Table 4 Pearson correlation coefficient (r) for anatomical traits and nitrogen content in four root order of P. nigra seedlings derived from freshly harvested, not stored seeds and those stored at 3 °C, −3 °C, −10 °C, −20 °C and cryopreserved at −196 °C for 24 months obtained from individual black poplar tree (No. 1)

From: Effect of seed storage temperature on fine root development and mycorrhizal colonization of young Populus nigra seedlings