Abstract: Hippophae tibetana Schlecht. is one of the endemic species of Hippophae L. in the high altitude area of Qinghai-Tibet Plateau and Himalayas. It presents high variety in the size, shape and color of its fruits, the length of fruit stalk, etc. The variation in fruit characteristics such as fruit length, fruit width, indexes of fruit shape, the length of fruit stalk and fruit ornamentation length of 7 natural populations, distributing in the eastern Qinghai-Tibet Plateau, were analyzed statistically in order to study its variation level and geographic variation patterns. The results showed that very significant variation existed among and within populations (p<0.01),except the fruit ornamentation length among populations(p<0.05). Coefficient of variation(CV) ranged between 11.19% and 45.03%, the length of fruit stalk presented the greatest variation (CV was 45.03%), followed by ornamentation length of fruit(CV was 31.97%), fruit width presented the least variation(CV was 11.19%). Phenotypic differentiation coefficients of variance (V_st) ranged from 0.213 3 to 0.629 9 and the mean was 0.489 5. Each of the variation among and within populations accounted for a half of the fruit variation. Correlations analysis indicated that there were very significant correlations among the fruit characteristics (p<0.01) except the fruit length and the length of fruit stalk, fruit width and fruit ornamentation length. There were also very significant correlations between characteristics and geographical factors (p<0.01) except fruit length and altitude, fruit width and latitude and longitude. Some fruit characteristics showed geographic variation gradient.Cluster analysis indicated that 7 populations clustered according to the geographical distance.

Key words: Hippophae tibetana, population, fruit characteristics, phenotypic variation, geographical variation