Heterosis and drought resistance assessment of Populus simonii × P.nigra F1 hybrids based on growth traits and leaf anatomical structures
[Objective]30 F1 hybrids of Populus simonii(from Tongliao,Inner Mongolia)× P.nigra(from northern Netherland)were used as experimental materials in this study.Aimed to comprehensive evaluate the growth and leaf anatomical structure traits of the F,hybrids under natural semi-arid conditions,which will provide a basis for selecting poplar varieties with strong drought tolerance adaptability and utilizing parental resources.[Method]Differences,genetic variation analysis,and heterosis analysis were conducted on the growth traits of F1 hybrids at four,five,six years and nine leaf anatomical structure traits at six years.Correlation analysis was used to evaluate the correlation of each parameter.The principal component analysis was used to screen typical leaf anatomical structure traits.The membership function method was used to comprehensively evaluate the drought tolerance.[Result]Growth traits and leaf anatomical structures were significant different among F1 hybrids.The coefficient of variative(CV)of tree height(H)and diameter at breast height(DBH)is 17.28％-19.24％and 28.22％-29.87％,respectively.The H and DBH of F,hybrids at different ages are significantly higher than those of their parents,with a high-parent heterosis rate(RHb)29.27％-36.83％.Partial hybrid clones have exhibited high-parent heterosis(Hb)at H and DBH.The CV of leaf anatomical structure traits is 5.78％-18.82％,with repeatability of which is 0.91-0.97.F,hybrids showed a significant positive mid-parent heterosis in lower epidermis thickness,thickness ratio of palisade to spongy,compaction of leaf tissue,thickness of palisade tissue,and a significant positive Hb in cuticle thickness,lower epidermis thickness and compaction of leaf tissue,with RHb of 1.34％-1.77％.There is a high correlation between various indicators,and compaction of leaf tissue,cuticle thickness,compaction of leaf tissue,palisade/spongy and thickness of spongy tissue were ultimately selected as the main component indicators of leaf anatomical structures for evaluating drought resistance of F1 hybrids.Six clones(02-06,02-01,02-05,02-24,02-03,02-13)with potential of growth and drought tolerance were ultimately selected.[Conclusion]Growth traits and leaf anatomical structure varied greatly in F1 hybrids of P.simonii× P.nigra,which have great potential of selection and heterosis.Anatomical structure of leaves could be used to evaluate drought resistance of F,hybrids.Six clones(02-06,02-01,02-05,02-24,02-03,02-13)with potential of fast growth and drought toterlance were initially selected.These results can provide candidate clones and important information of selecting breeding parents for breeding new high-yield and high resistance poplar varieties in arid areas.
Populus simonii × P.nigragrowthleaf anatomical structuresgenetic variationheterosis
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