| Lycium Barbarum L.is a perennial deciduous shrub belonging to the Solanaceae family.It plays important roles in improving soil structure and fertility,reducing harm caused by salt and alkaline conditions,thus is a good plant to control the desertification of land,and is an important medicinal plant.Here,the methods of field plot experiments and pot simulation experiments were combined to study the water use and regulation characteristics of Lycium Barbarum L.This study aimed to systematically investigate the physiological and ecological mechanisms of water absorption,transportation,and utilization by Lycium in an arid farmland ecosystem,to provide an important scientific basis for farm operations and cultivation of new varieties resistant to drought in arid and semi-arid regions.1.The physiological activity of roots and their distribution can reflect the ability of plants to absorb soil water and the source depth of the water absorbed in the soil.The average root activity of wolfberry plants decrease year by year as they age,and the relative root conductivity increases with the age of the plants.The root activity and relative electrical conductivity of plants treated with plastic film mulch increased to 110.2%and 106.9%that of the control,respectively.The root activity of plants treated with straw mulch increased to 104.4%of that of the control,while the relative electrical conductivity of plants treated with straw mulch decreased to 74.4%that of the control.Plastic film mulch treatment can increase the proportion of fine root biomass in the soil,20 to 60 cm deep,in 4-year old plants,comprising more than 60%of the total fine root biomass.With the increasing age of plants,the main fine roots gradually spread outward and become mainly distributed at a distance of between 0and 60 cm away from the stem.Both plastic film mulch and straw mulch treatment resulted in the gradual expansion of the fine roots,and the fine root biomass increased to 117.8%and 110.0%of the control at a distance of 40 to 60 cm from the stem,respectively.2.The water transport rate is directly affected by a plant's hydraulics.Drought stress increased the ratio of root–plant hydraulic resistance from 40.9%to 59.3%,with the variation range in root specific conductivity being significantly greater than that of canopy specific conductivity.The contribution rate of aquaporins to hydraulic conductivity was greater than 49.7%in the roots,and the root specific conductivity under moderate and severe drought stress decreased to 64.66%and 68.99%,respectively,following treatment with mercury chloride.Plastic film mulch and straw mulch treatment increased the average specific conductivity of roots to 109.95%and102.78%of the control,respectively.The P500 value of xylem gradually decreased from-1.259 MPa to-1.379 MPa as the nitrogen content increased,and the threshold value decreased from-0.82 MPa to-1.06 MPa when the water potential of the xylem vessel decreased significantly.The P500 value of the xylem gradually decreased from-1.259 MPa to-1.379 MPa with the increasing age of plants,and the threshold value decreased from-0.82 MPa to-1.07 MPa when the water potential of the xylem vessel decreased significantly.3.The state of water storage directly affects the water supply of plants and their ability to adapt to arid environments.Free water in plants accounted for 68.94%to76.05%of their total water content,with drought stress and nitrogen content changes having more significant effects on free water content than bound water content.With the increasing age of plants,their bound water content changed more significantly than their free water content.The proportion of root-bound water content in the total water content decreased from 28.50%to 26.21%.The overall water capacity in wolfberry plants was stem>root>leaves.The average water capacity of the stems was 0.0789 g·cm-3·MPa-1;the average water capacity of the roots was 0.0638g·cm-3·MPa-1,and the average water capacity of the leaves was 0.0391 g·cm-3·MPa-1at different tree ages.4.The lower a plant's natural water-loss rate,the greater the plant's ability to adapt to an arid environment,and the better the plant's normal water supply.The average rate of change in natural water loss was 1.719 g·g-1·h-11 in the leaves,0.888g·g-1·h-11 in the stems,and 1.347 g·g-1·h-11 in the roots of two-year-old plants.An increase in nitrogen content can slow the rate of natural water loss in wolfberry plants.The average rate of change in natural water loss was 1.677 g·g-1·h-11 in the leaves,1.013 g·g-1·h-11 in the stems,and 1.326 g·g-1·h-11 in the roots at different plant ages,and the natural water-loss rate of the tissues increased with increasing age of the plants.5.The greater the efficiency of water use,the higher a plant's productivity.Nitrogen can promote plant photosynthesis,and the WUEinstnst reached 1.59?mol·mmol-11 following treatment with a high level of nitrogen,and this decreased with increasing plant age.Both drought stress and increased nitrogen content can increase the proportion of stable isotope?13C in plants.The carbon isotope?13C in the branches decreased from-26.52‰to-29.43‰.The soil water-use contribution rate,of 0–30 cm in the shallow layer,gradually decreased with increasing tree age.The soil water-use contribution rate of 30–100 cm of soil moisture to plant water utilization was 81.81%that of the control.The system of water use in wolfberry plants,involves multiple factors that can all influence the source depth of the water absorbed in the soil and the efficiency of soil water absorption by roots.Hydraulic conductivity decreases with increasing plant age and drought conditions.The water conductivity resistance of the roots is greater than that of the aboveground parts.Water retention ability decreased with the increasing age of trees,and have the greater water use efficiency of drought stress.The increase in a plant's age will expand its range of soil water absorption,and mulching treatments can improve the efficiency of soil water absorption,but they all reduce the water assimilation efficiency of a plant. |
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