The Water Absorption, Transport And Distribution And Their Physiological Effects Of Typical Desert Plants In Different Life Forms

As a major limiting factor for plant survival,water plays an important role in desert ecosystems.Under the condition of water restriction,desert vegetation adopts a series of strategies to make use of all available water sources by adapting to the environment.As a very important water resource in arid area,dew is an important factor for plant water balance research.Its importance to desert vegetation has always been a hot issue in the field of ecology.Although the amount of dew is small compared to precipitation and runoff water,it can still affect and even in some cases significantly affect the local plant water balance.Most scholars have studied the phenomenon of dew absorption in plant photosynthetic organs and simple photosynthetic physiology,but there was no in-depth study on the process of how water changes in plants after the absorption of condensed water.Secondly,existing studies mainly focus on the description of water absorption by plants in arid areas,while few reports have been reported on the comparison of water changes after the utilization of condensed water by plants of different life forms.Based on different life types of desert plants in temperate arid regions,this study designed field in-situ control experiments.Through artificial simulation of canopy condensate water,combined with physiological and photosynthetic fluorescence physiology,stable ¹⁸O isotope tracer technology was used to explore the absorption,migration and distribution mechanism of condensate water in desert plants.The main research results are as follows:?1?Under the condition of artificial simulation of canopy condensation water,three kinds of plants:Calligonum mongolicum,Haloxylon ammodendron and Horaninowia ulicina from22:00 to 6:00 am the next day:00 time period,the water value has the change,a reverse water potential gradient in the assimilating shoots of plants through the reverse water potential gradient?leaf?absorption of the condensate to the secondary branch?branch?,the assimilation branches(leaf water potential is greater than the secondary branches?branches?,suggesting that three plants have the ability to absorb water.?2?Different life types of plants have different potential water sources,the results of stable¹⁸O isotope tracer water showed that the absorption of the dew by the three plants was from top to bottom,that is,the assimilation branch?leaf?absorbed the dew and then transported to the secondary branches?branches?and even the roots.Under two treatments of Calligonum mongolicum,¹⁸O was enriched in the rhizosphere soil.Under the treatment of ZG1?Cover 1?and ZG2?Cover 2?,only the assimilation branch of Haloxylon ammodendron was enriched with ¹⁸O,while the content of ¹⁸O in other parts was low.There was a difference in the concentration of¹⁸O between the two treatments of Horaninowia ulicina.,and all organs of plants are involved in the process of water absorption.?3?Light adaptation for three plants under minimal fluorescence?Fo?,the steady-state fluorescence?Fs?,maximum quantum yield of photochemical reaction?Fv/Fm?and effective photochemical quantum yield?Fv'/Fm'?,the actual photochemical efficiency(??PS??,coefficient of photochemical quenching?qP?,the coefficient of photochemical quenching?qN?,electron transport efficiency?ETR?changes of the fluorescence parameters such as the manifestation of Calligonum mongolicum has significantly difference?P<0.05?between Haloxylon ammodendron and Horaninowia ulicina respectively,and Haloxylon ammodendron suffering with no significant difference between the section stab each other?P>0.05?;Haloxylon ammodendron ZG1 processing plant Fo and Fm than CK plants under its value is reduced,while the ZG2 plants significantly increased?P<0.05?;Calligonum mongolicum ZG2 plant(?PS? significantly lower than that of CK plants?P<0.05?,the Horaninowia ulicina parameter under the fluorescence light adaptation such as Fo'?Fm?Fs difference change law,embodied in the CK plants with ZG1 and ZG2 had significant difference?P<0.05?.The photosynthetic and fluorescence parameters can directly reflect the physiological conditions of these three plants after absorption of dew.The physiological activities of plants are mainly restricted by stomata.When the solar radiation increases and photosynthesis is satisfied,stomatal opening begins.At the same time,plants affect transpiration and regulate water potential in plants by regulating stomata.At night,the root system of the plant may expel water to alleviate the stress on the root system.