|Abstract or Summary
- The purpose of this research was to determine whether hybridization
between Amelanchier denticulata. (H.B.K.) Koch and Amelanchier nervosa
(Decaisne) StandL occurs in Oaxaca, Mexico, and to evaluate components of yield
and germination characteristics and seed dormancy of Amelanchier denticulata.
Amelanchier nervosa and Amelanchier denticulata samples and
morphological characters were used to define matrices of individual plants (rows)
and characters (columns), which were then analyzed through ordination procedures.
Likely hybrids were separated between the two species in the first two ordination
axes, suggesting a hybrid origin of three collections: Teotitlán (1), Teotitlán (2),
Components of yield were evaluated in Amelanchier denticulata
collections. Data analyses showed that fruit and seed production varied across years
and collections. There was a negative relationship between altitude and fruit size,
and there was positive relation between fruit size and average temperature 30 days
prior to harvesting. A negative relationship was found between seed weight and altitude as well as between soil pH and seed weight, whereas positive relationship
was found between maximum temperatures 30 days before harvest and seed
weight. The mean number of seeds per fruit ranged between 0.9 and 1.9.
Laboratory evaluations showed that a hard seed coat was absent in seeds of
all collections. The optimum seed germination temperature was at 20°C. Fresh
seeds were germinated at 20°C, which was the optimum germination temperature,
and data analyses were by using binomial logistic regression and a quasi-likelihood
model. Collections were grouped according to dormancy proportions: (a) < 0.10,
(b) between 0.10 and 0.25, and (c) > 0.50. The higher elevation collection had the
highest proportion of dormant seeds (0.62), germination was slow and highly
variable; lower elevation collections had a low proportion of dormant seeds (<
0.15), and germination was rapid. In fresh seed of the SuchixtlánlYanhuitlán
collection (2263 m altitude), dormant seed proportions reduced from 0.62 to 0.29
after 14 days of prechilling. In this collection, dormant seed proportions dropped
from 0.62 to 0.08 after storing fresh seeds four months at room temperature (2 1°C);
while, in the SuchixtlánlSinaxtla collection, reduction of dormant seeds was from
0.25 to 0.04 (2185 m altitude).
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