Screening for Cold Tolerance during Germination within Sweet and Fiber Sorghums [Sorghum bicolor (L.) Moench] for Energy Biomass

Abstract

Within the project “BIOSEA” funded by the Italian Ministry of Agriculture and Forestry, a preliminary laboratory test was conducted to assess the variability for cold tolerance during germination in 30 cultivars of biomass sorghum, among fiber and sweet types. Seed germination (%) and mean germination time (MGT) were examined at seven constant temperatures (from 8 °C to 35 °C) and base temperature (Tb) and thermal time (θT) for 50% germination were calculated. A wide genetic diversity in the germination response of sorghum was ascertained at 8 °C (CV 45%) and 10 °C (CV 25.4%). At 8 °C, in cultivars of ‘Padana 4’, ‘PR811F’, ‘PSE24213’, ‘PR849’ and ‘Zerberus’, seed germination exceeded 80%. Seeds of ‘Zerberus’ were also the fastest, requiring less than 13 days for final germination at this low temperature. Great differences were found in Tb and θT among cultivars. Tb varied between 7.44 °C (‘PR811F’) and 13.48 °C (‘Nectar’). Thermal time (θT) was, on average, 24.09 °Cd−1, and ranged between 16.62 (‘Nectar’) and 33.42 °Cd−1 (‘PSE24213’). The best combination of the two germination parameters (i.e., low Tb and θT) corresponded to ‘Zerberus’, ‘Sucrosorgo 506’, ‘Jumbo’ and ‘PR811F’. Accordingly, these cultivars are more tolerant to cold stress during germination and, thus, more adapt to early spring sowings in Mediterranean areas (March-April). Cultivars ‘PR811F’ (fiber type) and ‘Sucrosorgo 506’ (sweet type) also combine high cold tolerance with good productivity in terms of final dry biomass, as assessed in open-field conditions (late spring sowing). The genetic variation in the germination response to a low temperature is useful for the identification of genotypes of sorghum suitable to early sowings in semi-arid areas. Selection within existing cultivars for cold tolerance during germination may also contribute to the expansion of biomass sorghum into cooler cultivation areas, such as those of Northern Europe, which are less suitable to this warm season crop.

Germination Response of Different Castor Bean Genotypes to Temperature for Early and Late Sowing Adaptation in the Mediterranean Regions

“…The slope b of the regression line is the germination rate with a decreasing temperature (the higher the b, the faster the germination with the temperature increase). The abscissa intercept is an estimate of the theoretical minimum temperature of germination (Tb) [20,21]. The thermal time (θ T ) needed to achieve 50% germination (θ T(50) ) at the temperatures evaluated was calculated according to the following equation:…”

Preliminary Evaluation of Minor Cereals as Non-Traditional Brewing Raw Materials

“…1, Cytiva, Malborough, MA, USA) wetted with 4 mL H 2 O. The samples were placed in a dark thermostat at 20 • C, except for sorghum, which was incubated at 25 • C [22] (Figure 1). Germinated seeds were counted after 24, 48, 72, 96 and 120 h. For each sample, three replicates of 100 seeds were performed.…”

Breeding Sorghum for Grain, Forage and Bioenergy in Brazil

“…(2017) also reported a reduction in chlorophyll synthesis in cold conditions, reducing photosynthesis and production. Genetic variance for cold tolerance has been reported in grain, sweet, and biomass sorghum (Patanè et al, 2021;Franks et al, 2006), as well as QTLs, which can be helpful for marker-assisted selection (MAS) (Parra-Londono et al, 2018b;Burow et al, 2011). Furthermore, heterosis for cold tolerance has also been identified, and more tolerant hybrids development can be exploited (Schaffasz et al, 2019;Windpassinger et al, 2017).…”