Seasonality of Growth in Grass-Clover Swards Under Repetitive Nitrogen Application

The cohabitation of grass and clover is possibly due to asynchrony in their growth patterns, and to the beneficial effects of fixed nitrogen (N) on grass. Incompatibility of clover persistence with N fertilisation has been frequently reported (Nassiri and Elgersma, 2002). However, limited information is available regarding the effect of repetitive application of N in mixed swards. This research aims to study the balance between species in response to application of increasing rates of N throughout the growing season

Modelling the Effect of a Variable Light Extinction Coefficient and Leaf Dispersion on Light Partitioning Between Species in a Grass-Clover Mixture

Light partitioning in a grass-clover mixture was studied using a general competition model. The model assumes a fixed extinction coefficient (k) and no leaf dispersion. This was compared with modelling the effect of different k of both species over height as well as the effect of type of leaf dispersion. These new assumptions led to a better estimation of the light partitioning between both species. For grass the effect of variable k and leaf dispersion was similar and in both cases the total absorbed light was lower than under default conditions. For clover the new assumptions led to a higher absorbed radiation than in the original model. However, in this case the effect of leaf dispersion was more important

Comparison of methods for determining the fatty acid composition of photosynthetic tissues

The fatty acid (FA) composition of photosynthetic tissue differs from that in other plant or animal tissues. In leaves, the lipid fraction constitutes less than 10% of the dry weight and is mostly located in the chloroplasts. An extraction solvent should dissolve polar lipids readily, but should also overcome interactions between the lipids and the tissue matrix. A mixture of chloroform/methanol (C/M) is commonly used. However, less toxic alternative methods such as hexane/isopropanol (H/I) and ethanol (E) have been suggested. In this preliminary study we compared the effectiveness of these three methods which are used as standard extraction protocols for FA analysis of plant material at three different European Universities. C/M extraction gave the highest total FA content and H/I the lowest, suggesting that C/M is indeed the best general-purpose lipid extraction solvent. Significant differences were also observed for FA composition including the ratio of saturated to unsaturated FA indicating selectivity of the various solvents in extracting different individual FA. Further and more detailed investigations are required to confirm this hypothesi

Fibre Degradation Rate of Perennial Ryegrass Varieties Measured Using Three Techniques: \u3cem\u3eIn Situ\u3c/em\u3e Nylon Bag, \u3cem\u3ein Vivo\u3c/em\u3e Rumen Evacuation and \u3cem\u3ein Vitro\u3c/em\u3e Gas Production

In Western Europe, perennial ryegrass is the most widely used grass species for grazing cattle, because of its high productivity, palatability and nutritive value. However, the low dry matter intake (DMI) of perennial ryegrass pasture has been identified as a major factor limiting milk production of high producing dairy cows. Altering the chemical, physical and mechanical characteristics that contribute to its low DMI through grass breeding and the choice of variety may be a way forward in trying to maximise its DMI. This study aimed to examine whether perennial ryegrass varieties differ in their NDF degradation rates (kdNDF)

Faculty and student perceptions of the feasibility of individual student–faculty meetings

The extent to which students feel involved in their education positively influences academic achievement. Individual student–faculty meetings can foster student involvement. To be effective, faculty acknowledgement of the benefit of these meetings is a prerequisite. The aim of this study was to explore faculty perceptions of individual student–faculty meetings. In addition we investigated students’ perceptions. As part of the undergraduate programme, mandatory individual intake and follow-up meetings between first-year medical students (n = 425) and senior faculty members (n = 34) have been implemented from 2009 onwards. We administered a questionnaire on faculty perceptions of the benefit and impact of intake meetings. Subsequently, after both meetings had been held, strong and weak points of the mandatory programme were explored using open-ended questions. Students’ perceptions were investigated by open-ended questions as a part of the curriculum evaluation process. Faculty enjoyed the meetings (90 %), perceived the meetings to be beneficial (74 %) and expected a positive effect on student involvement (74 %). Faculty appreciated the opportunity to give advice tailored to students’ personal needs and levels of performance. The students appreciated the meetings and the attention given to their personal situation and study progress. Faculty and student appreciation of the meetings seems to support the assumption that the individual meetings increase students’ social and academic involvement. Further research should focus on the impact of individual student–faculty meetings on students’ learning behaviours