Study On Agricultural Characters And Molecular Cytogeneties Of New Strains Of Tetraploid Hybridization Wheatgrass

To breed new tetraploid hybrid wheatgrass varieties, chromosome doubling plants were obtained from the reciprocal crosses seeds between diploid A. mongolicum Keng and A. cristatum cv.’Fairway’ with colchicine treatment, two new strains SZB-01and SZB-02of tetraploid hybrid wheatgrass were bred. This research mainly focused on agronomic characters, such as growth and development, morphology, yield, drought and salt resistance, nutrients and so on, cytogenetics and feature of DNA fingerprint. The main results were as follows:1. The new strains of tetraploid hybrid wheatgrass was higher, the average height of SZB-01was94.11cm and SZB-02was99.88cm; the leaves were significantly wider and larger than reciprocal hybrid F1; the spike of SZB-01reached3.32cm, was wider than contrast, and SZB-02reached9.22cm, was longer than others.2. Two new strains regreened earlier, tillering ability was stronger, and growth stage was over200days. They had higher fertility, the pollen fertility rate of SZB-01was83.39%, and SZB-02was85.30%; the seed set of SZB-01was67.54%, and SZB-02was69.98%.1000-grain weight of new strains were2.897g and2.935g respectively.3. The fresh yield of new strains were higher than A mongolicum Keng, A. cristatum cv. Fairway and reciprocal hybrids F1. SZB-01was24856.72kg/hm2, and SZB-02was25938.35kg/hm2.4. The crude protein content in fresh grass of the two new strains were15.81%to16.13%in blooming stage, the crude fiber content were30.08%to31.32%. The new strains were rich in amino acids, Ca, P and so on.5. Under the draught and salt stress, the seedling membrane permeability of new strains SZB-01and SZB-02increased a little, proline content and POD activity increased more; there were no significant differences in relative cell membrane permeability, proline and POD activity between the two new stains and hybrids F1and A. mongolicum Keng, and there were significant differences between the two new stains and A.cristatum cv.Fairway. It showed that the two new strains inherited the good characters of A.mongolicum Keng which was stronger in drought resistance and salt tolerance.6. Chromosome pairing behavior at PMCM I of two new strains were regular, the chromosome pairing configuration was2n=4x=28=14Ⅱ, the ratio of bivalents were over 99%and the genetic behavior of chromosome was stable.7. Eleven suitable SSR primers had been selected, and DNA fingerprint of two new strains SZB-01and SZB-02of tetraploid hybrid wheatgrass was built by PCR amplification. The genetic distance (GD) of six tested plants were ranged from0.3506to0.7541. Using the GD value of0.47as threshold, six tested plants could be clustered into four groups.