CHANGES IN SOLUBLE SOLID CONTENT IN GREEN ASPARAGUS SPEARS DURING HARVEST SEASON

The aim of research was to evaluate changes in soluble solid content in green asparagus (Asparagus officinalis) spears and the effect of different factors on it. A field experiment was carried out on two asparagus cultivars 'Gijnlim' and 'Backlim' in the years 2002 – 2004. The end of the harvest period was varied according to the five following treatments: June 20 (control), June 10, June 30, 50 days after the beginning of harvest, and when the sum of average daily temperatures equaled 750°C˙d. During the harvest period soluble solid content was determined every 7 to 10 days by means of a refractometer. The soluble solid content meant substances, which refract light e.g. carbohydrates, organic acids and pigments. The content ranged from 3.0% to 8.5%. From the beginning to the end of the harvest period it was decreasing but it fluctuated markedly depending on the weather conditions, e.g. the combination of high temperature and rainfall shortage for a few days before measurement resulted in a significant increase of soluble solid content. The soluble solid content also depended on the size of spears with lower values in spears of smaller weight. In optimum length of harvest period mean soluble solid content was the highest.