施钾对木薯产量及钾养分吸收的影响

为探索施钾对木薯生长发育、钾含量、钾积累量及钾肥利用效率的影响,采用田间试验,以我国主栽品种SC205为材料,设K_2O用量0、120、240 kg/hm~2共3个水平,于不同生育期测定木薯叶片、茎秆、细根、块根的干物质量、钾含量,并在木薯收获期调查、测定农艺性状及块根鲜薯产量(FRY)。结果表明:(1)与不施钾相比,施钾显著提高木薯株高、叶面积、叶面积指数、叶绿素含量及鲜薯产量,增幅分别为16.1%~19.0%、3.8%~8.4%、12.8%~18.2%、13.6%~17.3%、12.8%~29.4%、9.9%~25.6%,其中,K_(120)处理产量最高,达27.1 t/hm~2;(2)施钾显著提高各组织钾含量及钾积累量,K_(120)和K_(240)处理间的钾积累量无显著差异;不同组织钾含量表现为叶片茎秆细根块根;随生育期推进,钾素积累的主要组织由叶片向茎秆和块根转变;(3)木薯钾肥效率、钾素生理效率、钾素利用效率、钾素收获指数均随施钾量增加而显著降低,100 kg鲜薯需钾量随施钾量增加显著提高。综合木薯产量、钾积累量、钾肥利用效率等指标综合分析,建议木薯施钾量为120 kg/hm~2。

Effects of Potassium Fertilization on Fresh Root Yield and Potassium Absorption of Cassava

Variety SC205 widely cultivated across South China was used as test material, a field experiment with three K₂ O rates, i.e. 0 (CK), 120 and 240 kg/hm² was conducted to investigate the effects of potassium fertilization on the growth, potassium contents and accumulations, potassium use efficiency of cassava. Dry matter and K contents of leaves, stems, fibrous roots and storage roots were measured in diffident growth stages of cassava, meanwhile, agronomic characters and fresh root yield (FRY) were measured at harvest stage of cassava. The results showed that, 1) compared with CK, K fertilization significantly improved the plant height, leaf area, leaf area index, chlorophyll content and FRY of cassava by 16.1%-19.0%, 3.8%-8.4%, 12.8%-18.2%, 13.6%-17.3%, 12.8%-29.4% and 9.9%-25.6%, respectively. FRY of K₂ O 120 kg/hm² was the highest (27.1 t/hm²). 2) K fertilization extremely significantly increased K contents and uptakes, but no significant difference in K uptakes of different organs between the treatments of K₂ O 120 kg/hm² and 240 kg/hm². K contents in various organs were an order of leaf > stem > fibrous root > storage root. With the growth of cassava, the main K uptake organ of cassava shifted from leaf to stem and fibrous root. 3) With the increment of K fertilization rate, K use efficiency, K physiology efficiency, K utilization efficiency and K harvest index of cassava decreased significantly while K absorption per 100 kg fresh storage root increased significantly. Based on FRY, K accumulation and K use efficiency, 120 kg/hm² of K₂ O fertilization is optimal for cassava.