Influence of water regimes and mineral contents in soil upon the contents of minerals, sugars and organic acids in pear fruits (Pyrus communis L.) Cv. 'Williams'

In the years 1997 and 1998 we studied the influence of early and late water stresses, the influence of mineral contents in the soil and their conseque nces on the contents of sugars (glucose, fructose and sucrose), sorbitol an d organic acids (malic, citric, fumaric and shikimic) in the pear fruits of cv. 'Williams'. The contents of sugars and organic acids were determined b y HPLC analysis. The experiment encompassed three observations: early water stress (from June the 1(st) to July the 15(th)), late water stress (from J uly the 15(th) until picking time) and control. The soil was optimally supp lied by minerals, there was only a bit more of Ca, Mg and Cu. We stated tha t troubled water supply in the treatment with late water stress caused smal ler admissions of Ca, K and B and higher contents of soluble solids in the fruits, early water stress on the other hand influenced the lower contents of Ca and sucrose in the fruits. Troubled water supply at the beginning and at the end of fruit development (early and late water stresses) influenced a higher content of N in the fruits in the year 1997. In the treatment wit h early water stress we stated higher contents of K and citric acid than in the control in the year 1997.