La VBG como una Violación de los Derechos Así pues, la violencia basada en el género es una problemática que representa una de las principales

As germination is a function of hydrothermal time (Bradford, 1995) we would expect it to change with water input. We would also expect increasing organic matter to improve the water retention capacity of the soil and so too to lead to an increased rate of germination. However, the results were somewhat contrary to this expectation. We did observe higher levels of germination when water input was high, yet the medium organic matter soil allowed more seeds to germinate than the high organic matter soil. We speculate this may be due to mulching from the compost used to elevate the soil

chemistry of the soil affecting water uptake. These impacts of environmental properties on germination could have an impact in terms of management practices as delayed drilling is a common method of cultural control. However, if the timing of germination can be affected by environmental processes then perhaps this needs to be taken into consideration when developing management programs.

As plant height was affected by various soil properties this too could have important implications for management practices as the taller a plant is at maturity, the greater the opportunity for seed dispersal over longer distances meaning patches may expand in the following season (Howardet al., 1991). However, this needs to be interpreted in the context of the trade-off between fewer, taller tillers and a greater number of shorter tillers with greater seed production.

The competitive balance between wheat andA. myosuroideswas affected by soil pH withA. myosuroideshaving a greater relative growth at lower pH. This indicates that soil pH may have some influence on the location ofA. myosuroidespatches. It is likely this effect is related to the availability of nutrients at varying soil pH; for example, nitrogen, phosphorus, and potassium are all limited in availability in acid soil, whilst iron, zinc, and copper become limited in more alkaline soil (Brady, 1984). The contrasting rooting structure and function ofA. myosuroidesand wheat have been suggested as a possible reason for the current distribution of A. myosuroides in relation to variation in soil properties (Stratonovitchet al., 2012).

When we compare these results to field observations obtained in a previous study (Metcalfeet al., 2016, Chapter 2) they support the conclusion that pH may have some controlling influence over the within-field distribution ofA. myosuroides. In the field, we found higher densities ofA. myosuroidesat lower pH. If, as indicated here, more A. myosuroidesseeds germinate on acidic soil and it is better able to compete with wheat then this could explain the higher densities ofA. myosuroidesobserved on more acidic soil.

Some of the responses to increased organic matter observed here may not have been due to the changes in soil function, but rather due to the increased fertility owing to the compost addition. On farm, an increase in soil organic matter could also lead to increased fertility and so it is not always possible to separate these effects. However, if a farmer is selectively applying fertiliser to parts of the field to account for this then

it may be necessary to investigate the effects of organic matter further, independently of soil fertility, through the addition of inorganic nutrients to the low organic matter treatments. This would then allow the study of changing soil function with organic matter and its effects on the life-cycle of the weed, independently from the effects of increased fertility.

These results raise some interesting questions in terms of management of A. myosuroidesand whether management options should be tailored to within-field environmental gradients. We have presented evidence that high organic matter soil is favourable toA. myosuroidesseed production, but perhaps less so for germination. We have also found further evidence that there is a subtle difference in the optimum pH for wheat andA. myosuroides. Combining our experience in field and pot experiments, we suggest soil above a pH of 6, is less favourable toA. myosuroidesbut still optimal for wheat. However further research would be needed to understand how the system responds to a wider range of soil organic matter contents, watering, and pH.

These results indicate a potential trade-off between increasing organic matter in the soil for crop growth and reducing it forA. myosuroides control as the number of seed heads can be significantly reduced by lowering soil organic matter. This raises questions about the suitability of popular management techniques such as minimum tillage in a high A. myosuroidessituation. Potential management options for further exploration could be the use of liming where pH is particularly low as part of a suite of measures (including improving soil structure and drainage) designed to manipulate habitat suitability forA. myosuroides. The use of competitive crop cultivars could also be investigated to determine if cultivars can remain competitive on low soil pH or high organic matter and so would be better able to suppressA. myosuroidesgrowth under these conditions.