为探究东北黑土区从传统耕作转变为保护性耕作后玉米根系的变化特征,评价保护性耕作的适宜性及微根管技术的可靠性,采用微根管技术对免耕(NT)、旋耕(RT)和条耕(ST)等3种耕作方式下玉米根系进行原位监测,并与传统土钻法进行比较.结果表明,耕作方式对根系形态指标的影响随生育期进行逐渐由表层向深层土壤延伸,影响指标也由少到多.不同耕作方式下超过65％的玉米根系集中分布在0～30 cm 土层.苗期以后,ST处理总根长、根长密度明显高于其他处理,但仅在成熟期时差异显著(P＜0.05).耕作方式对根系构型与分布的调控主要通过影响土壤剖面含水量和穿透阻力等来实现.整个土壤剖面ST处理平均含水量最高.0～15 cm土层NT处理土壤穿透阻力显著高于ST和RT处理,最高为1558.20kPa,15～45 cm土层各处理土壤穿透阻力较为接近.微根管法与土钻法测得的根长密度相对误差基本在10.0％以内.本试验条件下,耕作方式转变可以显著影响根表面积、体积、直径、根长密度等根系特征,土壤水分状况和穿透阻力对作物根系生长具有较大影响.利用微根管法获得的根长密度与土钻法所得结果具有较好的相关性,2种方法相结合在今后作物根系生长动态监测中具有重要推广应用价值.
Dynamic Monitoring of Maize Root Growth Under Different Tillage Operations Based on Minirhizotron Technique
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.
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