Assessment of heat stress and cloudiness probabilities in post-flowering of spring wheat and canola in the Southern Cone of South America

Abstract

Episodes of heat stress constrain crop production and will be aggravated in the near future according to short and medium-term climate scenarios. Global increase in cloudiness has also been observed, decreasing the incident solar radiation. This work was aimed to quantify the probability of occurrence of heat stress and cloudiness, alone or combined, during the typical post-owering period of wheat and canola in the Southern Cone of South America. Extended climate series (last 3-5 decades with daily register) of 33 conventional weather stations from Argentina, Brazil, Chile and Uruguay (23ºS to 40ºS) were analysed considering the period from September to December. Two different daily events of heat stress were determined: i) maximum daily temperature above 30ºC (T>30ºC), and ii) 5ºC above the historical average maximum temperature of that day (T+5ºC). A cloudiness event was de ned in our work as incident solar radiation 50% lower than the historical average radiation of that day (R50%). The T>30ºC event increased its probability of occurrence throughout the post-owering phase, from September to December. By contrast, the risk of T+5ºC event decreased slightly, just like for R50%, and the higher the latitude, the lower the probability of R50%. The T>30ºC plus R50% combined stresses reached greater cumulated probabilities during post-owering, compared to T+5ºC plus R50%, being 42% vs. 15% in northernmost locations, 26% vs. 19% in central (between 31ºS to 35ºS), and 28% vs. 1% in southernmost locations, respectively. A curvilinear relationship emerged between the monthly probability of combined stresses and the number of days with stress per month. In summary, T>30ºC was the most frequent thermal stress during post-owering in wheat and canola. Both combined stresses had a noticeable risk of occurrence, but T>30ºC plus R50% was the highest. Evidence of the recent past and current occurrence of heat stress individually, and its combination with cloudiness events during post-owering of temperate crops, serves as a baseline for future climate scenarios in main cropped areas in the Southern Cone of South America.

Frost risk in canola and carinata as a function of sowing date in the agricultural central region of South America

“…This behavior clearly shows the greater photoperiod response of carinata in relation to canola as previously reported by Nanda et al (1996), which is expressed in a 77% higher estimated R p coefficient (1.6 vs. 0.9 for carinata and canola, respectively). However, despite the greater cycle adjustment of carinata in relation to canola, for the commercial range of canola sowing date in the region (early to mid-June) (Rivelli et al, 2021), the flowering date of canola occurs, on average, 15 d before carinata, which determines that the harvest date and seeding of the summer crop is delayed in carinata in relation to canola.…”

“…The period from seed emergence to end of juvenile stage is sensitive to vernalization, while the photoperiod‐induced phase occurs between end of juvenile and floral initiation (Robertson & Lilley, 2016). Synchronizing crop phenology with environment is critical to increase crop production (Hunt et al., 2019; Miralles et al., 2001) as well as to reduce potential yield losses caused by extreme temperatures (Chauhan et al., 2019; Kutcher et al., 2010; Rivelli et al., 2021; Takashima et al., 2013). In this sense, modeling crop phenology is of great interest for adapting strategies to climate change in agriculture (Ceglar et al., 2011).…”

Transcriptome and Physiological Analysis of Rapeseed Tolerance to Post-Flowering Temperature Increase

“…Climate-change-induced temperature fluctuations pose a significant threat to crop production, particularly in the Southern Hemisphere, where strong warming is predicted across various global warming scenarios [1][2][3][4]. Recently, Rivelli et al (2021) reported a temperature increase in the Southern Cone of South America over the past 30-50 years, highlighting the urgency of understanding crop responses to these changes [5].…”

Earliness and morphotypes of common wheat cultivars of Western and Eastern Siberia

“…Wheat is one of the three most wide-spread crops in the world, but, unlike rice and corn, both its winter and spring cultivars are widely cultivated. Spring common (bread) wheat, in this respect, mains a crucial crop for the regions of South and North America, Australia, Central and South-East Asia as well as for those of Northern Asia which have harsh continental climate (Morgounov et al, 2018;Garcia et al, 2019;Rivelli et al, 2021).…”