Abstract
Heat stress studies in rice (Oryza sativa sp.) under extreme weather scenarios generally use constant temperatures to influence the crop responses without relation to actual weather changes. These heat stress studies may have limited implications for future crop yields because elevated temperatures are not based on local temperature fluctuations. This study investigated the night-time air temperature pattern and assessed the status and reliability of available weather station data in four major rice growing states; Arkansas (AR), California (CA), Louisiana (LA) and Texas (TX) using four public weather station databases. Hourly and daily night-time air temperatures from 20:00 to 06:00 were obtained from 1940 to 2018 during the rice growing period. During the 67-year period, a significant increase of 1.12°C and 0.53°C in seasonal night air temperature occurred in CA and AR (P ≤ 0.001) while LA and TX showed minimal to no increase in night air temperature. Across all rice states and years, night air temperature fluctuations ranged between ±0.2°C and ±4°C with the greatest occurred in CA (2.9°C) and AR (4.5°C). Mean night-time air temperature across all states ranged from 22.6°C to 29.5°C with a rate of increase of 0.01°C to 0.02°C per year since 1941. Due to a relatively smaller spatial dataset (from 1941-2018), trend analyses for AR, TX and LA showed modest bias with root mean square errors (RMSE) of 0.5°C to 1.1°C of absolute mean temperature across all locations. Results in this study showed seasonal night-time air temperature change occurred in some major US rice producing states during the last 67-years. This study highlights the need for more weather stations near agricultural farms to reliably derive actual temperature patterns in the rice growing regions.
Highlights
The US is the fourth largest rice exporter in the world which is in part due to intensive production and the highest-yielding rice agroecosystems (FAOSTAT, 2015; Childs, 2019)
Results in this study showed seasonal night-time air temperature change occurred in some major US rice producing states during the last 67-years
Our results showed inconsistencies in predicting air temperature data and historical temperature trends when using the NASA-POWER data for night air temperature trend analysis in some US rice states
Summary
The US is the fourth largest rice exporter in the world which is in part due to intensive production and the highest-yielding rice agroecosystems (FAOSTAT, 2015; Childs, 2019). Among the US major crops produced, rice has the highest average return on investment (USDA-NASS, 2016). Major US rice producing states include Arkansas, California, Louisiana, Mississippi, Missouri and Texas with CA being the highest yielding and AR being the largest harvested areas in the country (USDA, 2018b). Total rice production in the US increased by 128% between 1960 and 2015 with the highest national mean yield reported in 2013 at 8617 kg∙ha−1 for 1 million ha (USDA-NASS, 2016). These remarkable grain yield increases were driven by increased adoption of high yielding, fertilizer efficient, and disease-insect-resistant rice varieties and improved agronomic practices (i.e. irrigation, tillage). In an effort to sustain future US rice production, cropping systems will require significant yield gains per unit land area while conserving natural resources and reducing environmental degradation
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