No abstract

The purpose of this research was to study the effect of vernalization on flowering time in thirty accessions of Triticum turgidum spp. durum. To this end, screening of allelic variation at VRN‐1 loci was carried out using PCR‐based markers and DNA sequencing, and gene expression analysis was performed in two and four developmental stages, with and without cold treatment. In non‐vernalized plants, average days to flowering ranged from 34 to 99 days and only one accession was observed to remain at the vegetative stage. Three accessions were found to accelerate flowering after cold treatment. At VRN‐A1 locus, three alleles previously characterized, Vrn‐A1b, Vrn‐A1c and vrn‐A1, were detected. No polymorphisms at VRN‐B1 locus were observed. The differences in vernalization response among the genotypes studied could be explained by allelic variation and VRN‐A1 transcript levels. Variability in flowering time and sensitivity to vernalization in a collection of durum wheat, both potentially useful to the development of new varieties, were observed. This information is key to directing breeding cultivars for adaptation.

No abstract

O. González, G. Pérez Camargo, M. Membiela, D. Frezza, N. Bartoloni, and C. Vieites. 2009. Discrete observations of the Helix aspersa land snails' spatial distribution in an outdoor system. Cien. Inv. Agr. 36(1):123-130. In this study, adult Helix apersa land snails with previously established periodicity were observed at three densities in their fi nishing stage in order to contribute to the body of knowledge about spatial distribution and certain behavior patterns in an outdoor system. From November 8 to December 18, 2006, snails that were in their fi nal fattening phase were grouped at three densities (50 snailּm-², 100 snailּm-², 200 snailּm-²) and randomly placed in nine cubicles, with three replicates of each density. Twelve observations of the snail behavior were made between 12 am and 1 pm. The categories selected as "discrete acts" include: observing the snails in the shelters, on Swiss chard leaves (Beta vulgaris), adhered to the netting, on the balanced feed, on the water supply tray, and on the ground. A statistical analysis employing marginal and partial frequency tests was completed on the density x category x time interactions. It was concluded that around midday, the majority of the snails remained in the artifi cial shelters and on the Swiss chard monoculture leaves. In addition, differences were not detected for the rest of the categories in regard to the spatial distribution of the individuals in the three densities analyzed. If lower densities than the ones most commonly employed in studies (200 snailּm-²) are used in an open outdoor system in the fattening stage, the individuals will use the available space in a similar way, thereby exhibiting similar behavior patterns.

O.M. González, G. Pérez Camargo, M. Membiela, D. Frezza, N. Bartoloni, and C. Vieites. 2008. Effect of population density on snail productivity (Helix aspersa) in an open sky system fed with Swiss chard and a balanced food supplement. Cien. Inv. Agr. 35(3):251-257. Heliciculture is performed worldwide and has been promoted in Argentina; however, its development and expansion has been limited by several factors that make it impossible to reach the production volumes necessary for a commercial scale. Among other factors, it has been impossible to obtain a high amount of fi nished product according to the initial density determined in the fattening stage; additionally, diffi culty in maintaining an adequate forage supply has limited snail production. In this study, the infl uence of snail density using balanced food supply on the fi nal production was studied in an open sky system. Density had no signifi cant effect on the mean fi nal live weight. For snails cultured at densities higher than 200 snail•m-2 , the average diameter was lower than for snails cultured at 50 snail•m-2 (low density); however, the difference between the moderate snail density (100 snail•m-2) and the low density was not signifi cant. The highest productivity per unit of surface was about 510 g•m 2 (n = 200), which is similar to the amount that heliciculture producers want to achieve and slightly lower than what has been reported previously.