| Quantitative studies on rice root morphology have great development prospect and theoretical significance in improving rice cultivation management and variety updating.This study conducted rice field experiments involving different rice varieties,nitrogen levels and water regimes to analyze the dynamics of root morphological traits,root distribution characteristics.Further the relationship between root and aerial part of the plant,and the relationship between root and yield were developed.The results are expected to provide reference and basis for further studying simulation of rice root.Rice root morphology characteristics including root length,number,length,total volume,surface area and absorption ratio surface index were measured and analyzed.The results showed that most of rice root mor:phological traits increased firstly then decreased,while root morphological traits of II You728 were high than Wuyunjing24 over the same period.There were significant differences in root indices between different nitrogen rates,and each index increased with increasing nitrogen rates.In water experiment,the tendency of various rice root indices is mostly "W3>W1>W2".The characteristics of root growth spatial distribution were analyzed mainly based on the length density during growth period and root length.The results showed that root length and root length density increased with the development process in the same soil layer,and they were maximized at heading stage or milky stage,then decreased,while root length and root length density gradually decreased with soil depth increasing.There were no significant differences in root indices between different nitrogen rates in the same soil layer,and each index increased with increasing nitrogen rates in the same soil layer.In water experiment,the tendency of rice root length and root length density is "W3>W1>W2".The growth relationship between root and shoot mainly focuses on root-shootratio and allometric growth between root and shoot.The rice root-shoot ratio decreased during the growth period.The root shoot ratio decreased with the increase of nitrogen application rate.In water experiment,rice shoot ratio under W3 treatment is maximum.These results showed that nitrogen and water deficiency could promote root growth and development of rice.Different root indices including total root dry weight,total root length,adventitious root number,fine lateral root length,coarse lateral root length,adventitious root length,total root surface area and total root volume and above overground index including leaf dry weight,stem dry weight and its total dry weight were selected to develop allometric growth relationships,and power function(Y=a-Xb,Y is root indexes,X refers to plants over ground indexes and a and b are constant)were used to investigate the allometric growth relationships between root and shoot in rice.The results indicated that total dry weight of leaves had best allometric growth relationships with roots morphological traits.In order to investigate the relationship between rice root and yield mainly analyzes the correlation between total root dry weight,total root length,adventitious roots number,fine lateral root length,coarse lateral root length,adventitious root length,specific root length,root cap ratio and yield over heading and maturity.There were significant positive in root dry weight,total root length,adventitious roots number,fine lateral root length,coarse lateral root length and yield.The R2 of data fitting were 0.746-0.942.However,linear correlation between specific root length,root-shoot ratio and yield were not significant. |
