Decoupled drought responses of fine-root versus leaf acquisitive traits among six Prunus hybrids

• Published in: Journal of plant ecology Vol. 13; no. 3; pp. 304 - 312
• Main Authors: Zhou, Shuang-Xi, Walker, Rob R, Edwards, Everard
• Format: Journal Article
• Language: English
• Published: UK Oxford University Press 01-06-2020
• Subjects: Analysis; Australia; Droughts; Hybridization, Vegetable; Identification and classification; Prunus; Roots (Botany); Soil moisture; Australia; 比根表面积; specific root surface area; 多维度干旱响应; specific leaf area; 土壤水分胁迫; specific root length; 比根长; soil water stress; 比叶面积; multi-dimensional drought response
• ISSN: 1752-993X; 1752-9921; 1752-993X
• DOI: 10.1093/jpe/rtaa015

Abstract
Aims
Predicting drought consequences on forests and fruit crop plantings requires improved understanding of drought responses of both leaf and fine-root resource acquisitive traits (specific leaf area—SLA, specific root surface area—SRA and specific root length—SRL). We hypothesize their responses are coordinated towards integrated plant resource conservation under severe drought.
Methods
We tested the hypothesis with a greenhouse-based drought experiment on saplings of six Prunus hybrids with a priori known contrasting drought sensitivity. Saplings were subjected to either control (100% field capacity) or severe drought stress treatment (33% evapotranspiration of hybrid-specific control plants). Sample collections were carried out at 30 and at 60 days after the start of treatments, for both control and stressed saplings.
Important Findings
No hybrid showed concurrent significant decrease of SLA and SRA (or SRL) under severe drought. The fine-root traits of the six hybrids showed two major drought-response scenarios, in particular: (i) increased root tissue density (RTD) and decreased average root diameter without significant change of SRL and (ii) increased RTD and decreased SRL without significant change of average root diameter. Drought responses of leaf gas exchange, SRA, SRL and RTD were closely correlated along a gradient towards resource conservation from control to drought-stressed plants in all hybrids, which was orthogonal to another gradient characterized by a hybrid-dependent decrease of SLA. These findings highlight (i) the multi-dimensionality of root-trait drought responses, (ii) the decoupling between leaf economics and leaf hydraulics and (iii) the covariation of leaf and root hydraulics in terms of trait drought responses. The study contributes to identifying the origin of the multi-dimensionality of root-trait drought response at intraspecific scale, and highlights differential drought–response combinations of leaf and fine-root traits among hybrids to survive under severe soil drought stress.