This project involved the research of three PhD students. Description of the data collectect and analysis conducted in each case are described below: Student # 1 (Mitch Clifton: University of Sydney) exploring processes that truncate grain-filling after heat events, Thirty-two diverse wheat genotypes were grown from 2017-2019 at multiple field sites in Australia: Narrabri (NSW), Birchip (VIC), Northam (WA) at different times of sowing (TOS): optimum: TOS 1; one month late: TOS 2; two months late: TOS 3 creating 17 unique environments. Complete randomised block designs were used. Traits assessed included heading, anthesis, grain-filling, maturity DAS, plant height, anthesis and maturity biomass, harvest index, yield, TKW, screening percentage, test weight, and protein percentage. Fructans, sucrose, fructose, and glucose were collected from a subset of 7 genotypes of the same sample for grain-filling. D-glucose and sucrose standard curves were used on each plate for determining Water soluble carbohydrates (WSC) concentration. A glasshouse experiment (Camden) on 6 genotypes in controlled environment targeted heat stress treatment during peak fructan synthesis and grain-filling. Genotypes were exposed to vegetative non-lethal heat stress (priming; seven leaf stage; 35/28°C for 48 hours) before subsequent heat stress (38/5°C) applied at 21 days after sowing (DAA). The factorial treatment structure included primed or not primed (P/N) and at 21 DAA plants were either not treated (C) or subjected to two different heat stress durations of either 4- or 7-day (4D and 7D respectively) - P4D, P7D, PC, N4D, N7D, and NC. Photosynthetic ACi curves were collected at block temperatures set at either 20 or 30 °C, then were analysed using plantecowrap in the R-studio environment. Complete randomised block design. Number of datasets generated = 5 Datasets stored in the USyD RDS at \\shared.sydney.edu.au\research-data\PRJ-HT_wheat_C_allocatio Student # 2 (Brad Posch: Australian National University) addressed processes underlying heat-induced changes in night respiration. During the spring of 2017 and 2018 two field experiments with 20 genotypes were sown as three adjacent fields, one for each time of sowing (TOS), and each field consisted of four replicate blocks with 20 plots that were 2.15 x 4 m. Experiments were located in commercial wheat farms in Dingwall and Barraport West, Victoria. Wheat photosystem II heat tolerance was assessed on a diverse panel of 20-24 genotypes were sown at three different times in 2017 and 2018 and two times in 2019. Tcrit was determined (Tcrit = high temperature where components of photosynthetic machinery (Photosystem II – PSII) start to be damaged). Mace and 8:ZWW11 wheat genotypes were grown in controlled environments with different day and night temperatures for three to four weeks. Rates of leaf and root respiration. photosynthesis, leaf temperature, and the Tcrit of PSII were measured. Alternative oxidase pathway (AOX) on respiratory night warming was probed using the inhibitors salicylhydroxamic acid (SHAM) and potassium cyanide (KCN). Flag leaf Tcrit of 54 wheat genotypes was evaluated in 12 thermal environments over 3 years. Photosynthetic capacity was measured in newly developed and pre-existing flag leaves of two commercial wheat cultivars: Mace, high-yielding wheat; and 1704, low-yielding and heat susceptible genotype; under varying temperatures of 15, 20, 25 and 26°C (a common day temperature, Acclimation of Tcrit, instantaneous temperature response functions of photosynthetic capacity (light-saturated net photosynthesis (An), carboxylation capacity of Rubisco (Vcmax) and capacity for electron transport (Jmax)) and changes in metabolite profiles from seedling to anthesis in pre-existing and newly developed leaves were compared. Number of datasets generated = 232 Datasets stored at https://rsbbox.anu.edu.au/Default.aspx?folder=Shared%20Data%2FResearch%2FPS%2FAtkin%20Lab%2FCurrent%20members%2FBrad%2FGRDC%20US00080%20project%20data Student # 3 (Maria Ruiz: University of Sydney) studied the role of morpho-physiological traits in ameliorating heat damage. Thirty genotypes with contrasting yield response under higher temperatures were studied at different times of sowing (TOS) (optimal, late, and very late) at Narrabri (NSW), Normanville and Barraport (VIC), and Northam and Wongan Hills (WA) during the cropping seasons of 2017, 2018 and 2019. Measured traits were: glaucousness, leaf width and length, leaf angle at flowering and rolling, canopy height, normalized difference vegetation index (NDVI), light interception, phenology, grain protein, percentage screenings, thousand kernel weight (TKW), test weight (TW), moisture content and yield. Air temperature was monitored in the canopy profile during the reproductive and grain filling stages by installing sensors in selected genotypes, depending on the year and the experiment. In Narrabri canopy temperature was monitored using infrared sensors (Arducrops, CSIRO) across the 2017-2019 seasons. A data point was recorded every 15 minutes and sent to a CSIRO data interface PhenoSmart. Sensors were fixed on a pole 60 cm from the top of the canopy, facing the plot from a corner at 45º to avoid soil exposure, especially in open canopies. Four genotypes were selected to monitor the albedo and canopy reflectance during anthesis only at Narrabri (NSW) in experiments corresponding to normal and late sowing (TOS 1 and 3) during 2018 and 2019. Albedometers were installed to monitor broadband albedo during flowering for 24 hours in three blocks chosen randomly from the four blocks available in both normal and late sown experiments. One-off canopy reflectance measurements were captured in two seasons (TOS 1 and 3 in 2018 and TOS 1 in 2019) for all genotypes three times a day (early morning, solar noon and mid-afternoon). Albedo per plot was obtained by calculating the average of the full-range spectra, with the following considerations: (i) reflectance measurement was directly convertible into the surface albedo value, assuming a Lambertian behaviour of the surface; (ii) wavelength bands where there is water absorbed (1350–1420, 1800–1950 and 2400–2501 nm) were excluded for albedo calculation to minimise noise and (iii) a different spectroradiometer was used in TOS 3 in 2018 due to sensor availability. Sensitivity analysis was performed to explore the effect of different parameters on canopy temperature in two conditions: water-stressed and well-watered. Canopy temperature ranges for possible favourable and unfavourable combinations of traits was analysed. Number of datasets generated = 32 Datasets stored in the USyD RDS at \\shared.sydney.edu.au\research-data\PRJ-HT_wheat_C_allocatio Locations were the experiments were conducted are below: - The University of Sydney, Plant Breeding Institute, 12656 Newell Highway Narrabri, NSW 2390 (30°16'13.9"S 149°48'17.7"E) - PBI, Camden (34° 1' 3.465"S 150° 40' 4.049"E) - Birchip, Victoria (35° 59′ 0″ S 142° 56′ 0″ E) - Northam, WA (31°25'14.0"S 116°38'39.6"E) - Normanville, VIC (35°48'22.6"S 143°47'04.4"E) - Wongang Hills, WA (30°50'41.6"S 116°45'01.4"E) - Australian National University, ACT (35°16'41.7642"S 149°7'1.8474"E) - Dingwall, VIC (35°48'33.6462"S 143°50'35.8513"E) - Barraport West VIC (36°02'38.0"S 143°32'22.0"E) For further enquires please contact Prof. Richard Trethowan at richard.trethowan@sydney.edu.au