Root stoichiometric dynamics and homeostasis of invasive species Phyllostachys edulis and native species Cunninghamia lanceolata in a subtropical forest in China

The community species abundance and diversity declined with bamboo invasion had been widely reported worldwide.However,the physiological strategies used during root competition between native species and invasive bamboo are poorly understood.To clarify the mechanisms underlying such strategies,the stoichiometric dynamics and homeostasis of nitrogen,phosphorus,organic carbon in root orders of Phyllostachys edulis(I du[=Ⅰ-Pe,years 1 and 2];Ⅱdu[=Ⅱ-Pe,years 3 and 4]),Cunninghamia lanceolata in transition and pure forests were analyzed.With increasing intensity of bamboo invasion,N,P,and C content of C.lanceolata root orders declined,N and P content in P.edulis rhizome orders declined,while C increased,the stoichiometric ratios in mixed forest interface mainly increased,and the stoichiometric differences within native and invasive species root orders narrowed.Meanwhile,the stoichiometric homeostasis index(H)of elements in the same root order and even the same elements in different root orders were not consistent.H of most root orders(except some HP)was greater than 4,the H ranked order wasⅠ-Pe>Cl>Ⅱ-Pe in mixed interfaces,and the N:P ratio of most species root orders was greater than 16,despite being affected by invasion.Our research concluded that the bamboo invasion narrows stoichiometric differences within root orders,and the juvenile bamboo rhizome has a stronger capacity for homeostatic regulation than in adult bamboo and C.lanceolata,which is a key determinant of bamboo invasion success.

Effects of Different Picking Time and Different Geographical Provenances on Oil Content of Camellia oleifera

This paper studied effects of different picking time and different geographical provenances on oil content of Camellia oleifera. The results showed that different picking time had significant effects on the oil content of cold dew seeds and frost's descent seeds. With the delay of picking time,the oil content of cold dew seeds,frost's descent seeds,dry seeds and oil content of seed kernels were significantly increased.There was a significantly positive correlation between the oil content of fresh fruit of cold dew seeds and frost's descent seeds and the dry seed yield of fresh seeds and the oil content of fresh fruit( P < 0. 05),and the correlation coefficient was greater than 0. 85. Besides,the oil content of seed kernels of cold dew seeds was closely correlated with the seed yield of fresh seeds,oil content of fresh fruit,and oil content of fresh seeds. In the process of C. oleifera breeding,the thin coat,high seed yield and high oil content can be taken as the key research directions for future breeding. The oil content of ordinary C. oleifera seeds in 18 counties( cities) was 36. 42%-63. 33%,indicating that there were significant differences in the oil content of C. oleifera in different geographical provenances. In conclusion,according to the study of different picking time,the recommended picking time of cold dew seeds in Hunan area is around October 10,while the best picking time of frost's descent seeds is about October 30. The oil content of C. oleifera fruit in different geographical provenances is quite different. During the development of C. oleifera fruit,the cultivation and management of C. oleifera should be strengthened to increase the oil content of C. oleifera.