Responses of leaf area (LA), stomatal conductance (gs), root length (RL) and root hydraulic conductance per unit of root length (Lpunit) to top soil dryness were investigated. Pigeon pea (Cajanus cajan) and sesbania (...Responses of leaf area (LA), stomatal conductance (gs), root length (RL) and root hydraulic conductance per unit of root length (Lpunit) to top soil dryness were investigated. Pigeon pea (Cajanus cajan) and sesbania (Sesbania sesban) were grown in a vertical split-root system. From sixty-six days after sowing, the top soil was dried while the bottom soil was kept wet. Pigeon pea increased LA while maintaining leaf water potential (ΨL) by reducing gs. Increased transpirational demand through canopy development was compensated for by increasing water extraction in the bottom soil. This was achieved by increasing not only RL but also Lpunit. Sesbania kept constant levels of gs, causing a transient reduction of ΨL. ΨL of sesbania was, then, recovered by increasing only RL, but not Lpunit, in the bottom soil while suspending LA extension, suggesting that sesbania regulated only the root area to LA ratio. This study demonstrated a species-specific significance of Lpunit and coordination among Lpunit, RL, gs and LA in exploitation of wet-deeper soils in response to top soil dryness.展开更多
针对传统的混凝土检测系统检测精度低、成本高、信号处理能力差的缺点,提出了一种一发四收超声信号处理系统。该系统选用200 k Hz的超声,以合成孔径聚焦成像算法为基础,将四路信号整合为一路信号,通过判断回波信号声时、声幅和主频的变...针对传统的混凝土检测系统检测精度低、成本高、信号处理能力差的缺点,提出了一种一发四收超声信号处理系统。该系统选用200 k Hz的超声,以合成孔径聚焦成像算法为基础,将四路信号整合为一路信号,通过判断回波信号声时、声幅和主频的变化来对混凝土质量进行检测,大大增加了混凝土缺陷回波的分辨率,提高了系统的检测精度。实验表明,系统性能稳定,精度高,有广阔的应用前景。展开更多
文摘Responses of leaf area (LA), stomatal conductance (gs), root length (RL) and root hydraulic conductance per unit of root length (Lpunit) to top soil dryness were investigated. Pigeon pea (Cajanus cajan) and sesbania (Sesbania sesban) were grown in a vertical split-root system. From sixty-six days after sowing, the top soil was dried while the bottom soil was kept wet. Pigeon pea increased LA while maintaining leaf water potential (ΨL) by reducing gs. Increased transpirational demand through canopy development was compensated for by increasing water extraction in the bottom soil. This was achieved by increasing not only RL but also Lpunit. Sesbania kept constant levels of gs, causing a transient reduction of ΨL. ΨL of sesbania was, then, recovered by increasing only RL, but not Lpunit, in the bottom soil while suspending LA extension, suggesting that sesbania regulated only the root area to LA ratio. This study demonstrated a species-specific significance of Lpunit and coordination among Lpunit, RL, gs and LA in exploitation of wet-deeper soils in response to top soil dryness.
文摘针对传统的混凝土检测系统检测精度低、成本高、信号处理能力差的缺点,提出了一种一发四收超声信号处理系统。该系统选用200 k Hz的超声,以合成孔径聚焦成像算法为基础,将四路信号整合为一路信号,通过判断回波信号声时、声幅和主频的变化来对混凝土质量进行检测,大大增加了混凝土缺陷回波的分辨率,提高了系统的检测精度。实验表明,系统性能稳定,精度高,有广阔的应用前景。
