Fluorescence kinetics of different ecotypes of allelopathic wheat varieties at heading stage

The agronomic traits of four ecotypes of allelopathic winter wheat varieties bred in different years were analyzed, and based on which fluorescence kinetics characteristics at heading stage were investigated via fluorescence quench technology. Potato was used as receptor to measure the allelopathic indices of the wheat varieties, and then the relationship of allelopathic potential with agronomic traits and chlorophyll fluorescence kinetics parameters analyzed. With the exception of “Ningdong No. 1”, the agronomic traits (e.g., spikelet number per plant, seed number per spike, 1000-grain weight and yield) of winter wheat varieties gradually increased with breeding history (from “Bima No. 1”, “Fengchan No. 3 to “Xiaoyan No. 22”). Meanwhile, allelopathic potential of the winter wheat varieties enhanced. Two typical chlorophyll fluorescence kinetics parameters increased from 0.19, 0.21 to 0.22 (for Fm') and from 0.12, 0.13 to 0.14 (for F). Fluorescence kinetics was a possible mechanism that could be used to explain allelopathic potential enhancement. That was to say increase in Fm' and F further improved light absorption and transformation by photosynthesis system PS Ⅱ at minimal energy loss. The special character of “Ningdong No 1” might be due to its narrow adapted area and special ecological property. Significant relationships were observed between allelopathic potential and agronomic traits (e.g., plant height, ear length, flag leaf area, spikelet number, grain number per spikelet and 1000-grain weight and yield) as well as chlorophyll fluorescence kinetics parameters e.g., Fm', F, Y(NO), qP and qL. These indices were considered sufficient to assess allelopathic potential of winter wheat at heading stage. Based on the above findings, allelopathic potential of wheat was determined and regulated mainly by plant configuration, and physiology and biochemistry. These traits provided theoretical support for regulating crop allelopathic potential, and screening and breeding of allelopathic crop cultivars.