Root growth, root senescence and root system architecture in maize under conservative strip tillage system

Abstract

Aims A sound root system architecture (RSA) is important for efficient nutrient and water acquisition. The adaptation of root growth and RSA to the special soil structure under conservative strip tillage (ST) system is largely unknown. Methods We describe three-year field experimentation on a meadow black soil in the Northeast China to investigate the RSA and the dynamic root growth of maize under ST by comparison with the conventional tillage (CT). Results Grain yield in ST and CT were not significantly different, but their yield components differed. Compared to CT, grain number per ear was reduced by 4.4%, while 1000-grain weight was increased by 6.6% in ST. Root growth in ST plants was inhibited in the vegetative stage, as indicated by the reduced total root length (by 27.7-40.1%) compared to CT. During post-silking stage, however, the total root length was not different between ST and CT plants. Accordingly, the root xylem bleeding rate in ST plants was 70.7%-449.9% greater than CT plants. Because ST practice caused uneven horizontal distribution of soil bulk density, the RSA became steeper in ST plants compared to CT. Moreover, the D95 of ST plant roots was greater, indicating their roots grew deeper. Conclusions In conclusion, although root growth is inhibited at vegetative stage, the slow-aging and steep, deep roots in ST plants may contribute to larger grain weight by favoring water and nutrient acquisition during grain filling stage. As a result, grain yield of ST plants is maintained though grain number per ear is reduced.