Premium
Atmospheric CO 2 and VPD alter the diel oscillation of leaf elongation in perennial ryegrass: compensation of hydraulic limitation by stored‐growth
Author(s) -
Baca Cabrera Juan C.,
Hirl Regina T.,
Zhu Jianjun,
Schäufele Rudi,
Schnyder Hans
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16639
Subject(s) - turgor pressure , transpiration , vapour pressure deficit , diel vertical migration , perennial plant , elongation , stomatal conductance , horticulture , morning , osmotic pressure , diurnal temperature variation , botany , biology , chemistry , agronomy , photosynthesis , atmospheric sciences , ecology , materials science , ultimate tensile strength , metallurgy , geology
Summary We explored the effects of atmospheric CO 2 concentration ( C a ) and vapor pressure deficit (VPD) on putative mechanisms controlling leaf elongation in perennial ryegrass. Plants were grown in stands at a C a of 200, 400 or 800 μmol mol −1 combined with high (1.17 kPa) or low (0.59 kPa) VPD during the 16 h‐day in well‐watered conditions with reduced nitrogen supply. We measured day : night‐variation of leaf elongation rate (LER day : LER night ), final leaf length and width, epidermal cell number and length, stomatal conductance, transpiration, leaf water potential and water‐soluble carbohydrates and osmotic potential in the leaf growth‐and‐differentiation zone (LGDZ). Daily mean LER or morphometric parameters did not differ between treatments, but LER night strongly exceeded LER day , particularly at low C a and high VPD. Across treatments LER day was negatively related to transpiration ( R 2 = 0.75) and leaf water potential ( R 2 = 0.81), while LER night was independent of leaf water potential or turgor. Enhancement of LER night over LER day was proportional to the turgor‐change between day and night ( R 2 = 0.93). LGDZ sugar concentration was high throughout diel cycles, providing no evidence of source limitation in any treatment. Our data indicate a mechanism of diel cycling between daytime hydraulic and night‐time stored‐growth controls of LER, buffering C a and daytime VPD effects on leaf elongation.