Growth Rhythm And Early Selection For Young Pinus Kesiya Planations Of Half-sib Families In South Yunnan,China

Pinus kesiya is one of the most valuable tree timber species in the tropics because of its high quality,fast growing and resisitance to barren soil.This study took P.kesiya family as meterials,growth rhythm and shooting law of P.kesiya,Pinus kesiya var.langbianensis,Pinus taeda and Pinus elliottii×caribaea was compared.Growth rhythm and shooting law for fast-(?)and slow-(?)growing families of P.kesiya was found.In addition,genetic parameters was estimated,correlations of growth traits and stem-form traits was analyzed,genetic variation of families was explored,what's more,superior famiies and individuals were selected,which can support important reference for tending and early selection of P.kesiya.The main analysis conclusion are as follows:(1)There were significant differences(p<0.01)in DBH,height and whorled branches among P.kesiya,P.kesiya var.langbianensis,P.taeda and P.elliottii×caribaea at age 3.P.kesiya performed best and P.taeda performed wrost in 4 species.Different growth patterns were observed among 4species.P.kesiya and P.kesiya var.langbianensis performed that: the highest growth rate of the DBH was in the first fast-growth stage,the most growth increment was in the second slow-growing stage,the growth advantage of height was mainly showed in the first fastgrowing stage and the third fast-growing stage.P.taeda showed its growth advantage of DBH in the first fast-growing stage and height growth performed better in the second fast-growing stage;P.elliottii×caribaea showed that: the most growth increment and highest growth rate of the DBH was in the first fast-growth stage,and its highest growth rate in the second fast-growth stage,most growth increment in the second slow-growth stage for height.P.taeda shooting 1~6 times a year,3~5 times were the most.P.elliottii×caribaea shooting 1~6 times a year,3~5 times were the most.4 species were recommended that tending management should be conducted before the peak of DBH and height growth,combined with the raining it was considered for pruning in January.(2)There were significant differences(p<0.05)in DBH,height and shooting times among 17 families of P.kesiya at the age of 3.There were 13 families superior to the control P.kesiya var.langbianensis about its DBH and height.Families 7 performed best,and families 71 had the worst performance among 17 families.After clustering,similar growth patterns were found in fast-growing(?)and slow-growing(?)families,but the annual growth increment were quite different.Compared with families of type ?,type ? showed their growth advantages of DBH in the second fast-growing stage and slow-growing stages rather than the first fast-growing stage,and their height growth performed better in the first and second fast-growing stages and the third slow-growing stage.The height was not synchronized with the DBH growth rhythm of the tree,while the height growth behind the shooing period.P.kesiya var.langbianensis and P.Kesiya shooting 1~4 times,and 2 times was the most,4 times was the least.In addition,spring and summer's shoot ratio were higher,and there were more cases shooting 2 times in summer.Additionaly,the results of canonical correlation analysis was 0.9988,the most important factor was monthly average temperature with the value of 0.429,and the second factor is monthly lowest temperature with the value of-0.2324.What's more,the value of height is the largest in growth traits with the value of 7.442,the value of DBH is-3.617.It showed that monthly average temperature is the great influence on tree height.(3)Survival of P.kesiya was more than 90% at the age of 2,3.5,and 4.5.Significant difference(p<0.05)were observed in families and blocks among DBH,height,volumn,survival,internode length and branch diameter.There were significant difference(p<0.01)in branch numbers only among families,and significant difference(p<0.05)in main trunk numbers only among blocks.The family heritability(?_N~2)of DBH,height and volumn were 0.604,0.620,0.653,respectively,individual heritability(?_N~2)were 0.199,0.225,0.243,genetic variation coefficient were 7.24%,12.78%,0.8%,phenotypic variation coefficient were 17.33%,13.41%,38.13%.From age 2 years to 4.5 years,family heritability(?_N~2)and individual heritability(?_N~2)of DBH declined from 0.657 and 0.233 to 0.604 and 0.199.However,family heritability(?_N~2)and individual heritability(?_N~2)of height and volumn fluctuated from age 2 years to 4.5 years,the fluctuation was small.genetic variation coefficient(CV_g)and phenotypic variation(CV_p)coefficient of DBH,height and volumn declined with age.Various ages of its family heritability(?_N~2)and individual heritability(?_N~2)changed slightly,genetic variation coefficient and phenotypic variation coefficient declined with age.The family heritability(?_N~2)of branch numbers,stem-striaghtness,internode length,branch diameter and trunk numbers were 0.698,0.478,0.448,0.663,0.637,respectively.Individual heritability(?_N~2)were 0.271,0.122,0.089,0.231,0.210,genetic variation coefficient were 7.13%,8.9%,21.33%,5.31%,10.32%18.26%,,phenotypic variation coefficient were 36.76%,44.3%,29%,32%.Significant relation(p<0.01)were observed between DBH and height of P.kesiya at age 2a~4.5a.Similar significant(p<0.01)relation were observed between growth trait and stemform traits.In additional,significant(p<0.05)relation were found in branch numbers to internode length,branch number and branch diameter,and branch number to branch diameter.21 families were selected according to standard ?,6 families were selected according to standard ?.There were 105 superior individuals from 21 families according to comibines selection,96 superior individuals from 32 families according to family selection,100 superior individuals from 66 families according to mass selection.