Inner Mongolia Plateau Desert Caragana Is (of Caragana) Four Kinds Of Plant Hydraulic Architecture Characteristics Of A Comparative Study

In this paper, we selected four Caragana species which grew in Mongolian desert areas, namely, C. korshinskii, C. stenophylla, C. roborovoskyi, C. tibetica, studied their hydraulic architecture characteristics and water metabolism; compared the drought resistance that hydraulic architecture characteristics reflected; analyzed the relationship of water transport efficiency and environmental factors; compared water transport characteristics of the four Caragana species from the relationship of hydraulic architecture and water metabolism; compared the changes of hydraulic architecture characteristics of C. korshinskii under different weather of the same season; discussed the pipe model's characteristics of C. korshinskii. The results showed that:(1) the water transport efficiency comparison of one year old twigs as follows:C. korshinskii> C. roborovoskyi> C. stenophylla> C. tibetica. Water transport efficiency of the four Caragana species existed seasonal changes and daily changes, and the changes of C. korshinskii were largest, this showed C. korshinskii was more prone to embolization, and the regulation ability of stomatal behavior was better than others. (2) The four Caragana species can adjust water metabolism according to the changes of environmental conditions, and creat different rates of water metabolism in different seasons. In summer, when drought stress increased, transpiration of the four Caragana species has decreased, C. korshinskii had the largest decreasing amount. Therefore, the compared results of drought-resistant and water-retention capability as follows:C. korshinskii> C. roborovoskyi> C. stenophylla> C. tibetica. (3) In summer, although the drought resistances of the four Caragana species were different, they can regulate the water transport strategies with their structural features. C. korshinskii had better water status, it had large transpiration, the sensitivity of leaves to drought stress was also higher; while the water was not good for C. tibetica, the situations were just the opposite, which was a kind of adaptation for plants to arid environments. (4) Under different weather conditions, the water transport efficiency of C. korshinskii was different, water stress was serious and water transport efficiency was low in sunny day; water conditions were relatively good, and water transport efficiency was high in cloudy day. (5) Constriction area existed in plant xylem water transport of C. korshinskii, the hydraulic conductivity of non-constriction area was higher than that of constriction area. Regardless of constriction area or non-constriction area, the greater stem diameter, the higher water transport efficiency. This showed that the position of plant xylem must be considered if the pipe model theory be used to water transport.