Abstract:

To explore the dynamic characteristics of maize root growth in the northeast black soil region after the change from traditional tillage to conservation tillage, and evaluate the suitability of conservation tillage and the feasibility of minirhizotron technique, the minirhizotron technique was used to continuously monitor maize roots in situ under three tillage methods, including no tillage (NT), rotary tillage (RT) and strip tillage (ST), and compared with the traditional soil drilling method. The results showed that the influence of tillage treatments on root morphological indexes gradually extended from surface to subsurface soil with the growing period, and the influence indexes also increased with it. It was found that more than 65% of maize roots under different tillage treatments distributed in 0-30 cm soil layer. After seedling stage, the total root length and root length density of ST treatment were significantly higher than those of other treatments, while the differences were significant only at maturity stage (P<0.05). The regulation of root configuration and distribution by tillage methods was mainly achieved by influencing soil water content and penetration resistance. The average water content of ST was the highest in the whole soil profile. The soil penetration resistance of NT in 0-15 cm soil layer was significantly higher than that of ST and RT, with the highest value of 1558.20 KPa. The soil penetration resistances of all treatments in 15-45 cm soil layer were very close. The relative error of maize root length density obtained by minirhizotron method and that obtained by soil drilling method was basically less than 10%. In this experiment, the change of tillage method could significantly affect root morphological characteristics such as root surface area, volume, diameter and root length density, etc. Soil water content and penetration resistance also had great influence on crop roots. The root length density obtained by minirhizotron method had good correlation with that obtained by soil drilling method. The combination of the two methods would be useful in monitoring the dynamic growth of crop roots in future.

Key words: minirhizotron technique, tillage operations, maize, root length, morphological characteristics