Shifting bloom times helps crops beat rising heat

By studying global temperature trends alongside the diurnal floret opening time (DFOT) of over 100 plant species, the team identified “early-morning flowering” (EMF) as a powerful natural escape strategy. Crops such as sorghum, pearl millet, and indica rice avoid damaging midday temperatures by shifting reproductive events to cooler early hours. This trait significantly improves seed set and reproductive success under heat stress, offering a promising avenue for breeding climate-resilient varieties of rice, wheat, and maize.

Climate-induced heat stress has grown in frequency, intensity, and duration over the past half-century, and projections suggest further worsening by century’s end. Staple crops—including maize, rice, and soybean—often flower during peak summer heat, exposing reproductive processes to temperatures that impair pollination and grain development. Traditional strategies, such as altering sowing dates or developing biochemical tolerance, remain insufficient in multi-cropping systems or rapidly warming regions. Flowering plants, which provide much of the world’s food and habitat, display remarkable diversity in their diurnal blooming habits. These habits, closely tied to circadian rhythms and floral organ physiology, present a largely untapped resource for mitigating heat stress. Based on these challenges, this study investigated the link between DFOT and crop heat escape.

A study (DOI: 10.48130/seedbio-0025-0013 ) published in Seed Biology on 28 August 2025 by Xin Wang, Fen Mao & Shoubing Huang’s team, China Agricultural University, provides a blueprint for developing climate-resilient crop varieties that can maintain stable yields in hotter, less predictable environments.

The researchers conducted a investigation that combined global climate records, field data, and molecular analyses to examine how rising temperatures influence crop reproduction and how diurnal flowering habits help mitigate heat stress. By analyzing temperature data since 1850, with a focus on the hottest months across 50 cropland sites in Asia, Africa, Europe, and the Americas, they found that between 2004 and 2023 daily maximum temperatures during hot seasons rose by 1.25℃ (0.062℃ per year) while the duration of midday heat episodes extended by 1.08 hours (0.05 h per year). Africa recorded the highest mean maximum temperature at 34.0℃ in 2023, while North America showed the fastest rate of warming and lengthening heat episodes. To assess biological adaptation, the team compiled DFOT data from 102 flowering species, classifying them into morning-, midday-, and night-flowering groups. Significant differences in optimum flowering temperatures were observed among cereal crops: 26.1℃ for morning-flowering, 22.3℃ for midday, and 29.3℃ for night-flowering species. Within cereals, maize and indica rice, which flower in early morning, demonstrated higher temperature thresholds for seed set (37.5℃ and 37.4℃, respectively) than japonica rice (36.7℃), while sorghum and pearl millet, with night-flowering habits, displayed even greater resilience (38℃ and 42.4℃). Controlled experiments further confirmed that EMF wheat and rice varieties consistently achieved higher seed set under heat stress, and maize also benefited when pollination occurred earlier in the day. At the molecular level, genes such as OsMYB8 and EARLY MORNING FLOWERING 1 were shown to regulate DFOT by modifying lodicule cell wall structures, with homologs identified in more than 60 plant species. Collectively, these findings highlight EMF as a robust, widely applicable escape mechanism to safeguard crop reproduction under intensifying climate-induced heat stress.

By aligning flowering with cooler hours, plants avoid pollen sterility, fertilization failure, and grain loss during heat episodes. Beyond breeding, EMF traits could integrate with crop management, including precision sowing or even drone-assisted morning pollination. The approach also benefits insect-pollinated species, since pollinators prefer cooler morning conditions. Unlike biochemical tolerance breeding, which lags behind the pace of climate change, DFOT manipulation offers an immediate adaptation strategy rooted in natural plant rhythms.

###

References

DOI

10.48130/seedbio-0025-0013

Original Source URL

https://doi.org/10.48130/seedbio-0025-0013

Funding information

This study was supported by the National Key Research & Development Program of China (2023YFD2303304), the National Science Foundation of China (32272214), the 2115 Talent Development Program of China Agricultural University, the Pinduoduo-China Agricultural University Research Fund (PC2023B02006), and the S&T Program of Hebei (225A9908D).

About Seed Biology

Seed Biology (e-ISSN 2834-5495) is published by Maximum Academic Press in partnership with Yazhou Bay Seed Laboratory. Seed Biology is an open access, online-only journal focusing on research related to all aspects of the biology of seeds, including but not limited to: evolution of seeds; developmental processes including sporogenesis and gametogenesis, pollination and fertilization; apomixis and artificial seed technologies; regulation and manipulation of seed yield; nutrition and health-related quality of the endosperm, cotyledons, and the seed coat; seed dormancy and germination; seed interactions with the biotic and abiotic environment; and roles of seeds in fruit development. Seed biology publishes a wide range of research approaches, such as omics, genetics, biotechnology, genome editing, cellular and molecular biology, physiology, and environmental biology. Seed Biology publishes high-quality original research, reviews, perspectives, and opinions in open access mode, promoting fast submission, review, and dissemination freely to the global research community.