GEOGRAPHICAL VARIATION OF GROWTH RHYTHM, HEIGHT, AND HARDINESS, AND THEIR RELATIONS IN HIPPOPHAE-RHAMNOIDES

Genetic variation in growth rhythm, hardiness and height of 24 populat ions from 3 subspecies in sea buckthorn (Hippophae rhamnoides) were st udied in a field test. The relative variance component of subspecies v aried from 26.2% to 73.7% of total variance. Subspecies turkestanica h ad a growth mode of late start-late finish, ssp. rhamnoides, intermedi ate start-early finish and ssp. sinensis, early start-intermediate fin ish. Subspecies rhamnoides had a growth period of 129 days, approximat e to 30 days shorter than the two Asian subspecies. The average height of ssp. rhamnoides was 43.7 cm, about one-third of that for ssp. turk estanica and sinensis. Subspecies rhamnoides was more hardy than ssp. sinensis, which was still more hardy than ssp. turkestanica. The varia nce among populations was generally comparable with within population variance. Except for hardiness, variations for all characters were muc h larger in ssp. rhamnoides than in ssp. sinensis. The total genetic v ariance (subspecies plus population) varied from 50% to 84% of total v ariance for all characters, except 37% for secondbracts. Later growth cessation was correlated with longer growth period, taller plants, mor e severe frost and winter damage. Strong clinal variation showed that the higher the latitude, the earlier the growth cessation, the shorter the growth period and plant height, the more hardy the population. Th e results indicated that population selection should be an efficient w ay for growth rhythm and plant height. Clinal variation provides guide lines for seed and plant transfer as well as plant introduction. With limited collection and management capacity in germplasm conservation, the recommendation is to collect fewer individuals in each population but more populations along latitude.