Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photo...Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dis- sipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.展开更多
Due to autorotation,samaras can fly efficiently and stably to be dispersed over a great distance under various weather conditions.Here,we provide a quantitative analysis of the dynamic stability of free-falling maple ...Due to autorotation,samaras can fly efficiently and stably to be dispersed over a great distance under various weather conditions.Here,we provide a quantitative analysis of the dynamic stability of free-falling maple samara(Acer grosseri Pax)and verify whether they are dynamically stable as observed.Morphological and kinematic parameters were obtained based on the existing experimental data of the maple seed.Then the linearized equations of motion were derived,and the stability derivatives were calculated by a computational fluid dynamics method.The techniques of eigenvalue and eigenvector analysis were also used to examine the stability characteristics.It is found that there are five natural modes of motion of the maple seed:one stable oscillatory mode,one fast subsidence mode,one slow subsidence mode,and two neutral stable modes.The two neutral modes are manifested as the seed moving horizontally at a low speed under disturbance.Results show that the maple seed has dynamic stability in sustaining the steady autorotation and descent,exhibiting a minor horizontal motion when disturbed.These findings can beapplied to biomimetic aircraft.展开更多
基金supported by Knowledge Innovation Program of Chinese Academy of Sciences (KZCX2-YW-335)Program of 100 Distinguished Young Scientists of the Chinese Academy of SciencesNational Natural Science Foundation of China (40673070, 40872169)
文摘Samara is the reproductive organ (seed) for many tree species in arid land in northwestern China. It is ecologically important in population development due to its dispersal function. However, information on its photosynthesis and effect of environmental stresses on its photosynthesis is still very limited. In the present study, responses of photosystem II (PSII) activity in samara and leaf of Siberian maple to short-term chilling/freezing and subsequent recovery potential were comparatively investigated by using polyphasic fluorescence test. The samara had more efficient photosynthesis (Fv/Fm and PIABS) and more efficient electron transport (φEo) but lower energy dis- sipation (DIo/RC) than leaf. Generally, the PSII performance and the electron transport for both samara and leaf were inhibited under low temperature stress, accompanied by an increase of energy dissipation in PSII reaction centers (RCs). PSII of both samara and leaf was not markedly affected by chilling and could acclimate to chilling stress. Short-term freezing could completely inhibit PSII activity in both samara and leaf, indicated by the drop of values of Fv/Fm, PIABS, φEo to zero. PSII functional parameters of short-term dark frozen samara could be largely recovered whereas those of frozen leaf could not be recovered. The higher tolerance of samara to short-term low temperature stress than leaf is of great ecological significance for seed development, population establishment of Siberian maple.
基金supported by the National Natural Science Foundation of China(Grant No.11832004)。
文摘Due to autorotation,samaras can fly efficiently and stably to be dispersed over a great distance under various weather conditions.Here,we provide a quantitative analysis of the dynamic stability of free-falling maple samara(Acer grosseri Pax)and verify whether they are dynamically stable as observed.Morphological and kinematic parameters were obtained based on the existing experimental data of the maple seed.Then the linearized equations of motion were derived,and the stability derivatives were calculated by a computational fluid dynamics method.The techniques of eigenvalue and eigenvector analysis were also used to examine the stability characteristics.It is found that there are five natural modes of motion of the maple seed:one stable oscillatory mode,one fast subsidence mode,one slow subsidence mode,and two neutral stable modes.The two neutral modes are manifested as the seed moving horizontally at a low speed under disturbance.Results show that the maple seed has dynamic stability in sustaining the steady autorotation and descent,exhibiting a minor horizontal motion when disturbed.These findings can beapplied to biomimetic aircraft.
