作 者 ：柳洪鹃 史春余 张立明 张海峰 王振振 柴沙沙
期 刊 ：植物营养与肥料学报 2012年 18卷 3期 页码：724-732
Keywords:sweet potato, potassium, storage root, soluble sugar, carbohydrate metabolic enzyme,
摘 要 ：为了探讨钾素提高甘薯块根可溶性糖含量的生理基础。选用典型的食用型甘薯品种“北京553”，设置不同施钾处理，于2009～2010年2个生长季在山东农业大学农学试验站进行试验。采用甘薯块根膨大过程中定期取样的方法，测定块根可溶性糖和淀粉含量及相关酶活性、功能叶蔗糖含量及相关酶活性。结果表明，与对照比较，施用钾肥能显著提高块根产量、可溶性糖及各糖组分含量，其中K2O用量为24 g/m2处理增幅最大，为最适用量。进一步研究发现，适宜供钾处理显著提高了功能叶磷酸蔗糖合成酶活性和蔗糖含量，生育期内平均增幅分别为10.31%和34.13%，同时提高了块根中蔗糖合成酶、不溶性酸性转化酶的活性，生育期内平均增幅为16.47%和3.66%，在提高源端光合产物供应的同时促进蔗糖在库端的卸载，促进块根中淀粉和可溶性糖的积累；适宜供钾处理还提高了块根中α-和β-淀粉酶的活性，生育期内平均增幅分别为26.06%和14.64%，促进淀粉向可溶性糖转化。此外，适宜供钾处理还显著提高了生长前期和后期块根中可溶性酸性转化酶活性、以及生长后期块根中蔗糖-蔗糖果糖基转移酶活性，促进了葡萄糖、果糖和果聚糖在块根中的积累。在甘薯收获期，块根可溶性糖和淀粉含量分别提高了13.52%和3.02%。即钾肥能够增加块根中蔗糖的供应量、促进块根对蔗糖的吸收、促进淀粉水解，是其提高块根可溶性糖含量的生理原因。
Abstract:In order to clarify the physiological basis of increasing soluble sugar content in storage roots of edible sweet potato by potassium fertilization, the typical cultivar of edible sweet potato (Beijing 553) was grown in a replicated experiment at the Agricultural Experiment Station of Shandong Agricultural University in 2 summer crop seasons of 2009 and 2010. The treatments included the control and treatments with different dosages of potassium. The changes of starch content, soluble sugar content and related enzyme activities of storage roots, sucrose content and related enzyme activities of functional leaves were determined by using periodic sampling during the enlargement of sweet potato storage roots. The results show that compared with the control, the application of potassium can increase yield, the content of soluble sugar and its components of storage roots, and the largest increase appears in the treatment with 24 g K2O. In other words, the dosage of this treatment is the optimum one. The sucrose phosphate synthase (SPS) activity and sucrose content of functional leaves are increased significantly, with the average increase of 10.31% and 34.13%, and the sucrose synthase (SS) activity and insoluble acid invertase activity of storage roots are increased observably with the average increase of 16.47% and 3.66% during whole growth period in the treatment with the optimum dosage. These results indicate the transports of photosynthate from functional leaves to storage roots are improved. As a result, the accumulations of soluble sugar and starch in storage roots are achieved. Meanwhile the amylase activities in the treatment with the optimum dosage are increased significantly with the average increase of 27.90% and 14.26%, respectively for α- and β-amylase, which enhances the conversion from starch to soluble sugar. Besides, the treatment with the optimum dosage can increase activity of soluble acid invertase during the pre and post growth periods of sweet potato, and can increase sucrose: sucrose 1-fructosyltransferase (SST) activity at the later growth stage of sweet potato as well. The improvement of soluble acid invertase activity and SST activity is benefit to the accumulation of glucose and fructose in storage roots. At the harvest, the contents of soluble sugar and starch are increased by 13.52% and 3.02% respectively. To sum up, the physiological reasons of increasing soluble sugar content in storage roots caused by potassium application are that it can increase supply of sucrose, promote absorption of sucrose and promote hydrolysis of starch.
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