| Hybridization is an important way for lily breeding. It can combine the favorable gene independently. New variety will be obtained when genes showed in field. But lily breeding has cross incompatibility significantly. The hybrid seeds may also be obtained by false hybrids. In most lily species, the cold tolerance is strong, but the heat resistance is weak. In this paper, four wild lilies and two lily cultivars were used as parents. Four cross-combination for wide cross breeding were designed, which were Lilium callosum×Lilium regale, Lilium callosum×'Snow Queen', Lilium pumilum(provenance of HeiLong-jiang)×'Siberia', Lilium pumilum(provenance of ChengDe)×'Siberia'respectively. Distant hybrids was obtained successfully by cut-style pollination and ovary culture; They were identified by morphology and RAPD molecular identification. The heat resistance of lily hybrids and thier parents were studied.The main results were as follows:1. Obtaining of hybrid seeds. Using artificial emasculation and cut-style hybridization method, we obtained the embryo seeds successfully in Lilium callosum×Lilium regale, Lilium callosum×'Snow Queen', Lilium pumilum(provenance of HeiLong-jiang)×'Siberia'and Lilium pumilum(provenance of ChengDe)×'Siberia'. The seed set ratio were 27.0 %, 1.4 %, 0.04 % and 0.08 % respectively. The cross-compatibility was low; Study on embryo in vitro after twenty days from pollinated.2. The identification of hybrids. The distant hybrids were used as explants for tissue culture and rapid propagation. Then the seedlings were identified by morphology and RAPD molecular identification.The morphology identification showed that some hybrid plants were matroclinous which may be false hybrid. RAPD molecular identification showed that the hybrids not only had banding come from their parents , but also extraordinary banding which were absent of their parents. Determination showed that hybrids of Lilium callosum×Lilium regale, Lilium callosum×'Snow Queen', Lilium pumilum(provenance of HeiLong-jiang)×'Siberia',Lilium pumilum (provenance of ChengDe)×'Siberia'were true hybrids.3. Through rapid propagation, hybrids and its parents seedlings were used to study the heat resistance.In the cross-combination of Lilium callosum×Lilium regale, Lilium callosum×'Snow Queen',temperature stress for 28℃, the activity of SOD and POD were promoted in the leaves of hybrids. It showed that the treatment of 28℃could promoted the activity of antioxidant enzyme activity; In treatment stage, the trend of soluble protein content was fluctuated. Simultaneously, temperature stress had little effect on Fv/Fm; Temperature stress for 31℃, the root activity of hybrids was strong and reached the peak. The physiological indexes of hybrids lies between parents. Heterosis was significantly. Temperature stress for 28℃and 31℃promoted heat resistance of lily.In the cross-combination of Lilium pumilum(provenance of HeiLong-jiang)×'Siberia', Lilium pumilum (provenance of ChengDe)×'Siberia', temperature stress for 31℃promoted the chlorophyll content and root activity significantly and reached the peak. Hybrids lies between the parents or better than their parents, there was significant correlation between the two indexs(P<0.01); At 37℃, the Proline content of the two hybrids reached the lowest(P<0.05), the content of the hybrids was higher than parents; At 34℃, the Relaxation time increased significantly and conductivity decreased significantly, and hybrids was better than male parent. The two indexs had significant correlation(P<0.05). The Heat Resistance of Lilium pumilum(provenance of DaQing) was higher than Lilium pumilum(provenance of ChengDe), and the heterosis of hybrid was significantly; The Heat Resistance of hybrids was similar to female parent, but better than male parent significantly...
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