The Effects of Brief Heat During Early Booting on Reproductive, Developmental, and Chlorophyll Physiological Performance in Common Wheat (Triticum aestivum L.)

Abstract

Rising temperatures due to climate change threaten agricultural crop productivity. As a cool-season crop, wheat is heat-sensitive, but often exposed to high temperatures during the cultivation period. In the current study, a bread wheat panel of spring wheat genotypes, including putatively heat-tolerant Australian and CIMMYT genotypes, was exposed to a 5-day mild (34°C/28°C, day/night) or extreme (37°C/27°C) heat stress during the sensitive pollen developmental stage. Worsening effects on anther morphology were observed, as heat stress increased from mild to extreme. Even under mild heat, a significant decrease in pollen viability and number of grains per spike from primary spike was observed compared with the control (21°C/15°C), with Sunstar and two CIMMYT breeding lines performing well. A heat-specific positive correlation between the two traits indicates the important role of pollen fertility for grain setting. Interestingly, both mild and extreme heat induced development of new tillers after the heat stress, providing an alternative sink for accumulated photosynthates and significantly contributing to the final yield. Measurements of flag leaf maximum potential quantum efficiency of photosystem II (Fv/Fm) showed an initial inhibition after the heat treatment, followed by a full recovery within a few days. Despite this, model fitting using chlorophyll soil plant analysis development (SPAD) measurements showed an earlier onset or faster senescence rate under heat stress. The data presented here provide interesting entry points for further research into pollen fertility, tillering dynamics, and leaf senescence under heat. The identified heat-tolerant wheat genotypes can be used to dissect the underlying mechanisms and breed climate-resilient wheat.

An Overview of Factors Affecting the Functional Quality of Common Wheat (Triticum aestivum L.)

“…Reduced wheat crops due to water stress applied during the early stages of grain filling were recorded, among others, by Khan et al [147], Balla et al [4], and Potopová et al [160]. On the other hand, the water deficit applied at each reproductive stage of wheat may lead to a reduction in grain yield, which has already been proven by various authors [133,151,[161][162][163].…”

Heat stress-induced changes in physiological and some biochemical traits of wheat (Triticum aestivum L.) genotypes

“…The spike development period at temperatures beyond the plant's tolerance threshold causes a shorter growth period, resulting in fewer fertile spikes and seeds in the spike (Verma et al 2022). In this regard, Xu et al (2022) have reported comparable results both under controlled and natural eld conditions. Heat stress at the end of the season shortens the seed lling duration and ultimately leads to the production of smaller seeds by accelerating plant ripening (Hutsch et al 2019).…”

Leaf photosynthetic performance is not a key factor affecting grain yield in spring wheat subjected to heat and combined heat and drought stresses

“…Many tillers of LM62 died after the HD stress and therefore significantly more spikes aborted in LM62 compared with Gladius and LM19 ( p < .001), and the final biomass was primarily based on new tillers that had never reached booting. One earlier study found that wheat plants in heat stress started producing new tillers as old tillers died out (Xu et al., 2022). This may be an effect of heat stress leading to earlier maturation (Wardlaw et al., 2002) combined with the high drought severity making the plant unable to translocate carbohydrates from tillers that went into early maturation.…”