Comparative Study on the Growth Characteristics and Resistance to Rust Disease of Populus deltoides Saplings Among Different Families

The growth characteristics and resistance to rust disease of the 1-year old saplings from progeny populations of 6 crosshybridizing combinations were observed by taking Populus deltoides as the parental. The results of the statistics and analysis showed that the seedling height of all the 6 families was approximately in normal distribution, whereas the basal diameter was not in normal distribution, which was concentrated within 5-9mm. There were extremely significant differences both in height and basal diameter among the families (P<001). The mean height of the 6 families was from 10714cm to 143.35cm, and the mean basal diameter was from 723mm to 838mm. The average seedling height and basal diameter of the best crosshybridizing combination ZS8×2-7 was respectively 33.80% and 1591% higher than those of the worst crosshybridizing combination 2-2×2-38. Regarding the resistance to rust disease, some progenies of each family were resistant, whereas some other progenies were prone to it, and the mean infection index of the 6 families to rust disease was from 1881 to 71.59. Among the 6 families, the ZS8×2-33 crosshybridizing combination was more susceptible, while the 2-2×2-9 crosshybridizing combination was highly resistant.