Dry Matter Partitioning and Vegetative Growth of Young Peach Trees Under Water Stress

Abstract

Water stress affected the growth and dry matter partitioning of young peach trees grown in pots in a greenhouse. When the trees were subjected to four watering treatments, 100, 75, 50 and 25% of full water, total dry matter production was reduced with each incremental decrease in applied water. Despite large differences in biomass production, the difference in midday leaf water potential between the wettest and driest treatment was not greater than 0.6 MPa. This was partially attributed to lower leaf conductance in the drier treatments.

A reduction or halting of lateral branching and new leaf production was observed soon after water stress was imposed, and these two factors were the major contributors to differences in tree biomass production. Root production was maintained at similar levels in all but the severest stress treatment. As a result, the root fraction of total biomass increased from 0.4 to 0.6 as the level of stress increased from 75 to 50% of full water.

Currently growing leaves and internodes of the drier treatments reached maturity at a smaller size. In contrast to internode lengthening, leaf area expansion slowed in the final growth phase. This correlated well with leaf unfolding.