Photosynthesis and rhizome carbohydrate concentrations of switchgrass grown from reserve-depleted rhizomes

A long-standing question in perennial grass breeding and physiology is whether yield improvement strategies could compromise winter survival. Perennial grasses rely on the pool of carbohydrates accumulated in storage organs from the previous growing season for winter maintenance and spring regrowth. Yield improvement strategies could reduce winter survival if they increase biomass and grain yields at the expense of carbon allocation to storage. Therefore, it is crucial to better understand the dependence of regrowth on storage reserves. We experimentally depleted switchgrass (Panicum virgatum L.) rhizome reserves by storing rhizomes for two weeks at 5 °C (control treatment) and 25 °C (reserve-depleted treatment). During the storage period rhizome respiration was 5.3x higher at 25 °C (0.010 μmol CO2 g-1 min-1 at 5 °C vs. 0.054 μmolCO2 g-1 min-1 at 25 °C; P < 0.0001) and the starch content was depleted by 30% by the end of storage. Surprisingly, reserve-depleted switchgrass had 60 % la..., Rhizomes used in this experiment were harvested from a 12-year-old switchgrass stand in the Michigan State University Agronomy Farm (42.713 N, -84.467 W) in East Lansing, Michigan, USA. Rhizomes were harvested during winter, in early January, and stored at 5 °C for two weeks before the start of the reserve-depletion treatment. Reserve-depletion was imposed by storing switchgrass rhizomes at 25 °C for 14 days, control treatment rhizomes remained at 5 °C for the same period.
Immediately after the storage period, rhizomes were planted individually in 2.54 L pots filled with a peat and perlite mix (SureMixTM; Michigan Grower Products, Galesburg, MI, USA) and kept in a greenhouse at 27 °C and 16hr photoperiod supplemented with artificial lights for the length of the growth cycle (~180 days). Rhizome respiration, development, and photosynthesis were measured repeatedly over the course of the experiment. These non-destructive measurements were taken on randomly assigned rhizomes weekly or biwe..., We used R (R Core Team, 2017) for all analyses and plots. We used lm() to fit linear models, gnls() in the nlme package to fir nonlinear models (Pinherio & Bates, 2000), and emmeans() in the emmeans package (Lenth, Singmann, Love, Buerkner, & Herve, 2018) for mean and parameter comparisons.
Code for data analysis and plotting can be found at: https://github.com/PerennialDr/SinkDepletion , A 30% reduction in switchgrass rhizome reserves did not decrease biomass yield.
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Dataset compiles switchgrass (Panicum virgatum) carbohydrate (Glucose, sucrose and starch content in leaves and rhizome), development (tillering, leaf development flowering, and senescence), photosynthesis (net CO2 assimilation, stomatal conductance to water, and Photosystem II efficiency) and biomass data (Aboveground, root, rhizome biomass, leaf area) measured repeatedly over switchgrass growth cycle. Plants were grown from reserve-depleted and control rhizomes. Control and reserve-depleted rhizomes were stored at 5 C and 25 C, respectively, for 14 days. The aim of the study was to study the effects of switchgrass rhizome reserves on physiology and development.

## Description of the data and file structure

Data are presented in a long format. Each row corresponds to an observation of an individual plant (RhiID).
Repeated measurements were taken for development and photosynthesis, biomass data collec...