Studies On Growth Dynamics Of Betula Platyphylla Roots And Its Relationship With Temperature

The climate difference between the natural distribution area and the transplanted area of Betula platyphylla,especially its temperature,may be the cause of the growth and development problems such as the low transplant survival rate of Betula platyphylla.Monitoring trees through scientific techniques and finding out the relationship between trees and the environment may be a better solution.Roots are the basis for the growth and development of trees,and the growth dynamics and morphological changes of fine roots can reflect the health of trees.In the spring and autumn,it is the critical period for trees from dormancy to growth and growth to dormancy,often accompanied by problems such as weakened trees and safe wintering.At this time,the growth and development status of the root system is crucial for the trees.We use Betula platyphylla as a test material,to study the growth dynamics(root biomass,root length density,root length,root volume,root surface area,root activity)and morphological changes(root tissue density,specific root length,root specific surface area)of the Betula platyphylla root of 0-1 mm,1-2 mm,and 2-5 mm diameter in 0-20 cm,20-40 cm,and 40-60 cm soil layers in spring and autumn,with the methods of minirhizotron and earth drill.Reveal the growth dynamics and morphological changes of the birch root system in the main season,and identify key indicators to provide technical support for observation and cultivation management of Betula platyphylla.we find that:1.Minirhizotron method(1)The 20-40 cm soil layer can be used as the main soil layer for monitoring the Betula platyphylla root.The roots of Betula platyphylla is mainly distributed in the 20-40 cm soil layer.The root biomass in this soil layer is large,and the fine roots have the highest nutrient use efficiency,and the thick roots have the strongest ability to extend.The temperature change in the soil indicates the start and stop of the growth of Betula platyphylla roots in spring and autumn.(2)Root length can be used as the main index for minirhizotron methods observation.The root length density was calculated from the root length to reveal the ability of the root to absorb water and nutrients.(3)The root growth indexes(biomass,root length density)and morphological indexes(root specific surface area,root tissue density)of Betula platyphylla have spatial heterogeneity,and the morphological indicators did not change significantly during the season.(4)The average daily temperature of the soil when the Betula platyphylla roots begin togrow is 6.5±0.1 ? in the 20-40 cm soil layer in spring.(5)The period of growth of roots in the 0-20 cm soil layer in autumn was from early September(09.04)to mid-September(09.14)for a total of 10 days,and the corresponding soil daily average temperature is 21.2±0.1 ?--21.8±0.1 ?;The period of growth of roots in the20-40 cm soil layer in autumn is from the end of August(08.31)to late September(09.20)for a total of 20 days,and the corresponding soil daily average temperature is19.5±0.1 ?--20.9±0.1 ?;The period of growth of roots in the 20-40 cm soil layer in autumn is from the end of August(08.31)to late September(09.20)for a total of 20 days,and the corresponding soil daily average temperature is 18.8±0.1 ?--20.1±0.1 ?;When the average daily soil temperature in 20-40 cm soil layer is lower than 17±0.5 ?,the growth of Betula platyphylla roots is stopped.(6)A regression model for root growth indexes(biomass,root length)and temperature was established.There is a strong correlation between the fine root growth of Betula platyphylla and the environment and soil temperature.The regression model of the root growth index and temperature fit well and can better estimate the status of fine root growth.There was no significant correlation between soil temperature and root morphology(tissue density,root specific surface area).2.earth drill(7)The specific root length can be used as an index to evaluate seasonal differences in the morphological characteristics of Betula platyphylla roots.(8)The difference in root activity between different diameters was significant,and the finer the diameter,the higher the root activity.The root activity of 0-1 mm diameter can be used as a monitoring index of the physiological activity of the Betula platyphylla roots in spring and autumn.