Progeny Test Of Half Sib Families Of Loblolly Pine

The cycle of the tree growth and economic mature is very long.To short the breeding generation span,increase the genetic gain of unit time in a tree many generations improvement program,the early genetic testing is critical for developing successful breeding strategies.Loblolly pine(Pinus taeda L.)is the most commercially valuable forest tree species in the southern United States,with a wide natural rang.This tree had been introduced to China in the 20th century 30 years and become important timber and industrial raw material tree in the subtropical low hilly areas in China.A total of 26 half sibs from loblolly pine first generation clonal seed orchard of at Baishui forest farm,Hunan and a mixed family introduced from second generation clonal seed orchard of loblolly pine in United States as the Control(CK)were included in this study.The tests included annual growth through age 3,the physiological properties in seeding stage,and resistance at 3 years old.The main results are as follows:(1)The growth traits,physiological properties and disease resistance of half sib families were rich in genetic variation among half sib families from loblolly pine first generation clonal seed orchard.This suggested that early selection of family lines can produce a fast-growing and resistant loblolly pine family for forestry production.(2)The mean height of half sib of loblolly pine showed significant differences,but mean diameter height no significant difference in seeding stag.The total N,K and P contents in needles of the family showed significant differences,and there is a significant correlation between seedling height and the total N,P,K contents.The means chloroplast,soluble protein and soluble sugar contents in the needles of half sib seedlings were not significantly different.(3)The mean height and diameter of half sib of loblolly pine showed significantly or very significantly form age one to age three.The family heritability for height ranged from 0.4369 to 0.7317,and decreasing with the increase of age.The family heritability for the ground diameter ranged from 0.3949 to 0.5945,but increasing with the increase of age.Those suggested that height and ground diameter traits of loblolly pine were moderate genetic control,and strong potential for family selection.The disease resistance of the half sib progeny of loblolly pine from three sites was basically the same,and the family heritability was less than 0.3.It showed that the growth environment condition of loblolly pine had a great influence on its resistance to disease.(4)Based on the growth performance of loblolly pine families,all of 26 half sibs could be divided into four types:fast growing type,sub fast growing type,general type and poor type.The average height and ground diameter of fast-growing type was 160.42%and 115.58%of the poor type at age 3.(5)Based on loblolly pine offspring of young forest growth performance at three years,four loblolly pine fast-growing half-siblings family of 6,11,17,39 and 47 were selected.Included in the family of five and a half compatriots 3 year-old average height,ground diameter than mixed family from the second generation of improved material increased by 16.72%13.87%and 7.05%respectively;And all of the families material,compared to the average tree height,ground diameter increased by 21.33%and 7.66%respectively.