI16904-22

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Both cultivars have been evaluated for more than 15 years at the CEBAS-CSIC experimental station in Murcia (Spain), and for a few years in external experimental orchards (in colder and warmer areas in Spain), which have confirmed their good performance.

The Almond Board of California (ABC) financed the introduction of both cultivars in the United States through the Foundation Plant Services of the University of California. Recently, the ABC and University of California Davis have selected ‘Florida’ for inclusion in the Regional Variety Trials (RVTs) for experimentation in California, among several other American, Australian, Israeli, and Spanish cultivars (Almond Board of California 2020).

We think that these two cultivars could complement the supply of soft-shelled almonds around the world, with the following advantages: 1) the incorporation of floral self-compatibility (mandatory for new cultivars) that favors fruit set and improves the economic profitability of orchards; 2) the different flowering timings allowing for cultivation in areas where Nonpareil is currently cultivated (Florida) and cold areas (Alaska), where early-flowering cultivars are usually damaged by frost, increasing the potential cultivation area; and 3) the incorporation of these cultivars into the market is planned using the “certified” category, which benefits growers by ensuring plant health and genetic integrity.

Because of their genetic background (derived from a more diverse panel of progenitors), our cultivars may have a greater potential to adapt to diverse situations than American cultivars with narrow genetic backgrounds (Pérez de los Cobos et al. 2021).

Chemical Composition

The chemical composition of almonds is increasingly considered an important quality factor. It is a varietal characteristic, although it is somewhat variable depending on environmental and culture conditions.

‘Florida’ and ‘Alaska’ have been chemically characterized for 4 years in three locations by the “Asociación de Fabricantes de Turrón, Derivados y Chocolate de la Comunidad Valenciana” (Spain), under the supervision of the “Consejo Regulador de las IGPs Jijona y Turrón de Alicante.” Table 2 shows the mean values of the two cultivars for the main characteristics analyzed. They have been compared with Nonpareil (the most important cultivar in the world) and Independence (a new self-compatible American cultivar).

Table 2.

Chemical composition of ‘Florida’ and ‘Alaska’ compared with ‘Nonpareil’ and ‘Independence’. Fiber, protein, fat, and sucrose contents (expressed as a percentage) and sterol content in mg/100 g. Ratio between unsaturated and saturated fatty acids (U/S index), and between oleic and linoleic acid (O/L index).

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Fiber content was very high in ‘Independence’ (13.5%) and low in ‘Alaska’ (5.7%). The other two cultivars were very similar to the mean. The protein percentage was similar in the four cultivars, although somewhat higher in Independence.

Significant differences in fat content were observed, and the levels were very high in ‘Alaska’ (60.0%) and low in ‘Independence’ (46.8%). ‘Florida’ and ‘Nonpareil’ had intermediate and similar levels. A high fat content is essential for the production of certain products, such as Jijona Spanish nougat (soft nougat).

All cultivars had a high sugar content, comparable to Nonpareil (5.4%). High sugar levels may be of value for products without added sugars (chocolates, drinks, etc.).

Regarding the ratio between the unsaturated and saturated fatty acids (the U/S index), all cultivars showed similar high values (close to 12%), which shows once again the healthy characteristics of almond oil.

The oleic and linoleic fatty acid ratio was also similar among the different cultivars, although it was somewhat lower in Nonpareil. Some studies show that a high oleic/linoleic index increases the stability of the oil and the quality of the almond and its derived products.

Regarding phytosterols, except for Independence (287.0 mg/100 g), the other cultivars presented high and similar values. Beta-sitosterol is the main sterol in almonds, representing more than 90% of the total sterol content. Phytosterols reduce the absorption of cholesterol.

Overall, ‘Alaska’ stood out for its high fat content, and the composition of ‘Florida’ was quite similar to that of ‘Nonpareil’.

Availability and Registry

‘Florida’ and ‘Alaska’ are the property of the “Consejo Superior de Investigaciones Científicas” and they have been registered in the “Official Register of Plant Varieties” of the European Union’s “Community Plant Variety Office.” Virus-free budwood is available in several countries.