Abstract
With continued global warming, the frequency and severity of heat wave events increased over the past decades, threatening both regional and global food security in the future. There are growing interests to study the impacts of drought on crop. However, studies on the impacts of heat stress on crop photosynthesis and yield are still lacking. To fill this knowledge gap, we used both statistical models and satellite solar-induced chlorophyll fluorescence (SIF) data to assess the impacts of heat stress on wheat yield in a major wheat growing region, the Indo-Gangetic Plains (IGP), India. The statistical model showed that the relationships between different accumulated degree days (ADD) and reported wheat yield were significantly negative. The results confirmed that heat stress affected wheat yield across this region. Building on such information, satellite SIF observations were used to further explore the physiological basis of heat stress impacts on wheat yield. Our results showed that SIF had strong negative correlations with ADDs and was capable of monitoring heat stress. The SIF results also indicated that heat stress caused yield loss by directly impacting the photosynthetic capacity in wheat. Overall, our findings demonstrated that SIF as an effective proxy for photosynthetic activity would improve our understanding of the impacts of heat stress on wheat yield.
Highlights
Wheat is one of the most widely grown crops in the world and plays a vital role in global food security
This study analyzed the relationships between accumulated degree days (ADD) and wheat yield using statistical models, to assess the impacts of heat stress on wheat yield across the Indo-Gangetic Plains (IGP)
The results showed that Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) could capture the interannual variation in wheat yield better than Global Ozone Monitoring Instrument 2 (GOME-2) solar-induced chlorophyll fluorescence (SIF), which was opposite to their results [9]
Summary
Wheat is one of the most widely grown crops in the world and plays a vital role in global food security. High temperatures can cause heat stress in wheat, especially during the grain-filling stage [1]. Excessive heat can accelerate leaf senescence and shorten grain-filling duration, resulting in yield loss [2,3,4]. With increasing risks of high temperatures under global warming, yield loss due to heat stress could be the main issue to the major wheat-producing regions [5]. In the Indo-Gangetic Plains (IGP) of India, heat stress has already caused great yield loss in wheat over the past few decades [6,7,8]. In 2010, extreme heat stress affected this region and caused a significant reduction of wheat yields [9]
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