| This study was conducted to investigate three main organic nutrients, two kinds of plant secondary metabolites(PSMs) and three primary elements, and study the spatial-temporal distribution variations, as well as the correlation between some nutrients. Conventional nutrients included the crude protein(CP), crude fat(EE), and crude fiber(CF), which were tested with the Chinese national standard method; PSMs included total flavonoids(TF) and total alkaloids(TA) compounds, which were determined by spectrophotometry; elements included carbon, nitrogen and hydrogen,which were determined by combustion method. The samples(Bashania fargesii), the staple bamboo of Giant Panda, used in the study were collected from Foping Nature Reserve, Qinling Mountains from October 2014 to September 2015.Conventional nutrients analysis results: CP of leaves reduced with the ages increasing, CP of one-year old leaves were the highest(12.33%~19.87%), that of two-year old leaves fluctuated within 11.43%~17.86%, that of three-year range from10.50% to 16.49%. There were highly significant differences between annual and biennial, annual and perennial(P<0.01); while there were significant differences biennial and perennial(P<0.05). Three ages leaves, CP content showed a certain regularity: CP in winter were the highest, while that in summer were the lowest. CP of annual:winter>spring>autumn>summer, CP of biennial and perennial: winter>spring>autumn>summer. Differences among four seasons were not significant(P>0.05). As the elevation increasing, CP changed not significantly. But the maximum value of annual and biennial CP were testified in core area(1500m-1700m). EE content of B.fargesii was very low, the average content was 2.32%, and little difference were tested among different ages. CF content of B. fargesii were different significantly among all ages and seasons, annual- perennial, biennial-perennial, winter-summer, winterautumn, spring-autumn(P<0.01), summer- autumn(P<0.05). In addition, CP content of stem were very low, mean value was 2.10±0.84%. Among three parts of whole stem,there was no significant difference.PSMs analysis results: the TF content analysis showed that the difference of thecontent of TF in different bamboo ages was very little(P>0.05). But the difference of TF content in different ages of bamboo in each season was very significantly.The prominent feature was that the content in winter and spring were significantly higher than that in summer and autumn. The maximum value of therophyte in winter was 2.99%, the minimun value was 0.81%, the maximum value of biennials was 2.86%, the minimum value was 0.47%, the maximum value of perennial was 3.08%, the minimum value was 0.92%. The highest values of three different bamboo ages all appeared in the higher altitude locality(HAL) of B. fargesii,and reached the hightest value in December, and the lowest value appeared in the lower altitude locality(LAL). TF content of bamboo leaves reached the lowest value in autumn, the average content of therophyte was 0.69%, the biennials reached 0.79%and the perennial reached 1.06%. The analysis of the distribution of different altitude area showed that the content of total flavonoids content increases as the altitude rises.The average content at lower edge area was 1.36±0.06%, the average content at the core area(CA) was 1.65±0.07%, and the average content at HAL was 1.83±0.11%.There exists significant differences between the LAL, CA, and HAL, especially there is a significant difference between CA and HAL. The correlation analysis of TF content and elevation showed that there exists an extremely significant positive correlation between them. According to the results of total alkaloids(TA) : the TA content of annual B. fargesii bamboo leaves gradually changes with the change of bamboo ages, the overall trend is: therophyte>biennials>perennial, the content of the therophyte ranged from 1.87% to 5.46%, average content was 3.27%; the content of biennials ranged from 2.14% to 4.56%, average content was 3.06%; the content of perennial leaves ranged from 2.10% to 4.51%, the average content was 3.00%. There was a significant difference between therophyte and biennials, and an extreme significant difference between therophyte and perennial, but there was no significant difference between biennials and perennial. TA contents had great seasonal differences, and the overall trend was: winter>spring>summer>autumn. The content level was the highest in winter, the highest value of TA in the leaves of different bamboo ages appeared in January, the maximum value of total alkaloids of in winterof therophyte, biennials and perennial appeared at the altitude of 1700 m, 1700 m, and1900 m respectively, which were all at the HAL of B. fargesii distribution. TA and seasons showed an extremely significant correlation, but little with elevation.The results of fundamental elements and component correlation analysis showed that there were little difference of carbon and nitrogen content with bamboo ages and altitudes changing, but obviously associated with the seasons change. Carbon content performed as spring>>summer>>winter>autumn. That of spring was significantly higher than that of winter, summer, and the average content was 49.47%; For the nitrogen element, average content of spring and summer was 3.97% which was significantly higher than that of autumn and winter 3.31%. Hydrogen did not fluctuate with altitudes, seasons and ages changing significantly. The flavonoids content which takes C as the basic elements has significant negative correlation with crude fiber content, and not related to crude protein; the alkaloids content with N as the basic elements was significantly positively correlated with crude protein content, and crude fiber; total flavonoids and total alkaloids are significantly correlated.Comprehensive conclusion: the primary nutritions and PSMs content in B.fargesii were different with bamboo parts, altitudes and seasons differing. TF related mainly to altitude and seasons, which appeared regularly changing as winter/spring>>summer/autumn, and HAL>CA>LAL; while TA related mainly to bamboo ages and seasons, with overall trend of winter>>spring>summer>autumn, young leaves > old leaves. Based on the PSMs hypothesis and self-therapy hypothesis, We assume that the foraging strategy of giant panda, and the seasonal migration were determined by those primary nutrients, as well as the role of PSMs of which the specific components and mechanism remain to be researched. Based on the results, we recommend that some PSMs with special physiological function should be taken into the evaluation system for bamboo nutrition indexes, which were helpful to the breeding management guidance of captive giant panda as well as the habitats choice of giant panda to be reintroduced; in addition, as a diet specialist, giant panda could be used as an ideal model species for the adaptive evolution study between the phytophagous mammals PSMs. |
PDF Full Text Request