| Quercus acutissima is a predominant tree species in the deciduous broad-leaved forest, with a wide geographic distribution and big range of ecological conditions in China. These were conducive to the intraspecific genetic differences in aspects of growth and adaptability in phylogenetic generation. Provenance tests of forest trees at common garden, provide valuable data for assessing the response of plant growth to environmental differences between the location of origin and the planting (test) site. In previous study, the 3 Q. acutissima provenance test forests were afforested at the Yongfeng, Jiangxi Province (YF), Kaihua, Zhejiang Province (KH), and Chuzhou, Anhui Province (CZ). In the study, we determined leaf N, P stoichiometry and leaf shape, plant size in 3 Q. acutissima provenance test forests and analyzed the contribution of site (environment) and provenance (genetic) to leaf stoichiometry, explored the pattern and homeostasis of leaf stoichiometry; and studied the correlations between leaf stoichiometry and leaf shape, plant size, revealed the functions of the stoichiometry. The main results were concluded as follows:1. The site (environment) effect was statistically significant on leaf stoichiometry (p<0.05), with 13.21%～66.74% of the total variations accounted for leaf C contents, N contents, P contents, C:N, C:P and N:P, while the provenance effect was insignificant and only accounted for 2.92%～11.04% of total variations for leaf stoichiometry. The leaf N contents and C:N, N contents and N:P, P contents and C:P, P contents and N:P were significantly correlated, and the common SMA (standardized major axis) slope was also observed among three sites and two provenance groups. It can be concluded that the leaf stoichiometry on single species, Q. acutissima, was mainly determined by its growing environment, due to the similar C, N and P biochemical pathways at species level. The stable correlation coefficients among sites and provenances implied the coupling ratios of leaf stoichiometry were independent of environment and provenance, which supported the leaf stoichiometric homeostasis.2. The leaf N, P stoichiometry showed good correlations to leaf shape. The leaf N contents and length, N contents and vein density, P contents and length, P contents and L:W, P contents and vein quantity, P contents and vein angle, N:P and all leaf shape, demonstrated the allometric relationships, but N contents and width showed the isometric relationships. These results reflected the response and adaption of leaves to the high N and low P conditions and nutrient regulation on the investment balance mechanism of leaf architecture construction.The leaf N contents showed significantly co-vary with leaf width, which was due to the leaf width only affected by leaf N contents. The SMA slope of covariation of leaf N and width was significantly lower than -1, displayed the increase rate of D-value of leaf N slower than that of leaf width. It can be concluded that the sensitivity of leaf width was higher than leaf N contents response to the high N condition, and illustrated that the relative stability of leaf stoichiometry.3. Leaf N contents and trees height (H), N:P and H showed the significantly positive relationships, and leaf N contents and ground diameter (D), P contents and H, N:P were significantly negative relationships. The N contents and H, N contents and D, P contents and H showed the allometric relationships, but leaf N:P was isometric in relation to H and D. The leaf N:P and H, N:P and D showed significantly covariations, and respectively were isometric and allometric relationships. All this results were plant balanced the body structure and function, distribution patterns of storage material and nutrient transfer rate to adapt the high N and low P condition. |
PDF Full Text Request