Can alternating temperatures be used to estimate base temperature for seed germination?

Abstract

Modelling weed seedling emergence pattern appears to be a promising approach in the development of effective weed management programmes based on the selection of optimal timing of control operations. Thermal and hydrothermal time models propose that seed germination rates are proportional to the amount by which temperature and water potential exceed threshold values for these environmental factors. Hence, base temperature for seed germination is a fundamental biological parameter for the prediction of weed emergence. A series of laboratory experiments were conducted to estimate base temperature in three weed species belonging to the Asteraceae family, predominant in conservation tillage fields in north-eastern Italy. The traditional method based on germination assays at constant temperatures was compared with a method based on assays at alternating temperatures. The latter might represent an alternative to the former for those species which do not germinate or only poorly under constant temperatures. Base temperature was estimated by regressing the reciprocal of the median germination time on temperature comparing two functions, a broken-stick and an exponential-type model. Both models showed good fit to all data in the whole temperature range and in almost all cases provided similar estimates of base temperature. The main result is that, for the weed species examined in this study, the use of alternating temperatures for base temperature estimation appears to be possible. However, further research is required to test if the use of germination assays performed at alternating temperatures can be a suitable method to estimate base temperature of species that have too low germination at constant temperatures.

Effects of Sub-Optimal Temperatures on Seed Germination of Three Warm-Season Turfgrasses with Perspectives of Cultivation in Transition Zone

“…By fitting this model, we could derive the main thermal-time parameters for all the species/cultivars. Nonlinear least squares were used to fit the model and the average daily temperature was used as explanatory variable [37]. A transform-both-sides technique was used to account for heteroscedasticity, with λ = 0 [38].…”

Temperature and storage time strongly affect the germination success of perennial Euphorbia species in Mediterranean regions

“…Thermo-dormancy has also been found in seeds of Lactuca sativa and Euphorbia nicaeensis (Narbona, Arista, & Ortiz, 2007a;Thanos et al, 1989;Vidaver & Hsiao, 1975). Apart from the prevailing temperature level, thermal history also plays an important role, in the sense that several plant species may prefer a fluctuating temperature regime and may not germinate with constant daily temperatures (Cristaudo, Gresta, Catara, & Mingo, 2014;Masin, Onofri, Gasparini, & Zanin, 2017).…”

“…Apart from the prevailing temperature level, thermal history also plays an important role, in the sense that several plant species may prefer a fluctuating temperature regime and may not germinate with constant daily temperatures (Cristaudo, Gresta, Catara, & Mingo, 2014;Masin, Onofri, Gasparini, & Zanin, 2017).…”

Effect of Different Temperatures on the Germination of Callisthene major (Vochysiaceae)

“…According to Liu et al (2013), who studied the effect of temperature fluctuations on germination of 445 species in Tibet, smaller seeds are benefited by temperature variations, germinating faster and decreasing competition for establishment in clearings; however, this is not a strategy adopted by all species. Masin et al (2017) confirm that the use of alternate temperatures is adequate to obtain good germination rates, but more research is necessary to understand all the mechanisms involved.…”