Abstract
Extreme temperature events as a consequence of global climate change result in a significant decline in rice production. A two-year phytotron experiment was conducted using three temperature levels and two heating durations to compare the effects of heat stress at booting, flowering, and combined (booting + flowering) stages on the production of photosynthates and yield formation. The results showed that high temperature had a significant negative effect on mean net assimilation rate (MNAR), harvest index (HI), and grain yield per plant (YPP), and a significant positive effect under treatment T3 on mean leaf area index (MLAI) and duration of photosynthesis (DOP), and no significant effect on biomass per plant at maturity (BPPM), except at the flowering stage. Negative linear relationships between heat degree days (HDD) and MNAR, HI, and YPP were observed. Conversely, HDD showed positive linear relationships with MLAI and DOP. In addition, BPPM also showed a positive relationship with HDD, except at flowering, for both cultivars and Wuyunjing-24 at combined stages. The variation of YPP in both cultivars was mainly attributed to HI compared to BPPM. However, for biomass, from the first day of high-temperature treatment to maturity (BPPT-M), the main change was caused by MNAR followed by DOP and then MLAI. The projected alleviation effects of multiple heat stress at combined stages compared to single-stage heat stress would help to understand and evaluate rice yield formation and screening of heat-tolerant rice cultivars under current scenarios of high temperature during the rice-growing season.
Highlights
Rice (Oryza sativa L.) is the primary source of food for the majority of the world’s population and is grown under a wide range of environmental conditions [1]
We aimed to investigate the relative contribution of photosynthetic property parameters to the variability of biomass production and grain yield under high-temperature conditions and to establish the quantitative relationships between photosynthetic property parameters, biomass accumulation, grain yield, and heat degree days (HDD), which combine the intensity and duration of heat stress
We aimed to investigate the relative contribution of photosynthetic property parameters to the variability of biomass production and grain yield under high-temperature conditions and to establish the quantitative relationships between photosynthetic property parameters, biomass accumulation, grain yield, and heat degree days (HDD), which combine the intensity and d3uo-f 19 ration of heat stress
Summary
Rice (Oryza sativa L.) is the primary source of food for the majority of the world’s population and is grown under a wide range of environmental conditions [1]. Recent studies revealed that short-term heat stress during the reproductive growth period has a negative impact on rice growth and grain yield formation [11,12,13,14], and this negative impact on yield reduction is higher than that on yield losses due to seasonal warming losses in global rice production regions [14]. Another significant determinant of the effect of heat stress is the duration of high-temperature exposure. Due to the relationship between temperature intensity and duration, a cumulative temperature above a threshold value appears to have a greater effect [15,16]
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