The effects of spring versus summer heat events on two arid zone plant species under field conditions
Description
This dataset contains raw data for Milner, K.V., French, K., Krix, D.W., Valenzuela, S.M., and Leigh. A. (2023) The effects of spring versus summer heat events on two arid zone plant species under field conditions. Plant Functional Biology. We addressed the following questions: 1) Is a spring or summer heat stress event more detrimental to growth and fitness outcomes for desert plants? 2) How does nutrient availability influence downstream effects of heat stress? To address these questions we applied spring or summer heat stress to two Australian arid zone Solanum species grown under two nutrient treatments and followed plants through to fruiting. Briefly, plants exposed to a summer heat stress event faired more poorly than plants exposed to spring heat stress, however outcomes for reproductive fitness were species specific. This experiment used a fixed, four-factor design, each factor with two levels. The heat stress event was the level of replication; therefore the sample size was four (except where specified). Visible damage and survival were analysed using binomial logistic regression. ANOVA with Type II sums of squares using ‘lm’ function was applied to all other variables (leaf temperature, damage to PSII, membrane stability, LMA, growth rate, flower and fruit number, stem to leaf, flower or fruit to aboveground biomass ratios, leaf protein). Transformations were made where required to meet assumptions of analyses. Models were simplified by removal of non-significant interactions using and AIC values using ‘drop1’ function of ‘car’ package. Where there were significant interactions, Tukey HSD in ‘emmeans’ package was applied. For more information see Milner et al. (2023) and steps to reproduce.
Files
Steps to reproduce
Excel was used for data management and R for analysis. This experiment used a fixed, four-factor design, each factor with two levels. The heat stress event was the level of replication; therefore the sample size was four (except where specified). Visible damage and survival were analysed using binomial logistic regression. ANOVA with Type II sums of squares using ‘lm’ function was applied to all other variables (see Milner et al. 2023). Models were simplified by removal of non-significant interactions using and AIC values using ‘drop1’ function of ‘car’ package. Where there were significant interactions, Tukey HSD in ‘emmeans’ package was applied. See metadata for details of each file. These raw data were collected using the following instruments/meters and/or protocols. Environmental conditions: Air temperature (°C) and humidity (%) measured using iButton® climate loggers (DS1923; iButton®, Alfa-Tek Australia) and vapour pressure deficit (VPD; kPa) was calculated from temperature and humidity. Used the manufacturer’s software for download to csv files. PAR (µmol m-2 s-1) was measured with a Li-190R Quantum Sensor and LI-250A light meter (Li-COR, Lincoln, Nebraska, USA). Used the manufacturer’s software for download to csv files. Wind speed (ms-1) measured using a digital anemometer (435; Testo, Testo SE & CO.KGaA, Lenzkirch, Germany). Used the manufacturer’s software for download to csv files. Plant responses: Were measured on replicate leaves or plants for each of the treatment combinations of species (Solanum orbiculatum or Solanum oligacanthum), season (spring or summer), nutrient treatment (high or low) and heat stress treatment (ambient or heat stress). Leaf temperatures (°C) monitored using a non-contact infrared thermometer (accuracy ± 2.5%°C; IP67; Jaycar, NSW, Australia) and a thermographic camera with emissivity set to 0.95 (accuracy ± 2°C or ± 2% of m.v.; Testo 885-2; Testo SE & CO.KGaA, Lenzkirch, Germany). Thermographic images were processed using the manufacturer’s software (Testo IRSoft, v4.4). Leaf water potential (ΨL; MPa) was measured using a pressure chamber (Model 1505D; PMS Instrument Company, OR, USA). Total leaf protein per fresh weight (mg g-1) was extracted following Knight (2010) and total protein amount determined using BCA assay using BSA as a standard. Chlorophyll fluorescence (dark adapted Fv/Fm) was collected pre-dawn using a mini-PAM (Heinz Walz GmbH, Effeltrich, Germany). Used the manufacturer’s software for download to csv files. Membrane stability was assessed via electrolyte leakage measured using a conductivity meter (TetraCon 925; WTW, Weilheim, Germany). Plant biomass (g) of above- and below-ground oven-dried biomass. Organs (leaves, stems and roots) were separated at time of harvest and oven-dried and weighed. Damage and survival were visually assessed. Flowers, fruits and seeds were manually counted. Flowers and fruits were removed at time of harvest and oven-dried and weighed.