宿根甘蔗幼苗黄化的原因初探

【目的】探明宿根甘蔗幼苗黄化发生的原因，为其综合防治提供科学依据。【方法】在宿根甘蔗黄化发生较严重的蔗区实地调查甘蔗幼苗黄化的症状表现、发病特点和规律，并采样分析正常和黄化蔗地土壤及植株叶片的营养元素含量。【结果】宿根蔗幼苗黄化发生在酸性较强的土壤，土壤有效铁、锰、钙、镁元素含量均低于正常土壤，有效硫含量高于正常土壤，有效硼含量则差异不大；宿根蔗幼苗黄化株叶片的活性铁、全量钙、镁、硫含量低于宿根蔗正常植株，活性锰含量高于正常植株，全量铁、锰含量则表现为病株叶片高于正常植株叶片，全量硼含量则差异不显著。【结论】甘蔗体内的活性铁含量低、活性锰含量过高，导致植株体内铁锰营养不平衡，可能是宿根甘蔗幼苗黄化的主要原因。

Primary research on causes and mechanism of young shoot etiolation in ratoon sugarcane crop

Objective]In order to provide scientific basis for developing comprehensive etiolation control measures, the present studies were conducted to find out causes of seedlings etiolation in ratoon sugarcane. Method]Surveys were conducted in sugarcane fields, severely affected with young shoot etiolation, to investigate the symptoms, causes and mechanism of etiolation in young shoots of ratoon sugarcane crops. Samples of soil and leaves from normal plants and etiolated plants were collected for nutrient analysis. Result]Etiolation symptom of ratoon sugarcane young shoots occurred in the moderately acidic soil (pH of 4.28). The available Fe, Mn, Ca and Mg contents were lesser than those in normal field soils, however the available S content was higher and available B content did not showed any differences. The active Fe, total Ca, total Mg and total S content in leaves of etiolated plants were lesser than those in the normal plants, however, the active Mn, total Mn and total Fe content in such leaves were higher than in normal plants. Similar to soils, B content did not showed significant differences amongst leaves of normal and etiolated plants. Conclusion]The nutrient imbalance caused by lesser active Fe content and higher active Mn content in ratoon cane might be the major causes for seedling etiolation in ratoon sugarcane.