Search

Upland cotton (Gossypium hirsutum L.) growth and development during the pre-and post-flowering stages are susceptible to high temperature and drought. We report the field-based characterization of multiple morpho-physiological and reproductive stress resilience traits in 11 interspecific chromosome substitution (CS) lines isogenic to each other and the inbred G. hirsutum line TM-1. Significant genetic variability was detected (p < 0.001) in multiple traits in CS lines carrying chromosomes and chromosome segments from CS-B (G. barbadense) and CS-T (G. tomentosum). Line CS-T15sh had a positive effect on photosynthesis (13%), stomatal conductance (33%), and transpiration (24%), and a canopy 6.8 °C cooler than TM-1. The average pollen germination was approximately 8% greater among the CS-B than CS-T lines. Based on the stress response index, three CS lines are identified as heat- and drought-tolerant (CS-T07, CS-B15sh, and CS-B18). The three lines demonstrated enhanced photosynthesis (14%), stomatal conductance (29%), transpiration (13%), and pollen germination (23.6%) compared to TM-1 under field conditions, i.e., traits that would expectedly enhance performance in stressful environments. The generated phenotypic data and stress-tolerance indices on novel CS lines, along with phenotypic methods, would help in developing new cultivars with improved resilience to the effects of global warming. [ABSTRACT FROM AUTHOR]

Parental environments (PEs) affect seed quality and might alter the re-establishment of big bluestem grass due to impacts on seed germination. An in vitro study was conducted to quantify the temperature response of seed germination and its interaction with the PE in big bluestem. Seeds developed under eight PEs consisting of a combination of four day/night growth temperatures (GTs) (20/12, 25/17, 30/22, and 35/27 °C) and two CO2 levels (360 and 720 µL L−1) were germinated at eight temperatures (germination temperatures (GRTs)) ranging from 10 to 42.5 °C. Quadratic and modified bilinear regressions best described the cardinal temperatures for the estimated maximum seed germination (MSG) and seed germination rate (SGR), respectively. The average MSG and SGR showed differential responses to the PEs and significantly declined above a 35 °C GRT across the PEs. For the SGR, the minimum and optimum temperatures showed significant differences from other treatments but the opposite response to elevated CO2, while maximum temperatures significantly declined at high (35/27 °C) and low GTs (20/12 °C). Seed quality parameters, individual seed weight, and C and N contents showed a high correlation (R2 > 60) with the average percentage of seed germination and the SGR. Thus, high temperatures for both the PEs (>30/22 °C) and GRTs (>30 °C) could significantly reduce germination, affecting the re-establishment of big bluestem. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max L.) seedlings may be exposed to low or high temperatures under early or conventional soybean production systems practiced in the US Midsouth. However, a wide range of soybean cultivars commonly grown in the region may inherit diverse tolerance to degrees of temperatures. Therefore, a study was conducted in a controlled-environment facility to quantify 64 soybean cultivars from Maturity Group III to V, to low (LT; 20/12 °C), optimum (OT; 30/22 °C), and high (HT; 40/32 °C) temperature treatments during the seedling growth stage. Several shoot, root, and physiological parameters were assessed at 20 days after sowing. The study found a significant decline in the measured root, shoot, and physiological parameters at both low and high temperatures, except for root average diameter (RAD) and lateral root numbers under LT effects. Under HT, shoot growth was significantly increased, however, root growth showed a significant reduction. Maturity group (MG) III had significantly lower values for the measured root, shoot, and physiological traits across temperature treatments when compared with MG IV and V. Cultivar variability existed and reflected considerably through positive or negative responses in growth to LT and HT. Cumulative stress response indices and principal component analysis were used to identify cultivar-specific tolerance to temperatures. Based on the analysis, cultivars CZ 5225 LL and GS47R216 were identified as most sensitive and tolerant to LT, while, cultivars 45A-46 and 5115LL identified as most tolerant and sensitive to HT, respectively. The information on cultivar-specific tolerance to low or high temperatures obtained in this study would help in cultivar selection to minimize stand loss in present production areas. [ABSTRACT FROM AUTHOR]