盐胁迫和干旱胁迫对杜梨幼苗生长和根系特性的影响OA

[Objectives]This study aimed to investigate the effects of varying degrees of salt stress and drought stress on the growth parameters and root system characteristics of Pyrus betulaefolia seedlings,providing a theoretical foundation for research on stress tolerance and cultivar improvement in fruit trees.[Methods]P.betulaefolia seedlings were used as the experimental material.Salt stress was simulated using NaCl solutions at concentrations of 0,3,6 and 12 g•L-1(labeled as CK,S1,S2 and S3,respectively),and drought stress was achieved using PEG-6000 solutions at concentrations of 0,50,100 and 200 g•L-1(labeled as CK,D1,D2 and D3,respectively).The growth and physiological parameters were measured,including aboveground morphology,chlorophyll content,root/shoot ratio,root activity and root system architecture.[Results]With increasing salt stress,the seedlings exhibited a notable decline in root length,root surface area,root volume and root number,while the root/shoot ratio initially decreased and then increased.Compared to the control(CK),root activity of the seedlings in S3 treatment prominently decreased by 81.0%,chlorophyll content remarkably reduced by 23.6%,and plant height dominantly shortened by 57.3%;root length,surface area,volume and root number significantly decreased by 80.0%,78.8%,73.8%and 72.5%,respectively.Under drought stress,as stress severity increased,root length,surface area,volume and root number were significantly inhibited,while the root/shoot ratio initially increased and then decreased.Specifically,root elongation growth in D1 treatment was promoted,but the increase of the average root diameter was suppressed.Compared to CK,root activity of the seedlings in D3 treatment prominently decreased by 67.3%,chlorophyll content remarkably reduced by 30.6%,and plant height dominantly shortened by 53.3%;root length,surface area,volume and root number of seedlings significantly decreased by 41.78%,43.97%,70.08%and 45.51%,respectively.[Conclusions]P.betulaefolia seedlings responded to abiotic stress by dynamically adjusting their root/shoot ratio and root system architecture.The salt tolerance threshold was identified as 6 g•L-1 NaCl(S2 treatment),and the drought tolerance threshold as 100 g•L-1 PEG-6000(D2 treatment).Beyond these thresholds,seedling growth and physiological indices were significantly declined.