The record of daily average grass pollen concentrations monitored at St Mary's Hospital, Paddington, London, U.K. since 1961 is the longest duration pollen data set in Europe. Analysis of the results identifies the trends and characteristics of grass pollen seasons over three decades. During this time seasonal allergic rhinitis has increased significantly in Britain. The annual start dates, length of season and severity are examined in relation to the main meteorological variables of cumulated temperatures above 5.5 degrees C and precipitation measured at one site within London and two in the surrounding rural areas. Land-use changes are also considered. Significant decreases have taken place in both the duration and severity of the seasons, particularly between the 1960s and the early 1970s but also through the last 20 yr. This is largely a result of a decrease in pollen abundance in the region. The decline in pollen counts has slowed in recent years due to the increase in flowering grasses caused by the set-aside policy and by uncut verges. Grass pollen seasons have tended to start later over the last two decades, despite an increase in the cumulated temperature profiles during late winter and spring. Empirical models have been developed using multiple regressions to incorporate meteorological and pollen data for the last 20 yr in order to forecast the start dates, duration and severity of the grass pollen seasons. These models were applied successfully using the data for 1991 and 1992. Predictions of the main characteristics of the pollen seasons can be obtained relatively early in the year through the use of these models by employing the monthly weather forecasts in conjunction with long-term average weather profiles.

The contrasting patterns both in the pollen records and land-use changes between the three sites emphasize the need for regional data. The predictive models achieved a high degree of explanation enabling pollen season severity to be forecast with high confidence shortly before the start date.

No abstract

(1994) Variation in the start of the grass pollen season at selected sites in the united kingdom 1987-1992

Strategies to improve marketability of small fruits include the identification of characteristics that contribute to longer shelf life. One characteristic of a durable berry is that it retains moisture after harvest and resists desiccation. In our study of 10 thornless blackberry cultivars and selections during refrigerated storage, weight loss varied from 1% to 3% per day and rates were linear for 10 days. Fluid leakage was not a factor, and the primary source of weight loss was concluded to be transpiration. Microscopy was performed to identify structural correlates of berry weight loss. Surface wax on plant structures is known to be a barrier to water loss.Representative berries from the hand-selected fruits, sorted for weight loss analysis, were processed for microscopy 24-36 hr after harvest, during which time the fruits were held at 0-1 C. Samples were fixed with glutaraldehyde and osmium tetroxide, dehydrated with an acetone series, and embedded in Spurr's resin.