FROST HARDINESS OF KIWIFRUIT BUDS IN RELATION TO SEASONAL CHANGES OF FATTY ACIDS

One-year-old shoots from female kiwifruit vines (cv. “Hayward”) were freshly cut from early October to mid April and were subjected to freezing temperatures.
At the same time buds were collected and kept frozen for fatty acids analysis with gas chromatography.
Fatty acids were measured both in total lipids and in phospholipids extract.

A successive increase in cold hardiness of kiwifruit buds was observed from fall to mid winter.
The subzero temperatures at which 10% and 90% of the buds were injured (LT₁₀ and LT₉₀, respectively) were -5°C and -8°C in early October, while in early February they were -16.5° and -20°C. This was followed by a subsequent decrease of cold hardiness from mid winter to spring (-1.8°C and -8°C for LT₁₀ and LT₉₀ in mid April).

The major fatty acids species identified were palmitic acid (C16:0), stearic (C18:0), oleic (C18:1), linoleic (C18:2) and linolenic acid (C18:3). Palmitic (C16:0) and linoleic acid (C18:2) showed the most significant seasonal changes in both extracts.
In total lipids extract, palmitic acid, which amounted to 16% of total fatty acids (TFA) in early October, decreased to 11% in early February and increased to 19% in mid April.
In contrast, linoleic acid increased from 30% of TFA in early October to 41% in early February and decreased to 23% in mid April.
The unsaturated:saturated FA ratio (Un/S) rose from 3.5 in October to 5.7 in February and decreased to 3.7 in mid April.
Fatty acid composition of phospholipids differed in the proportion of fatty acids but again palmitic acid (C16:0) and linoleic acid (C18:2) were changed significantly.
Palmitic acid (C16:0) decreased from 28% to 24% and finally increased to 37% in mid April.
Linoleic acid (C18:2) increased from 25% to 30% in early February and in mid April amounted to 21% of TFA. The Un/S ratio in phospholipids was lower than in total lipids but it also rose from 1.4 to 1.9 and finally in mid April decreased to 1.4. Double bond index (DBI) did not change during the sampling period.

Freezing temperatures were found to be highly correlated (R²=0,9421) with Un/S ratio of total lipids.

IV International Symposium on Kiwifruit

M. Genitsariotis, E. Sfakiotakis, G. Diamandidis

kiwifruit buds, freezing temperatures, Un/S ratio, fatty acids

https://doi.org/10.17660/ActaHortic.1999.498.21