Effects of different altitudes on seed morphology and nutritional composition of Torreya grandis ‘Merrilli'

Abstract: 【Objective】Torreya grandis‘Merrilli'is concentrated in the high altitude mountainous areas. Few studies on the effect altitude on the growth and seed nutrition of the tree are available. This work was to evaluate altitude effects on seed morphology and its nutritional composition of T. grandis‘Merrilli'to provide reference for determination of its suitable altitude range.【Methods】T. grandis‘Merrilli'seeds were sampled from each of the 5 locations at different altitudes (65 m, 480 m, 516 m, 565 m and 645 m) with similar managements in Shenzhou, Zhejiang, in September 2017. The morphological and nutritional characters of the sampled seed were analyzed. 11 morphological parameters including aril-seed length, seed length and wide, shell thickness and seed weight and 10 nutritional ingredients including fats, proteins, acid value, peroxide value, palmitic acids and stearic acid were measured. The quantitative indexes of 30 nuts per sample were determined by conventional methods. The method of continuous extraction was used for the determination of fat content. The content of protein was assayed using Kjeldahl determination. The fatty acid composition was determined by Agilent6890 N/5975 MSD. The relative percentage of the oil constituents were quantified by calculating the relative contents based on the peak areas with normalization method. The peroxide value and acid value of seed oil were determined by GB/T 5009.37-2003. Three biological repeats were made for each analysis.The data were processed with SPSS 19.0 for correlation analysis, gradual regression analysis, factor path analysis and determination degree analysis.【Results】The results showed that T. grandis‘Merrilli'seeds had the largest variation coefficient in the aril-seed length weight (13.12%) . The variation coefficient of the other indexes was relatively low (CV<10%) . With the increase in altitude, the aril and seed became longer, and the kernel recovery increased. There was a significant positive correlation between altitude and seed length, kernel recovery and shape index of aril-seed (p < 0.05) . At low altitudes, arilseed had a relatively small shape index. And there was a significant negative correlation between altitude and aril-seed diameter and weight (p < 0.05) . Partial correlation analysis further revealed a significant positive correlation between altitude and seed length (p < 0.05) . Path analysis indicated that arilseed weight and seed length were the main predictable factors affected by altitude. The average oil content and variation coefficient at the 5 altitudes were 48.68% and 3.97%, respectively. However there was no significant difference in crude oil content (p < 0.05) . The protein content decreased with the elevation, and the difference among altitudes was significant. There was a significant negative correlation between altitude and the contents of protein, stearic acid and linoleic acid. However, there was a significant positive correlation between altitude and oleic acid and eicotrienoic acid levels. The contents of eicosadienoic acid, eicosatrienoic acid, oleic acid and stearic acid were also affected by altitude. Partial correlation analysis further revealed that altitude was significantly positively correlated with the contents of eicosaurotrienoic acid, oleic acid and stearic acid (p < 0.05) , the partial correlation coefficients being 0.981, 0.971 and 0.819, respectively. The content of eicosaurotrienoic acid, oleic acid and stearic acid increased with the increase in altitude. The direct effects of altitude on eicosadienoic acid were the highest, followed by those of eicosatrienoic acid, oleic acid and stearic acid. 99.2 % of the four nutritional traits of the seed were affected by the change in altitude.【Conclusion】T. grandis‘Merrilli'seeds had different characters at different altitudes. Changes in altitude affected the 11 morphological traits of the seeds. Variation in elevation affected the morphological characters and the nutritional ingredients in T. grandis‘Merrilli'seed, among of which aril-seed weight and eicosadienoic acid were most largely effected by altitude. T. grandis‘Merrilli'at low altitude had a slightly lower kernel recovery with stubby seeds and heavy and large aril-seed. There was no significant difference in fat content among altitudes. Protein content and linoleic acid content at low altitudes were higher than at high altitudes. The oil, protein, acid value and peroxide value at low altitudes all met the standards of Forestry Industry of the People's Republic of China (LY/T 1773-2008) . The nutrition indexes at an altitude of 65 m also met the basic requirements. It is suggested that T. grandis‘Merrilli'cultivation can be appropriately extended to low altitude areas.