莱州湾菊芋(Helianthus tuberosus L.)连作对其生长及种植地土壤生物活性影响的研究

Research on Effect of Helianthus tuberosus L. Replanting on Growth and Soil Bioactivity in Laizhou Bay

为掌握菊芋（Helianthus tuberosus L.）连作年限对菊芋生长及土壤环境的影响程度，促进今后菊芋种植模式合理发展，在大田条件下，利用莱州湾南京农业大学山东莱州“863”中试基地长期菊芋连作定位试验，系统研究了不同菊芋连作年限对菊芋生长、菊芋品质及菊芋种植地土壤生物活性的影响。结果表明：随着连作年限的延长，菊芋生长受到抑制，菊芋块茎产量连作5年后开始下降，连作5a比种植1a降低8％，连作7a降低27％；菊芋块茎蛋白质含量随着连作年限的延长而增加，连作7a蛋白质含量为17．15mg·g^-1，比种植1a高102％，而还原糖与纤维素含量呈先增加而后降低的趋势；菊芋连作严重影响土壤微生物种群结构组成，随着连作年限的延长细菌与放线菌呈先增加而后降低的趋势，而真菌含量在连作年限内一直呈增加态势，连作7a土壤真菌含量比种植1a增加325％；土壤脲酶、脱氢酶、（酸、碱性）磷酸酶、淀粉酶与蛋白酶活性随着菊芋种植地连作年限的延长呈先增加而后降低的趋势，而过氧化氢酶活性则表现为先降低而后上升的态势。菊芋连作4～5a对其生长地及土壤环境已产生了消极影响，连作6～7a连作障碍明显加重。

Helianthus tuberosus is one of the most important energy plants receiving an universal attention day by day due to its outbalance economic use values and relatively strong environmental adaptability. Nevertheless, a kind of crop replants in the same field for a long time often makes its replanting soil diseases and insect pests aggravate and cause replant problem easily. In order to study the effects of replanting years on Helianthus tuberosus growth and its soil environment to promote reasonable development of Helianthus tuberosus planting patterns, the experiments were conducted to systematically research on Helianthus tuberosus growth, tuber quality and soil bioactivity replanting 5 years. The tuber yield replanting 5 years registered a 8% decrease over cropping 1 year with a decrease of 27% replanting 7 years. The discrepancy of stalk yield planting 1 to 5 years was not significant, duplexes of replanting 6 and 7 years, however, was 61% and 58% less than planting 1 year. Root yield planting 1 to 5 years was also not significant, but replanting 7 years decreased by 55% compared with planting 1 year. Plant height replanting 6 years registered a 15% decrease over planting 1 year and replanting 7 years registered a 19% decrease over that of planting 1 year. The discrepancy of main stem diameter was not significant planting 1 to 6 years, whenas, that of replanting 7 years was significant compared with planting 1 year with a 32% decrease. The change regularity of Helianthus tuberosus tuber numbers per plant was not obvious and leaf area changed nonsignificantly during the replanting years. The effects of tuber quality were mainly showed on the changes of protein, reducing sugar and cellulose content. Protein content was increased with prolonged planting. The tuber contained 17. 15 mg·g^-1 protein replanting 7 years, which was 102% above that of planting 1 year. However, content of reducing sugar and cellulose showed an increase at first and then a decrease. Helianthus tuberosus replanting seriously affected the soil microbial structure composition. Content of bacteria and actinomycete presented an increase at first and then a decrease and fungi content was increasing throughout the replanting years. The content of fungi replanting 7 years registered a 325% increase over that of planting 1 year. Activity of soil urease, dehydrogenase, （acid and alkaline） phosphatase, amylase and protease appeared an increase at first and then a decrease, but catalase showed a decrease at first and then an increase. However, catalase activity appeared a decrease at first and then an increase. Helianthus tuberosus replanting 4 to 5 years had made negative effects on its growth and soil environment and replanting 6 to 7 years had made replant problem even serious.