Intrinsic change of physical and chemical properties of sea buckthorn (Hippophae rhamnoides) and implications for berry maturity and quality

SummaryBerries of seven elite sea buckthorn (Hippophae rhamnoides L.) genotypes of different origins were evaluated for changes in physical and chemical properties during two years with substantial climatic differences. All genotypes shared similar dynamic trends in characters such as berry fresh weight, colour, softness, vitamin C and titratable acidity. Colours changed from green to yellowish green and then to their appropriate fully ripe colours. The fully ripe colour generally signalled the cessation of rapid expansion of berry fresh weight which, in turn, signalled an increased rate of softening. The increase in berry fresh weight correlated strongly and significantly with decline in concentrations of vitamin C and titratable acidity. However, considerable differences existed for glucose and fructose in terms of origins. Genotype Chi (Chinese origin, subsp. sinensis) showed a steady and pronounced accumulation in concentrations of both glucose and fructose. Glucose was the major sugar component detected in genotypes of subsp. rhamnoides, but this sugar showed only limited accumulation up to late August and scarcely altered or even declined during the remaining time. A hybrid F×C (Finnish origin × Chinese origin) displayed similar concentrations of glucose to genotype Chi, but its fructose concentrations were similar to subsp. rhamnoides. This may suggest that the gene(s) for high glucose is/are dominant, whereas those for high fructose are recessive. Climatic conditions did not affect dynamic rhythm greatly, but influenced the magnitude of some traits. The strong ranking correlation for dates of full colours attained during the two years among genotypes indicated that colour is a stable indicator of berry maturity. The coincidence of berry colour, cessation of rapid berry growth, mass expansion, and sugar/acid ratio provides a reliable prediction of harvesting time.