Effects of temperature on flowering phenological traits of Populus euphratica Oliv. and Populus pruinosa Schrenk populations, Xinjiang, China

The aims of this study were to explore the interspecific differences of Populus euphratica Oliv. and Populus pruinosa Schrenk populations and the intraspecific differences of males and females within the same species in flowering phenological traits, and the effects of temperatures on flowering phenological traits in different growth years (2001–2003 and 2013–2015). The results showed that P. euphratica population flowered earlier than P. pruinosa population. Moreover, flowering phenological period of population, number of days of flowering phenological period per population, number of days of flowering phenological period per plant and average number of days of flowering period per plant of P. euphratica population were less than those of P. pruinosa population. The differences between male and female within the same species indicated that the flowering periods of males P. euphratica and P. pruinosa populations were earlier than those of female plants. For both species, flowering phenological traits were significantly and negatively correlated with the average temperatures in previous ten days, previous one month and previous three months of flowering. Both species are sensitive to temperature changes and adjust to the changes by advancing the start of flowering and prolonging the duration of flowering.