Reproductive success of soybean (Glycine max L. Merril) cultivars and exotic lines under high daytime temperature

Abstract

The objectives were to (a) quantify the effects of high daytime temperature (HDT) from gametogenesis to full bloom on photosynthesis and pod set in soybean (Glycine max L. Merril) genotypes and (b) assess the relationships among photosynthesis, cardinal temperatures for pollen germination, in vitro pollen germination percentage, canopy reflectance, and pod-set percentage. Three field experiments were conducted, and Experiment I had HDT between gametogenesis and full bloom (36.5°C to 38.6°C) compared with Experiments II and III (29.5°C to 31.6°C; optimum temperature). HDT decreased photosynthesis (22%) and pod-set percent (11%) compared with Experiment III. Cultivars had higher photosynthesis and pod-set percent than plant introduction (PI) lines. The cultivars (i.e., IA3023 and KS4694) and PI lines (i.e., PI393540 and PI588026A) were HDT tolerant and susceptible, respectively. The decreased pod-set percentage in susceptible genotypes (PI lines) was associated with pollen characteristics. Significant positive (r ≥ 0.67) association between photosynthesis, cardinal temperatures for pollen germination (T and T ) with pod-set percentage was observed. However, a negative (r ≥ -0.43) association between photosynthesis and pod set with canopy reflectance at visible spectrum was observed. In vitro pollen germination and canopy reflectance at visible spectrum can be used as a high-throughput phenotypic tool for breeding HDT-tolerant genotypes.

Heat stress during flowering in cereals – effects and adaptation strategies

“…Furthermore, heat stress during flowering prevented germinated pollen tubes from reaching the viable embryo sac, resulting in spikelet sterility in rice (Shi et al , ). A significantly positive relationship between pollen germination and spikelet fertility/pod set has been documented in sorghum ( R 2 = 0.79–0.91; Singh et al , ; Chiluwal et al , ), peanut ( Arachis hypogaea L.; R 2 = 0.94; Prasad et al , ), rice ( R 2 = 0.52–0.77; Rang et al , , Shi et al , ) and soybean ( R 2 = 0.52–0.84; Djanaguiraman et al , ). Recent breakthrough achieved by coupling ROS probe with flow cytometry allowed the authors to quantify changes in ROS under heat stress (35°C for 30 min), resulting in a 60% reduction in pollen germination potential in pollen population from different plant species (Luria et al , ).…”

Identification and Characterization of Contrasting Genotypes/Cultivars for Developing Heat Tolerance in Agricultural Crops: Current Status and Prospects

“…Soybean cultivars (IA3023 and KS4694) and PI lines (PI393540 and PI588026A) expressed heat tolerance and susceptibility with high and low P n , respectively (Djanaguiraman et al, 2019). The soybean cultivars had less thylakoid membrane damage than the PI lines.…”

“…In another field study, heat stress (>35/25 • C) reduced pollen viability in lentil by up to 78-83% (Sita et al, 2017b), with heat-tolerant genotypes (IG2507, IG3263, IG3745, IG4258, and FLIP2009) maintaining higher pollen germination (48-50%) than heat-sensitive genotypes (28-33%), which was positively correlated with yield. In soybean, exposure of cultivars (i.e., IA3023 and KS4694) and plant introduction lines (PI) lines (i.e., PI393540 and PI588026A) to heat stress (36.5-38.6 • C) between gametogenesis and full bloom, as compared to control treatment (29.5-31.6 • C; optimum temperature) revealed that the cultivars were more heat tolerant because of greater pollen germination and less distortion in pollen shapes (Djanaguiraman et al, 2019). Combined stress treatment damages the reproductive stages mainly pollen grains to a larger extent (Sehgal et al, 2017).…”

Legumes—The art and science of environmentally sustainable agriculture

“…The identification and characterization of high temperature‐tolerant genotypes is therefore particularly important. The study reported by Djanaguiraman, Schapaugh, Fritschi, Nguyen, and Prasad () showed that increases in the daytime temperatures from gametogenesis to full bloom in field‐grown plants decrease pod‐set in a range of soybean genotypes because of decreased pollen viability. These authors identified heat‐tolerant soybean genotypes in a high‐throughput phenotypic screen (Djanaguiraman et al, ).…”