Analyzing water uptake of apple trees using isotopic techniques in the Shandong Peninsula, China

Abstract

Study region

The hilly area of Shandong Peninsula is a pivotal apple-producing region in China. However, the precise water sources utilized by the apple trees for transpiration remain poorly understood in this region.

Study focus

Here we quantify the water sources used by apple trees in this area using stable isotopic tracing methods. Through on-field studies in a representative apple orchard and subsequent isotopic assessments, the primary water sources tapped by the apple trees were identified in three plots with contrasting soil characteristics and through 5 days of sub daily sampling.

New hydrological insights for the region

Our results show that apple trees have a marked preference for soil water centered at the 60 cm depth, with more deep water use at plots without weathered layers. Notably, the isotopic compositions of the xylem water leaned more towards signatures of soil water, rather than immediate irrigation water or groundwater. Given the irrigation water used to be the dominant water source recharging into soil, the weak contribution of irrigation water to plant would be attributed to the high soil evaporation rates during the growth phase, which strongly alter the isotopic composition of irrigation water in shallow soil layers. These insights boosted our comprehension of water sourcing mechanisms in the sloped orchard ecosystems in the Shandong Peninsula and lay the groundwork for deeper exploration into the irrigation ratio to rainwater utilized by apple trees in comparable regions.