Effects of cold stratification and dry storage at room temperature on seed germination of eight desert species from the Hexi Corridor of China

Abstract

Aims We investigated seed germination of eight desert plant species of the Hexi Corridor of China following cold-wet stratification and dry storage at room temperature to better understand seed germination and dormancy characteristics and how these species are adapted to their habitat. Methods Seed viability and initial germination percentage of Glycyrrhiza uralensis, Sphaerophysa salsula, Peganum multisectum, Zygophyllum fabago, Nitraria tangutorum, Lycium ruthenicum, Salsola ruthenica and Asterothamnus centrali-asiaticus were determined. Then seeds of these species were divided into four groups (I, II, III and IV) and stored in a refrigerator ((4 ± 1) °C, moist), cold room in winter ((–5 ± 1) °C, moist), outdoor in winter ((–26 – 10) °C, moist) and room temperature ((20 ± 1) °C, dry) for 60 d. Germination was determined under a constant (20 °C) and an alternating temperature regime (25 °C / 10 °C) with 12 h photoperiod (light/dark) for 30 d. Two main germination indices including germination percentage and T50 (half germination time) were recorded. Data were analyzed by one-way ANOVA and the least significant difference test (LSD) at 5% level. Important findings There were three types of seed responses to cold-wet stratification: germination percentage increased, no change, or decreased. Germination percentage of seeds of P. multisectum and Z. fabago significantly increased following cold-wet stratification of 4 °C and –5 °C, and partially increased following –26 – 10 °C. Germination percentage of seeds of L. ruthenicum significantly increased following 4 °C, –5 °C, –26–10 °C and dry storage at room temperature, with germination of 90%–100%. Seeds of P. multisectum, Z. fabago and L. ruthenicum have slight physiological dormancy. Germination of seeds of N. tangutorum, G. uralensis and Sphaerophysa salsula slightly changed following three cold-wet stratification. Seeds of Salsola ruthenica with non-dormancy (germinated to 84% before storage) decreased their germination following cold-wet stratification of 4 °C, whereas no change occurred at –5 °C, –26 – 10 °C. In addition, the response of germination to incubation temperature varied with species.