连作对高粱生长及根区土壤环境的影响

以玉米－高粱轮作为对照，研究连作对高粱生长、产量的影响及根区土壤中酶活性和微生物的变化。结果表明：高粱连作3年对产量的抑制开始显现。与轮作相比，连作3年高粱的株高、茎粗、叶面积、生物量显著降低，连作4年更为明显；连作4年高粱根系生长也明显受到影响，0~40 cm深度范围内根系的生物量、根表面积和根体积分别仅为轮作的61.5％、84.4％、73.8％。连作4年增加了土壤中可培养真菌数量，在拔节期和灌浆期分别是轮作的1.9、1.3倍，而对细菌和放线菌的影响没有明显规律；连作显著增加土壤中过氧化氢酶、蔗糖酶的活性，分别比轮作增加了14.7％、17.2％。由此可见，连作不仅抑制高粱植株的生长，并对土壤中微生物区系组成和酶活性产生显著影响。

Effects of sorghum continuous cropping on the growth of sorghum and soil environment

To study the effect of continuous cropping on sorghum growth, yield, the variation of soil enzyme activity and micro-organism, the corn-sorghum rotation was employed as control. The results showed that a significant inhibition on growth and yield was observed when the sorghum was continuous cropping for 3 years. The sorghum continuous cropped for 3 years signifi-cantly decreased the plant height, stem diameter, leaf area and biomass, the difference was more obvious in 4 years. Sorghum continuous cropping for 4 years also had a severe influence on the root growth. Particularly, in the depth between 0~40 cm, compared with the index of corn-sorghum rotation, the root biomass, root length, root surface area and root volume collected for sorghum continuous cropping were 61. 5%, 84. 4%, 73. 8% respectively of those of the corn-sorghum rotation. Meanwhile, The number of fungi in continious cropping soil was 1. 9 times and 1. 3 times of that in rotation at jointing stage, and at the fill-ing stage. There was no apparent pattern for the change of bacteria and actinomyces with continuous cropping for 4 years. Be-sides, the catalase activities and invertase activities of continuous cropping for 4 years was increased by 14. 7%, 17. 2% than that of the rotation cropping. It included that the sorghum continuous cropping restrained the growth of sorghum, and significant-ly impacted the soil microflora and enzyme activity.