¿Deben los modelos de emergencia de Lolium rigidum adaptarse en función de las condiciones climáticas?

Lolium rigidum es una problemática mala hierba a nivel mundial que en España produce importantes pérdidas de cultivo y económicas. El grupo de Biología y Agroecología de Malas hierbas (BAMh) de la SEMh ha estudiado la emergencia de esta especie durante dos campañas, 2016-17 y 2017-18. Para ello, se estableció un experimento en 10 localidades con una población de L. rigidum recolectada en Cataluña y se realizó el seguimiento de su emergencia cada 2-7 días. La emergencia se parametrizó en función de registros de temperatura y humedad procedentes de un datalogger enterrado a 2 cm. Los resultados muestran que el uso de los grados térmicos horarios es suficiente para una correcta descripción de la emergencia, desechando la opción de aplicar los grados hidrotérmicos, más comunes en los modelos de malas hierbas de invierno. Sin embargo, la emergencia de esta población de L. rigidum fue diferente en el centro y noreste de España respecto al sur, sugiriendo un efecto ambiental debido a su adaptación climática. Por ello, se plantea la necesidad de incluir poblaciones locales con el fin de adaptar el modelo desarrollado en el presente trabajo para los biotipos climáticos existentesPostprint (published version

Pollen-Mediated Movement of Herbicide Resistance Genes in Lolium rigidum.

The transfer of herbicide resistance genes by pollen is a major concern in cross-pollinated species such as annual ryegrass (Lolium rigidum). A two-year study was conducted in the greenhouse, under favorable conditions for pollination, to generate information on potential maximum cross-pollination. This maximum cross-pollination rate was 56.1%. A three-year field trial was also conducted to study the cross-pollination rates in terms of distance and orientation to an herbicide-resistant pollen source. Under field conditions, cross-pollination rates varied from 5.5% to 11.6% in plants adjacent to the pollen source and decreased with increasing distances (1.5 to 8.9% at 15 m distance and up to 4.1% at 25 m in the downwind direction). Environmental conditions influenced the cross-pollination both under greenhouse and field conditions. Data were fit to an exponential decay model to predict gene flow at increasing distances. This model predicted an average gene flow of 7.1% when the pollen donor and recipient plants were at 0 m distance from each other. Pollen-mediated gene flow declined by 50% at 16.7 m from the pollen source, yet under downwind conditions gene flow of 5.2% was predicted at 25 m, the farthest distance studied. Knowledge of cross-pollination rates will be useful for assessing the spread of herbicide resistance genes in L. rigidum and in developing appropriate strategies for its mitigation

Evidence of natural hybridization between

This study deals with hybrids between Aegilops geniculata and bread wheat, Triticum aestivum L., detected in two Ae. geniculata populations in the “Meseta Central”, Spain’s central plateau where wheat is a major crop. Morphological traits and pentaploid chromosome numbers were used to identify hybrids in 2004 and 2005. The frequency of hybridization under natural conditions was calculated for one of these populations. Six hybrids were detected from a sample of 3158 seeds from this population. The hybrids were mainly sterile but seed set can be found. This study extends the range of documented hybridization to include central Spain. The potential risks associated with natural hybridization in the context of transgenic wheat cultivation are discussed

Natural hybridization between wheat (Triticum aestivum L.) and its wild relatives Aegilops geniculata Roth and Aegilops triuncialis L

8 Pág.Cultivated bread wheat (Triticum aestivum L.) spontaneously hybridizes with wild/weedy related Aegilops populations, but little is known about the actual rates at which this hybridization occurs under field conditions. It is very important to provide reliable empirical data on this phenomenon in order to assess the potential crop-wild introgression, especially in the context of conducting risk assessments for the commercialization of genetically modified (GM) wheat, as gene flow from wheat to Aegilops species could transfer into the wild species genes coding for traits such as resistance to herbicides, insects, diseases or environmental stresses.This work was supported by the Comisión Interministerial de Ciencia y Tecnología (CICYT) from Spain under the project AGL2004-07101-C02-01/AGRPeer reviewe

Estimated regression curves for the pollen-mediated gene flow in <i>L</i>. <i>rigidum</i> as a function of the distance.

<p>A) Regression curves for each growing season, B) Regression curves conducted with the pooled data for all growing seasons and for the worst-case scenario, with data set obtained from the downwind direction (Dw) in 2011 in which the pollen mediated gene flow was the highest.</p