土壤机械阻力对草地早熟禾根系生长的影响

该文研究了不同沙土配比根系层在干湿状态下土壤机械阻力的变化规律，以及对草地早熟禾根系生长的影响。试验将沙土配比设为11个处理，即m(沙)∶m(沙＋土)从0～100%，每10%为1个梯度。结果表明:处于湿润状态下的土壤机械阻力低于干燥状态下的，随含沙量的增加，两种状态下土壤机械阻力均呈现中间高两边低的变化趋势，在含沙量为50%～60%（即沙粒含量70%～80%）时，土壤机械阻力达到最大值；随含沙量增加，根系生物量及根冠比先降后升，根系总长度、根系表面积及根尖数与沙粒含量均呈显著的指数函数关系，表明含沙量增大到一定程度时，对于根系分蘖、增加根系总量具有促进作用；根系平均直径随沙粒含量增加，呈现先增加后降低趋势，在含沙量为40%～50% (即沙粒含量60%～70%)达到最大值，与土壤机械阻力呈线性正相关。 

Effects of soil mechanical resistance on root growth characteristics of kentucky turfgrass(Poa pratensis L.)

Soil mechanical resistance (SMR) associated with root growth characteristics in kentucky bluegrass (Poa pratensis L.), as affected by root zone sand content, was investigated under water deficit (dry) and good soil moisture (wet) conditions. Eleven m(sand)∶m(sand+soil) ratios were used in this study, with the sand content ranging from 0 to 100% and every 10% was a gradient. The results indicated that SMR was less under wet than dry conditions. As sand content increased, the SMR increased and reached the maximum level at the sand content of 50%－60% (sand particle content at 70%－80%). The SMR responses to sand content exhibited a similar trend under dry and wet conditions. As sand content increased, root biomass and root to top ratio (R/T) declined first and then increased gradually thereafter. Total root length, root tip number and root surface area increased exponentially as sand content increasing. This suggests that an increase in sand content may promote tillering and root biomass. As sand content increased, average root diameter increased and reached the maximum level at the sand content of 40%-50% (sand particle content at 60%-70%), and declined thereafter. A positive linear relationship was found between root diameter and the SMR in this study.