Ayankojo, I. T., Ayankojo IT, Morgan, K. T., & Morgan KT. (2020). Increasing Air Temperatures and Its Effects on Growth and Productivity of Tomato in South Florida. Plants (Basel), 9(9), 1245.
Abstract: Florida ranks first among US states in fresh-market tomato production with annual production exceeding one-third of the total annual production in the country. Although tomato is a signature crop in Florida, current and future ambient temperatures could impose a major production challenge, especially during the fall growing season. This problem is increasingly becoming an important concern among tomato growers in south Florida, but studies addressing these concerns have not been conducted until now. Therefore, this study was conducted to determine the impacts of the present ambient temperature conditions and planting dates on tomato productivity in south Florida. The study was conducted using crop simulation model CROPGRO-Tomato of DSSAT (Decision Support System for Agricultural Transfer) version 4.7. Five treatments were evaluated, and included AT (simulated treatment using 14 years of actual daily weather conditions at the study location) while other treatments were conducted based on a percentage (-20%, -10%, +10%, +20%) of AT to simulate cooler and warmer temperature regimes. The results suggested that under the current temperature conditions during the fall growing season in south Florida, average tomato yield was up to 29% lower compared to the cooler temperature regimes. Tomato yield further decreased by 52% to 85% at air temperatures above the current condition. Yield reduction under high temperature was primarily due to lower fruit production. Contrary to yield, both tomato biomass accumulation and leaf area index increased with increase in temperature. Results also indicated that due to changes in air temperature pattern, tomato yield increased as planting date increased from July to December. Therefore, planting date modification during the fall season from the current July-September to dates between November and December will reduce the impacts of heat stress and increase tomato productivity in south Florida.
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Heaton, M. J., Sain, S. R., Greasby, T. A., Uejio, C. K., Hayden, M. H., Monaghan, A. J., et al. (2014). Characterizing urban vulnerability to heat stress using a spatially varying coefficient model. Spatial and Spatio-temporal Epidemiology, 8, 23–33.
Abstract: Identifying and characterizing urban vulnerability to heat is a key step in designing intervention strategies to combat negative consequences of extreme heat on human health. This study combines excess non-accidental mortality counts, numerical weather simulations, US Census and parcel data into an assessment of vulnerability to heat in Houston, Texas. Specifically, a hierarchical model with spatially varying coefficients is used to account for differences in vulnerability among census block groups. Socio-economic and demographic variables from census and parcel data are selected via a forward selection algorithm where at each step the remaining variables are orthogonalized with respect to the chosen variables to account for collinearity. Daily minimum temperatures and composite heat indices (e.g. discomfort index) provide a better model fit than other ambient temperature measurements (e.g. maximum temperature, relative humidity). Positive interactions between elderly populations and heat exposure were found suggesting these populations are more responsive to increases in heat.
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Hertzberg, V., Mac, V., Elon, L., Mutic, N., Mutic, A., Peterman, K., et al. (2017). Novel Analytic Methods Needed for Real-Time Continuous Core Body Temperature Data. Western Journal of Nursing Research, 39(1), 95–111.
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Liu, B., Asseng, S., Liu, L., Tang, L., Cao, W., & Zhu, Y. (2016). Testing the responses of four wheat crop models to heat stress at anthesis and grain filling. Glob Change Biol, 22(5), 1890–1903.
Abstract: Higher temperatures caused by future climate change will bring more frequent heat stress events and pose an increasing risk to global wheat production. Crop models have been widely used to simulate future crop productivity but are rarely tested with observed heat stress experimental datasets. Four wheat models (DSSAT-CERES-Wheat, DSSAT-Nwheat, APSIM-Wheat, and WheatGrow) were evaluated with 4years of environment-controlled phytotron experimental datasets with two wheat cultivars under heat stress at anthesis and grain filling stages. Heat stress at anthesis reduced observed grain numbers per unit area and individual grain size, while heat stress during grain filling mainly decreased the size of the individual grains. The observed impact of heat stress on grain filling duration, total aboveground biomass, grain yield, and grain protein concentration (GPC) varied depending on cultivar and accumulated heat stress. For every unit increase of heat degree days (HDD, degree days over 30 degrees C), grain filling duration was reduced by 0.30-0.60%, total aboveground biomass was reduced by 0.37-0.43%, and grain yield was reduced by 1.0-1.6%, but GPC was increased by 0.50% for cv Yangmai16 and 0.80% for cv Xumai30. The tested crop simulation models could reproduce some of the observed reductions in grain filling duration, final total aboveground biomass, and grain yield, as well as the observed increase in GPC due to heat stress. Most of the crop models tended to reproduce heat stress impacts better during grain filling than at anthesis. Some of the tested models require improvements in the response to heat stress during grain filling, but all models need improvements in simulating heat stress effects on grain set during anthesis. The observed significant genetic variability in the response of wheat to heat stress needs to be considered through cultivar parameters in future simulation studies.
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Liu, B., Asseng, S., Wang, A., Wang, S., Tang, L., Cao, W., et al. (2017). Modelling the effects of post-heading heat stress on biomass growth of winter wheat. Agricultural and Forest Meteorology, 247, 476–490.
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Liu, B., Liu, L., Asseng, S., Zou, X., Li, J., Cao, W., et al. (2016). Modelling the effects of heat stress on post-heading durations in wheat: A comparison of temperature response routines. Agricultural and Forest Meteorology, 222, 45–58.
Abstract: Crop yield simulations are highly correlated to reproductive phase duration simulations, which are often affected by heat stress. In this study, we evaluated four widely used temperature response routines of wheat phenology (Bilinear, Sin, Beta, and Trapezoidal routines) to simulate heat stress effects on post heading durations with datasets from four years of environment-controlled phytotron experiments and multi-year field experiments across the main wheat production region in China. Significant reductions in post-heading duration were observed with increasing heat stress in phytotron experiments. A comparison of these temperature routines imbedded in the WheatGrow model showed that three of the routines could not predict post-heading durations under heat stress, while the Trapezoidal routine tended to overestimate high temperature impacts. Therefore, the three routines that could not simulate heat stress effects were extended by a senescence acceleration function. This function significantly improved the post-heading duration simulations under heat stress, regardless of the original temperature routine. However, the temperature threshold of initiating the senescence acceleration function varied depending on the original temperature response routine, between 27.3 and 30.1 degrees C. A new genotypic coefficient representing a cultivar-specific sensitivity to heat stress was introduced and ranged from 1.4 to 5.7 times of none heat-affected senescence per day. When evaluating the three temperature response routines linked with the added senescence acceleration function with independent phenology data (130 measurements), resulted in an average RMSE of 2.2 days for post-heading duration. The improved post-heading duration simulation is important for simulating current year-to-year yield variability due to frequent heat events, and it is even more critical for climate change impact assessments.
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Traylor-Knowles, N., & Traylor-Knowles N. (2019). Heat stress compromises epithelial integrity in the coral, Acropora hyacinthus. PeerJ, 7, e6510.
Abstract: It is well understood that heat stress causes bleaching in corals. Much work has focused on the way heat stress disrupts corals' symbiotic relationship with endosymbiotic algal dinoflagellate, Symbiodiniaceae, a process called bleaching. However, the damage to the coral tissue that occurs during the bleaching process and, importantly, the factors that contribute to subsequent recovery, are not well understood. I hypothesize that the host tissue damage created by heat stress initiates cascades of wound healing factors that maintain epithelial integrity. These factors may be found to contribute to the coral's potential capacity to recover. In this study, I present evidence that heat stress causes damage to the coral host tissue and that collagen is present in the gastrodermis of heat-stressed corals. I found that, during the early stages of bleaching, an important transcription factor for wound healing, Grainyhead, is expressed throughout the gastrodermis, where the cellular and tissue rearrangements occur. Lastly, using phylogenetics, I found that cnidarian Grainyhead proteins evolved three distinct groups and that evolution of this protein family likely happened within each taxonomic group. These findings have important implications for our study of coral resiliency in the face of climate change.
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Traylor-Knowles, N., Rose, N. H., & Palumbi, S. R. (2017). The cell specificity of gene expression in the response to heat stress in corals. J Exp Biol, 220(10), 1837–1845.
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Wang, B., Liu, D. L., Asseng, S., Macadam, I., & Yu, Q. (2017). Modelling wheat yield change under CO 2 increase, heat and water stress in relation to plant available water capacity in eastern Australia. European Journal of Agronomy, 90, 152–161.
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Webber, H., White, J. W., Kimball, B. A., Ewert, F., Asseng, S., Eyshi Rezaei, E., et al. (2018). Physical robustness of canopy temperature models for crop heat stress simulation across environments and production conditions. Field Crops Research, 216, 75–88.
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