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1. The SPA will not be suitable for certification as a seed stand if the heterozygous
individuals (seeds) exceeds 10%.
2. The SPA will not be suitable for certification as a seed stand if the frequency of
the allele corresponding to the “algarrobo negro” (P. nigra, P. flexuosa, P. ruscifolia) in the seed pool exceeds 2%.
The two combined analyses (allozyme and leaf/fruit traits) allow identifying, within
each SPA, individuals to thin with the purpose of increasing the specific purity of
the seeds from the seed stand.
Seed production in Prosopis, as in many forest tree species, is cyclic, so seeds are
not available every year. For this reason, it is important to stock up on seeds during
high production years to ensure their availability for seedling production. Due to
their thick seed coat, the Prosopis seeds stored at 4 °C maintain a high germination
power (80%) for at least 30 years (Verzino and Joseau 2005). The National
Germplasm Bank of Prosopis (BNGP) currently stores 1650 accessions at −18 °C,
corresponding to seeds from 1106 trees or stands. Other ex situ conservation collections are botanical gardens and field trials such as progeny and provenance trials
(e.g., López Lauenstein et al. 2016; Capello 2019; Verzino et al. 2020).
To assess the adaptability of some of the already mentioned seed stands, three
provenance trials were installed in 2011 in three sites in the semiarid region of
Chaco: Laguna Yema (24° 16′ 23.53″ S; 61° 14′ 5.28″ W; 160 m asl), Leales (27°
11′ 12.54″ S; 65° 14′ 37.86″ W; 320 m asl), and Fernández (27° 56′ 16.06″ S; 63°
52′ 26.10″ W; 160 m asl) (Fig. 10.5). The three sites differed in the mean annual
precipitation and the mean annual temperature (Laguna Yema, 703 mm and 22.7 °C;
Leales, 965 mm and 19.9 °C; and Fernández, 575 mm and 20.8 °C, respectively).
The genetic material evaluated in these field trials was seven provenances of
Prosopis alba from different seed stands, two P. alba selections based on the evaluation of three progeny trials (povenances 6 and 7), and one P. chilensis selection
from a natural forest of the Arid Chaco (López Lauenstein et al. 2019).
The performance of this small network of trials was evaluated with periodic measurements of survival, diameter at breast height (DBH), and total height. At the time
of this publication, the latest records are Leales, 2018, 7 years old; Fernández, 2019,
8 years old; and Laguna Yema, 2016, 5 years old. For comparing between sites, the
mean annual increment (MAI) was calculated, dividing the last record, both DBH
and height, by the number of years of each plantation. The main results show significant differences between provenances in both DBH and height growth. In this
sense, provenance N° 1 Prosopis alba “Campo Durán” had the highest MAI both in
height and diameter (Fig. 10.6), standing out mainly in Leales (12.1 cm DBH and
6.24 m in height at 7 years old) and Laguna Yema (12.62 cm DBH and 6.04 m high
at 5 years old). The selection of P. alba from the progeny trials and the selection of
individuals from the natural stand of P. chilensis served as reference for the natural
provenances of P. alba. Provenance N° 7 stands out and corresponds to a selection
of 10 open-pollinated families carried out from the evaluation of more than 200
P. alba families from the entire Chaco region, in 3 progeny trials (López Lauenstein
D. López Lauenstein et al.
1. The SPA will not be suitable for certification as a seed stand if the heterozygous
individuals (seeds) exceeds 10%.
2. The SPA will not be suitable for certification as a seed stand if the frequency of
the allele corresponding to the “algarrobo negro” (P. nigra, P. flexuosa, P. ruscifolia) in the seed pool exceeds 2%.
The two combined analyses (allozyme and leaf/fruit traits) allow identifying, within
each SPA, individuals to thin with the purpose of increasing the specific purity of
the seeds from the seed stand.
Seed production in Prosopis, as in many forest tree species, is cyclic, so seeds are
not available every year. For this reason, it is important to stock up on seeds during
high production years to ensure their availability for seedling production. Due to
their thick seed coat, the Prosopis seeds stored at 4 °C maintain a high germination
power (80%) for at least 30 years (Verzino and Joseau 2005). The National
Germplasm Bank of Prosopis (BNGP) currently stores 1650 accessions at −18 °C,
corresponding to seeds from 1106 trees or stands. Other ex situ conservation collections are botanical gardens and field trials such as progeny and provenance trials
(e.g., López Lauenstein et al. 2016; Capello 2019; Verzino et al. 2020).
To assess the adaptability of some of the already mentioned seed stands, three
provenance trials were installed in 2011 in three sites in the semiarid region of
Chaco: Laguna Yema (24° 16′ 23.53″ S; 61° 14′ 5.28″ W; 160 m asl), Leales (27°
11′ 12.54″ S; 65° 14′ 37.86″ W; 320 m asl), and Fernández (27° 56′ 16.06″ S; 63°
52′ 26.10″ W; 160 m asl) (Fig. 10.5). The three sites differed in the mean annual
precipitation and the mean annual temperature (Laguna Yema, 703 mm and 22.7 °C;
Leales, 965 mm and 19.9 °C; and Fernández, 575 mm and 20.8 °C, respectively).
The genetic material evaluated in these field trials was seven provenances of
Prosopis alba from different seed stands, two P. alba selections based on the evaluation of three progeny trials (povenances 6 and 7), and one P. chilensis selection
from a natural forest of the Arid Chaco (López Lauenstein et al. 2019).
The performance of this small network of trials was evaluated with periodic measurements of survival, diameter at breast height (DBH), and total height. At the time
of this publication, the latest records are Leales, 2018, 7 years old; Fernández, 2019,
8 years old; and Laguna Yema, 2016, 5 years old. For comparing between sites, the
mean annual increment (MAI) was calculated, dividing the last record, both DBH
and height, by the number of years of each plantation. The main results show significant differences between provenances in both DBH and height growth. In this
sense, provenance N° 1 Prosopis alba “Campo Durán” had the highest MAI both in
height and diameter (Fig. 10.6), standing out mainly in Leales (12.1 cm DBH and
6.24 m in height at 7 years old) and Laguna Yema (12.62 cm DBH and 6.04 m high
at 5 years old). The selection of P. alba from the progeny trials and the selection of
individuals from the natural stand of P. chilensis served as reference for the natural
provenances of P. alba. Provenance N° 7 stands out and corresponds to a selection
of 10 open-pollinated families carried out from the evaluation of more than 200
P. alba families from the entire Chaco region, in 3 progeny trials (López Lauenstein
D. López Lauenstein et al.