Study On Variations Of Seeding Traits Of Populus Deltoides Hybrids F₁ And Its Early Selection

In this study, F1 which sum to 789 clones of six cross combinations of Populus deltoids was taken as the main study object. Through experiments in the fields of growth and anti-pest activity of seeding stage, some important traits in seeding were discussed. Early selection of the hybrids F1 were based on three years’ seeding stage investigation in order to provide theoretical foundations for breeding new poplar varieties of our future work. The major research conclusions were as follows:(1) Cutting survival rate of the family LH, LN, NH, NN, SH and SN was 79.37%、77.51%,82.26%,86.08%,81.09% and 83.50% respectively. Neither inside families nor internal families existed significant differences and there were no obvious correlation with Cutting survival rate of its parents.(2) In the year 2007, stock height coefficient variation of the family LH, LN, NH, NN, SH and SN was 11.31%,15.87%,8.43%,14.35%,12.02% and 9.02% respectively and ground diameter coefficient variation was 12.85%,17.20%,12.20%,18.20%,13.44% and 11.68% respectively. In the year 2008, stock height coefficient variation of the family LH, LN, NH, NN, SH and SN was 14.01%,16.57%,9.93%,17.40%,13.66% and12.93% respectively and ground diameter coefficient variation was 15.88%,20.10%,18.04%, 22.97%,18.18% and 16.92% respectively. In the year 2009, stock height coefficient variation of the family LH, LN, NH, NN, SH and SN was 14.63%,16.76%,12.05%, 17.34%,12.30% and 13.59% respectively and ground diameter coefficient variation was 19.57%,22.34%,17.62%,25.29%,18.22% and 20.29% respectively. The results of genetic analysis showed that the broad heritability of seeding height and ground diameter were 0.8228 and 0.7386.(3) The statistical analysis showed that among families, parents and control varieties (P.×euramericana cv.’zhonglin2025’, P.×euramericana ’Nanlin895’), the ratio of leaf length and width, the ratio of midrib length and petiole length, the ratio of the angle between the first lateral vein and the midrib all had very significant differences. The ratio of leaf length and width, the ratio of midrib length and petiole length and the ratio of the angle between the first lateral vein and the midrib of every family lies between its parents. (4) Index of rust infection of the family LH, LN, NH, NN, SH and SN was 80.53%, 50.72%,31.12%,24.64%,37.67% and 41.44% respectively and this showed related to rust resistance of its parents. Infective rate of ulcer was 4.12%,2.16%,15.35%,2.67%, 3.70% and 3.80% respectively and has no obvious correlation with ulcer resistance of its parents. The parasitism rate of longicorn beetles was 0.62%,0.67%,0.20%,0.28%, 1.03% and 0.24% respectively and has no correlation with longicorn beetles resistance of its parents.(5) Take the average increment of seeding height of the whole F1 generation for standard in the process of early selection of seeding stage, the total selection rate was 52.51% and among them the selection rate of the family LH, LN, NH, NN, SH and SN successively were 70.38%,28.50%,90.63%,17.28%,65.22% and 52.21% and that showed significant differences. Compared with the growth increment of control varieties which were used as the major poplar varieties of Hubei province at present for selection criteria, the 18 clones had larger growth increment and had obvious heterosis and practical genetic gain. In the study of the 18 clones, clone LH17 which transgressive heterosis of seeding height and ground diameter was 26.32% and 37.74% respectively had the maximum 3 years average growth increment. The practical genetic gain of seeding height and ground diameter of clone LH05-17 was 4.35% and 1.96% respectively compared to P.×euramericana cv.’Nanlin895’.