Germplasm Evaluation And Hybridization Study Of Helianthus Tuberosus L.

Helianthus tuberosus L. is a sunflower species crop. It can tolerate drought and cold stresses, adaptable to various kinds of environments, especially in the arid-lands of Northwest China. This species plant can yield a large amount of biomass and contain high nutrition value. It provides sustainable raw material for forage, food and other industries. Therefore, a well evaluation of its germplasms will help us to better identify the potential resources for application.We collected 65 germplasms from China and Europe and evaluated their traits in Minqin and Yuzhong respectively. The physiological phenotypes, yields and qualities were analyzed using various methods including variance analysis, correlation analysis, factor analysis and cluster analysis. The results were as follow:(1) H. tuberosus shows great variations among accessions on the phenotype traits, yielies and qualities. The phenotypic cluster analysis indicated that all involved germplasms could be divided into 7 groups:early maturity and small tuber group, European early maturity group, middle maturity group, Chinese high-yielding middle-later maturity group, European high-yielding middle-late maturity groups, late maturity group. The maturity period, morphology and yields significantly vary among groups. Statistics of yield and quality traits revealed that the tuber yield per plant ranged from 0.37kg to 2.79 kg, the total sugar content of tuber dry-mass ranged per plant from 593.93g/kg to 713.37g/kg and the inulin content of tuber dry-mass per plant ranged from 573.67 g/kg to 695.20 g/kg.(2) The two factors analysis indicated that genotype and genotype×environment interaction affected yield significantly. Environment may have delivered significant effect on all traits except the rhizome length and tuber dry-material. Genotype, environment and their interaction significantly affected the content of ash, crude protein, total sugar, reducing sugar, crude fiber in tubes. Crude fat was only affected by environment. Genetype and genetype X environment interaction significantly affected the inulin content of tubes.(3) The correlation analysis indicated that the fresh tuber yield per plant is positively correlated with stem number, branch number, max tuber weight and average tuber weight; meanwhile, it is negatively correlated with the rhizome length and tuber dry weight. For each accession, total sugar content is positive correlated with inulin content and tuber crude fat content and fresh tuber yield, but negatively correlated with crude protein and tuber dry weight.(4) The fesrh tuber, total sugar and inulin content of 27 germplasms were evaluated in Minqin and Yuzhong. The accession with higher fresh tuber yield always shows higher total sugar and inulin yield. The germplasm accessions J1, N2, W1 showed higher yeild than the 110% average yeild in both sites; accessions B3, B5, B2, J2, S and 12, JN2, R4, R2 showed high yield than the 110% average yeild in Minqin and Yuzhong, respectively.(5) According to the cluster analysis of yield factors, the germplasm accession DK6 possesses the highest tuber yield, DK17,12, DK4 have the potential to generate large above-ground biomass.Meanwhile, the cluster analysis of both yield and qulity factors suggested that DK16, DK8, DK5, DK6 and DK7 have the potential to generate high fresh tuber, total sugar and inulin yield.(6) Among H. tuberosus accessions, great variations of capitulum number per plant (from 8 to 116) were detected, but the tubular flower number per capitulum (from 57 to 83) showed small variation.The average achene set of open pollination was less than 25% and the average achene set of self-pollination were less than 1%. Parthenocarpy of H, tuberosus was not detected in this study.Hybrid seed set varied among different combinations. Female parents and interaction of female and male parents both showed significant influence on hybrid seed set. However, the male parents did not show any significant impact on the hybrid seed set, and seed set of the open pollination or self pollination of female parents were not correlated with hybrid seed setDifferent reciprocal cross outcomes were mainly affected by combination of the parents and the open pollination seed sets of female parent but it’s not influenced by the reciprocal method.