Effects of Water Stress on Fruit Growth and the Partitioning of 13C-Assimilates in 'Nijisseiki' Pear Trees.

Abstract

Two soil water status conditions (control : pF=1.5-1.7 and water stress : pF=2.7-2.8) were applied to 5-year-old, potted 'Nijisseiki' pear trees during early stage (43-62 days after anthesis (DAA)) and late stage of fruit growth (110-124 DAA). Water stress during the early stage or late stage of fruit growth decreased photosynthetic rate and leaf water potential ; reduced fruit size and fresh weight but had no effect on the dry weight of fruit. Shoot growth was significantly reduced by water stress during the early stage of fruit growth. Water stress reduced the amount of 13C translocated to young leaves and current shoots during the early stage of fruit growth, but did not significantly affect rate of 13C translocated into fruit in both stages. Water stress at both stages increased the incorporation of 13C into soluble carbohydrates in fruit ; similar conditions occurred with mature leaves and current shoots early in the season.