Root-Sourced Signals, Competitive Ablity And Yield Of Winter Wheat Affected By Water Stress And Root Excision

Pot-culture experiment at the stage of anthesis of winter wheat (Triticum aestivum L.cv'changwul35') affected by root excision simulated as a small root system was conducted to investigate the feature of root-sourced signal under drying soil through root excision as the small root system, and differential adaptation of winter wheat with diverse root system to drought on the basis of root system characteristics and yield, and discussed the competitive ability and the characteristic of photosynthesis and its relationship with yield formation.Main results in this study are listed as follows:1. (one-year experiment from 2004 to 2005) Compares of the feature of root-sourced signals of winter wheat(Triticum aestivum L. cv 'changwul35') with root excision as a small root system grown during progressive soil drying under anthesis were studied. Winter wheat grown in the flowerpots was transferred to environmental controlled glasshouse everyday. The controls were grown at the fully supplied water conditions. It suggests that water deficit in soil would lead to conspicuous reaction of nHRS and HRS. The critical soil water content (SWC) at which nHRS and HRS were triggered successively varied regularly from different root system. The threshold range of wheat with different root system ranged from 60% —48 % FWC (Field water capacity) . Root excision treatment, represented a small root system cultivar, has a wider threshold range from 58.7%—48.1%. Conversely, as a large root system cultivar, root without excision treatment kept a narrower threshold range from 55—48.9% FWC. The results show that the winter wheat which has the small root system has the wide threshold range of 'high upper limit and low lower limit'.2. Non-hydraulic stomatal sensitivity followed the model of double "Z" for the winter wheat with different root system. During the process of the SWC decreasing from 75% FWC (well-watered condition) to 40% FWC (severe stress), three stages can be classed for plants including the stage from 75% FWC to the onset of nHRS (Process 1), the stage from nHRS to HRS (Process 2) and the stage after the appearance of HRS (Process 3). The results show that...