Heterogeneity in short-term allocation of carbon to roots of Pinus tabuliformis seedlings and root respiration under drought stress

• DOI: 10.1007/s11104-020-04562-9
• Publication Date: 2020-05-30T07:02:36Z
• Authors: Ying Liu; Peng Li; Lie Xiao; Wen Wang; Kunxia Yu; Peng Shi
• Keywords: 0106 biological sciences; 2. Zero hunger; 15. Life on land; 01 natural sciences; 6. Clean water

The purpose of this study was to investigate the drought response mechanisms that underlie carbon allocation and carbon demand in roots. The correlations between root traits and the amount of carbon (C) allocated to different orders of roots were tested using 13C pulse labeling. The amount of 13C was measured by quantifying the CO2 emitted from respiring roots of Pinus tabuliformis excised 0, 1, 3, 9, 21, 81 and 120 days after labeling. 1) Moderate drought stress significantly increased the root to shoot biomass ratio, the biomass ratio of the first three orders to the 4th- and 5th-order roots, and the cumulative root length and root area of the 1st-order roots. 2) 120 days after labeling, 13C amount allocated to 1st- and 2nd-order roots was significantly higher in all drought stress treatments than adequate water supply treatment, with the exception of 13C in 1st-order roots undergoing the severe drought stress treatment. Root respiration was significantly and positively correlated with 13C in the 1st- and 2nd-order roots in all drought stress treatments. 3) The 13C ratios of all the droughted treatments vs water supply treatment were significantly higher in the 1st- and 2nd-order roots than in the 4th- and 5th-order roots, with the exception of the 1st-order roots in the most severe drought treatment. Drought stress elevated C demand in lower-order roots by increasing the lower-order root respiration rate and by expanding the photosynthate allocation to the fine roots to enhance their structural growth.