Sorghum genotypes differ in high temperature responses for seed set

High Temperature Effects on in vitro Pollen Germination and Seed Set in Field Pea

“…Similarly, seed set percentage was positively correlated with in vitro pollen germination in sorghum across genotypes and temperature regimes (Nguyen et al 2013;Singh et al 2015Singh et al , 2016. Specifically, in vitro pollen germination had a weak or no relationship with seed set percentage at lower temperatures (31.9 and 32.8°C), whereas pollen germination was positively correlated with seed set percentage at higher temperatures (36.1 and 38.0°C; Singh et al 2015). The current findings with field pea and those from sorghum (Singh et al 2015) suggest that under control conditions, pollen viability and germinability are not constraining factors for seed set.…”

“…In vitro pollen germination has been used to screen heat tolerance in many crops (Kakani et al 2002(Kakani et al , 2005Salem et al 2007;Devasirvatham et al 2012;Song et al 2015;Singh et al 2015Singh et al , 2016. On the other hand, Petkova et al (2009) suggested that to assess heat-tolerant cultivars of field pea, in vitro pollen-tube length is more reliable than pollen germination percentage because successful fertilization depends on whether pollen tubes actually reach the ovules.…”

“…Indeed, with 64-72% of genes in vegetative tissues of Tradescantia and maize also being expressed in pollen (reviewed by Hamilton and Mascarenhas, 1997), in vitro pollen germination has been investigated as a rapid screening criterion for tolerance to a variety of agronomically-important characteristics including soil acidity and salinity, metal and herbicide toxicity, as well as for heat tolerance (Sari-Gorla and Frova, 1997). Exposure to high temperatures reduces in vitro pollen germination percentage and pollen-tube length in many crops including canola (Singh et al 2008;Morrison et al 2016), cotton (Kakani et al 2005Song et al 2015), and sorghum (Nguyen et al 2013;Djanaguiraman et al 2014;Singh et al 2015Singh et al , 2016, as well as legumes like chickpea (Cicer arietinum; Devasirvatham et al 2012), field pea (Pisum sativum; Petkova et al 2009;Lahlali et al 2014;Jiang et al 2015), groundnut (Arachis hypogaea; Kakani et al 2002), and soybean (Glycine max; Koti et al 2005;Salem et al 2007). In sorghum, seed-set percentage (the number of seeds filled at physiological maturity divided by the total number of florets) was strongly and positively associated with in vitro pollen germination across genotypes and temperature regimes (Nguyen et al 2013;Singh et al 2015Singh et al , 2016.…”

Disaggregating sorghum yield reductions under warming scenarios exposes narrow genetic diversity in US breeding programs

“…Although sorghum is known to be highly heat-tolerant, it is prone to yield losses during the flowering and/or postflowering phases (12,13,27). Sorghum's response to heat stress has been primarily quantified by imposing stress at predetermined stages using highly controlled environment facilities or field-based tents (8)(9)(10)(11)(12)(13)27) involving few cultivars.…”

“…Sorghum's response to heat stress has been primarily quantified by imposing stress at predetermined stages using highly controlled environment facilities or field-based tents (8)(9)(10)(11)(12)(13)27) involving few cultivars. These findings under controlled conditions limit our ability to develop robust conclusions regarding sorghum's heat-stress sensitivity (28).…”