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Genetic variation in growth rhythm, hardiness and height of 24 populations from 3 subspecies in sea buckthorn (Hippophae rhamnoides) were studied in a field test. The relative variance component of subspecies varied from 26.2% to 73.7% of total variance. Subspecies turkestanica had a growth mode of late start-late finish, ssp. rhamnoides, intermediate start-early finish and ssp. sinensis, early start-intermediate finish. Subspecies rhamnoides had a growth period of 129 days, ≈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. tarkestanica and sinensis. Subspecies rhamizoides was more hardy than ssp. sinensis, which was still more hardy than ssp. turkestanica. The variance among populations was generally comparable with within population variance. Except for hardiness, variations for all characters were much larger in ssp. rhamnoides than in ssp. sinensis. The total genetic variance (subspecies plus population) varied from 50% to 84% of total variance for all characters, except 37% for secondbracts. Later growth cessation was correlated with longer growth period, taller plants, more 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. -The results indicated that population selection should bean efficient way for growth rhythm and plant height. Clinal variation provides guidelines 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.