2.4. Quality measurements
All apples from experimental inflorescences were collected one day to a week before commercial harvest at each of the orchards (early September for Cox, mid September for Gala). Apples were bagged individually by treatment, tree, row and orchard and taken back to the laboratory for quality assessment. Within 5 days of harvest, quality measures had been taken from 531 apples and seeds had been counted in 735 apples.
Quality measures included; fresh weight, taken on a Mettler Toledo balance sensitive to the nearest 0.1 g; maximum width, measured using callipers sensitive to 0.1 mm; firmness in kg/cm, taken using a Silverline penetrometer and percentage sugar concentration or Brix, using a Hanna refractometer. Apples were also scored for shape, either classified as ‘normal’, or ‘deformed’ if there was any shape irregularity. Size, shape, sugar content and firmness are all measures used by the apple processing industry to understand the quality of apples produced. Larger apples with an even shape are preferred and high sugar content and firmness is considered desirable and gives improved taste. Additional data on the seed number per apple was taken from apples removed at harvest and on the visit made to orchards for apple thinning. In order for the economic value of pollination to apple production to be calculated, apples were classed using parameters utilised in the industry (Jenner, 2013, pers. comm.). Apples were classified as class 1 or 2 based on size and shape. Class 1 apples are those with no shape deformities and a maximum width greater than 60 mm, all other apples were class 2.
The mineral content of apples can have marked effects on quality parameters such as storability and resistance to disease (Conway et al., 2002). Given the clear effects of insect pollination on Gala quality, for a sub set of the Gala apples, mineral analysis was carried out. Apples from those trees with at least one open pollinated, hand pollinated and pollinator-excluded apple set were sent for mg/100 g measurements of calcium, phosphorus, nitrogen, potassium, magnesium, boron and zinc. This means 87 apples from 29 trees were involved in mineral analysis.
2.5. Economic valuation
Market value of apple production per hectare depends on several factors, some of which are directly influenced by pollination services; higher fruit set and greater weight result in greater overall output and quality parameters