Effects of nitrogen and vapour pressure deficit on phytomer growth and development in a C4 grass

Abstract

The morphology of almost all grasses can be conceptualized as a hierarchical arrangement of subunits, termed phytomers. Therefore, knowledge of phytomer growth and development serves as a basis to elucidate the rhythm of grass growth. This study provides systematic analyses on the process of phytomer development of C. squarrosa, a perennial C4 grass. The invariant coordination of elongation within and between phytomers was a stable developmental feature across treatments, thus the quantitative coordination rules are applicable for predicting morphological development of C. squarrosa under contrasting levels of nitrogen nutrition or vapour pressure deficit.

An oxygen isotope chronometer for cellulose deposition: the successive leaves formed by tillers of a C4 perennial grass

“…). For every category (1 to n ), the stage of blade development and growth (as a fraction of final blade length, f FBL ) at the times of transfer and harvest was estimated from knowledge of the leaf appearance interval, development of individual phytomers, and the contribution of the leaf blade component to phytomer development in the same study (Yang et al ). Figure illustrates the time course of leaf blade elongation, as calculated from phytomer elongation and the fractional contribution of the leaf blades to phytomer elongation for the constant low‐VPD and high‐VPD treatments in plants grown at ‘low N’ (cf.…”

“…figs 3a and 5 by Yang et al . ), the ‘control’ treatments presented here. The tip of a leaf emerged from the enclosing sheath of the next older leaf when the blade had reached 31% of its final length.…”

“…; Yang et al . ) may provide another model for the study of the temporal dynamics and integration of 18 O‐signal deposition in cellulose, as individual leaves consitute clearly and easily identifiable morphological units whose development can be monitored easily. That model has not been studied in any detail so far.…”

“…The C 4 grasses may be particularly suitable for dynamic isotopic time series analyses, as they exhibit short and predictable leaf appearance intervals (phyllochrons) and have several leaves at different developmental stages of the leaf growth process during vegetative development (Yang et al ). Therefore, and as growth substrate pools for leaf growth have a high turnover (Lattanzi et al ), one should expect a high‐temporal resolution of the cellulose – 18 O record of the successively formed leaves in C 4 grasses.…”

“…), as in other C 3 and C 4 grasses (Helliker & Ehleringer ). In the same experiment, we performed a detailed analysis of the development of successive phytomers, and of their blade, sheath and internode parts, for plants grown in contrasting VPDs (Yang et al ). Plants were grown at high and low VPD, and some of them swapped between VPD environments and exposed to the new environment for 7 d while simultaneously labelling the photosynthetically fixed carbon with 13 CO 2 / 12 CO 2 mixtures of known constant isotopic composition at near‐ambient CO 2 concentration.…”