木薯氮磷钾营养特性及其施肥效应研究

以传统木薯品种‘华南205’及新育品种‘华南5号’为材料,通过田间试验,研究了不同时期植株养分含量状况,探讨了施肥措施对不同品种养分含量的影响。结果表明,木薯产量与块根生长阶段(块根形成期、块根生长早期、块根快速膨大期)的氮含量和苗期、块根快速生长期和快速膨大期的钾含量显著正相关(P0.01)。淀粉含量与块根形成期的氮含量显著正相关,与苗期及成熟期的磷含量以及成熟期的钾含量显著负相关(P0.01)。施用氮肥显著提高了木薯的氮含量,施用磷肥和钾肥对氮含量没有显著影响。施用磷肥可使木薯的磷含量小幅提高,而仅苗期达到显著水平,氮肥、钾肥对木薯的磷含量也有一定影响。钾肥显著提高了木薯钾含量,氮肥、磷肥对钾含量没有显著影响。‘华南205’和‘华南5号’的氮含量和磷含量对氮肥、磷肥的响应相对一致,但‘华南205’的钾含量对钾肥的响应明显强于‘华南5号’。‘华南205’和‘华南5号’的氮含量和磷含量水平相对一致,但‘华南205’在块根形成期的氮含量显著高于‘华南5号’,而苗期的磷含量显著低于‘华南5号’,‘华南5号’从苗期至块根膨大期的钾含量均高于‘华南205’,其中块根形成和快速生长期的差异达到显著水平。因此,木薯推荐施肥过程中,在均衡氮磷钾养分的基础上,还需结合考虑品种特性。

Cassava nutritive characteristics of NPK and effect of fertilizer application

Cassava (Manihot esculenta Grantz), a perennial shrub belonging to the family of Euphorbiaceae, is grown in Guangdong and Guangxi Provinces of China. Cassava root develops into tubers that form an important source of dietary and industrial carbohydrates. Cassava is the most competitive biofuel crop in terms of clean energy (ethanol and hydrogen) production because of its high starch content and high level of production. Cassava yield is significant related with nutrient content of the plant. To analyze the effects of N, P₂O₅ and K₂O contents at different growth stages seedling stage (SS), tuber root formative stage (TRF), early tuberous root growth stage (TRG), rapid root bulking stage (TRB) and maturity stage MS)] of different cassava varieties, a field trial with five fertilization treatments NP, NK, PK, NPK (in these treatments, the application rates of N, P, and K were 360 kg(N)·hm^-2, 144 kg(P₂O₅)·hm^-2, 360 kg(K₂O)·hm^-2), and CK (no fertilizer application)] and two varieties (newly developed ('SC5') and conventional ('SC205')] was carried out. Results showed that cassava root yield had significant positive correlation (P < 0.01) with N content at TRF, TRG and TRB stages, and with K₂O content at SS, TRG and TRB stages. Starch content of cassava root had significant positive correlation (P < 0.01) with N content at TRF stage. It had significant negative correlation (P < 0.01) with P₂O₅ content at SS and MS stages, and with K₂O content at MS stage. Application of nitrogen fertilizer significantly improved N content of cassava. However, phosphate and potassium fertilizers had little impact on N content. Phosphate fertilizer only significantly improved P₂O₅ content at SS stage while nitrogen and potassium fertilizer also enhanced P₂O₅ content. The application of potassium fertilizer significantly increased K₂O content of cassava, whereas nitrogen and phosphate fertilizers had no effect on K₂O content. The effects of nitrogen and phosphate fertilizers on N and P2O5 contents of 'SC205' were similar to those of 'SC5'. However, potassium fertilizer improved K₂O content of 'SC205' more than that of 'SC5'. While N and P₂O₅ contents of 'SC205' were very close to that of 'SC5', N content of 'SC205' at TRF stage was significantly higher than that of 'SC5'. Also P₂O₅ content of 'SC205' was significantly lower than that of 'SC5'.K₂O content of 'SC5' was higher than that of 'SC205' at SS to TRB stages and the difference was notable at TRF and TRG stages. It was concluded that N, P₂O₅ and K₂O contents of different cassava varieties were different, which significantly influenced cassava yield. Therefore to fertilize cassava, it was necessary consider not only nitrogen, phosphate and potassium fertilizer balance but also the nutritive characteristics of different cassava varieties.