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Reproductive phenology and pre-dispersal fruit predation in Atriplex halimus L. ( Chenopodiaceae )

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ABSTRACT

Background: The flowering phenology pattern of Atriplex halimus was studied in a Mediterranean habitat in order to analyze protandry effectiveness. Fruit set evolution was recorded over two years and the impact of pre-dispersal predation by insects was also evaluated.

Results: The flowering phenology coincided in 2006 and 2007, starting in mid-July and reaching full flowering at the end of August in both years. Inflorescences are composed of glomerules with 8.78 ± 2.79 male flowers and 4.57 ± 2.58 female flowers, with no significant differences in position on the inflorescence. The peaks of male and female flower anthesis were reached in mid-August, but the male maximum occurred one week before the female. Plants at the start of flowering only bear male flowers, but female flowers soon appear. Fruit set starts at the end of August; all the flowers were transformed into fruit by mid-September and their development continued to the beginning of October, when fruit structures had matured and began to drop. Fruit predation started at the end of September and reached maximum intensity in mid-October.

Conclusions: At population level, male and female flowers seemed to open in the same weeks, but at plant and glomerule level male flowers opened one week before the females. Fruit predation levels were 62.42 and 43.14% in 2006 and 2007 respectively, with no significant differences between different parts of the inflorescence. And larvae of Coleophoridae were the most abundant predators.

Electronic supplementary material: The online version of this article (doi:10.1186/1999-3110-54-4) contains supplementary material, which is available to authorized users.

No MeSH data available.


Weekly total and predated fruits per glomerule and predation level.
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Fig7: Weekly total and predated fruits per glomerule and predation level.

Mentions: Maximum values of fruit per glomerule were recorded on 28 August 2006 and 18 September 2007 (Figure 7). The global mean number of fruits per glomerule on these dates, including the weeks before and after the peak, was 4.57 ± 2.58 (2006) and 3.19 ± 1.32 (2007), the differences being significant (Kruskal-Wallis: H = 18.51, p < 0.001). The glomerules from the upper, middle and lower levels in 2006 contained 4.07 ± 1.89, 4.87 ± 3.26 and 4.77 ± 2.42 fruits respectively, with no significant differences between the three (Kruskal-Wallis: H = 0.97, p = 0.61). In 2007 these values were 3.40 ± 1.43, 3.10 ± 1.09 and 3.07 ± 1.44 fruits, once again with no significant differences between them (Kruskal-Wallis H = 1.08; p = 0.58). From these peaks the number of fruits per glomerule decreased as a consequence of fruit structure separation from the glomerule. This liberation was faster in 2006 than in 2007.Figure 7


Reproductive phenology and pre-dispersal fruit predation in Atriplex halimus L. ( Chenopodiaceae )
Weekly total and predated fruits per glomerule and predation level.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5383916&req=5

Fig7: Weekly total and predated fruits per glomerule and predation level.
Mentions: Maximum values of fruit per glomerule were recorded on 28 August 2006 and 18 September 2007 (Figure 7). The global mean number of fruits per glomerule on these dates, including the weeks before and after the peak, was 4.57 ± 2.58 (2006) and 3.19 ± 1.32 (2007), the differences being significant (Kruskal-Wallis: H = 18.51, p < 0.001). The glomerules from the upper, middle and lower levels in 2006 contained 4.07 ± 1.89, 4.87 ± 3.26 and 4.77 ± 2.42 fruits respectively, with no significant differences between the three (Kruskal-Wallis: H = 0.97, p = 0.61). In 2007 these values were 3.40 ± 1.43, 3.10 ± 1.09 and 3.07 ± 1.44 fruits, once again with no significant differences between them (Kruskal-Wallis H = 1.08; p = 0.58). From these peaks the number of fruits per glomerule decreased as a consequence of fruit structure separation from the glomerule. This liberation was faster in 2006 than in 2007.Figure 7

View Article: PubMed Central

ABSTRACT

Background: The flowering phenology pattern of Atriplex halimus was studied in a Mediterranean habitat in order to analyze protandry effectiveness. Fruit set evolution was recorded over two years and the impact of pre-dispersal predation by insects was also evaluated.

Results: The flowering phenology coincided in 2006 and 2007, starting in mid-July and reaching full flowering at the end of August in both years. Inflorescences are composed of glomerules with 8.78&thinsp;&plusmn;&thinsp;2.79 male flowers and 4.57&thinsp;&plusmn;&thinsp;2.58 female flowers, with no significant differences in position on the inflorescence. The peaks of male and female flower anthesis were reached in mid-August, but the male maximum occurred one week before the female. Plants at the start of flowering only bear male flowers, but female flowers soon appear. Fruit set starts at the end of August; all the flowers were transformed into fruit by mid-September and their development continued to the beginning of October, when fruit structures had matured and began to drop. Fruit predation started at the end of September and reached maximum intensity in mid-October.

Conclusions: At population level, male and female flowers seemed to open in the same weeks, but at plant and glomerule level male flowers opened one week before the females. Fruit predation levels were 62.42 and 43.14% in 2006 and 2007 respectively, with no significant differences between different parts of the inflorescence. And larvae of Coleophoridae were the most abundant predators.

Electronic supplementary material: The online version of this article (doi:10.1186/1999-3110-54-4) contains supplementary material, which is available to authorized users.

No MeSH data available.