Photocontrol of Weeds

Abstract

AbstractThe reduction of weed emergence resulting from night‐time tillage in worldwide conducted field trials was very variable. The efficacy of night‐time tillage ranged from a reduction of weed ground cover of 97.5 % to an increase in weed seedling emergence of 80 % compared with daytime tillage. In most of the field trials, the reduction in the weed density as a result of night‐time tillage was <30 %. Important factors affecting this variation were: (1) the different light sensitivity of weed species, (2) the different light sensitivity of populations within the same species, (3) the dormancy status of the seeds, (4) the seasonal and short‐term variation of light sensitivity of seeds, (5) the variation of soil water content and (6) the type of soil tillage implement used. Less important were the small light intensity during night‐time tillage which cannot be excluded, and the penetration of light into the soil the days following night‐time tillage. The influence of different environmental factors on the effect of photocontrol of weeds is rather unclear because there are presumably complex interactions between environmental factors and the light‐dependent germination of weed seeds under field conditions. However, some field trials indicate that dry soil conditions reduce the efficacy of photocontrol of weeds. Several trials in the literature suggest that photocontrol of weeds during daytime using implements with a light‐proof cover was as effective as night‐time tillage. This review summarizes the results in research of photocontrol of weeds (soil cultivation in darkness), particularly those derived from field trials. Moreover, important factors are discussed, which might influence the effect of photocontrol of weeds.