不同土壤条件下外源施硒对紫甘薯硒含量及其产量的影响

Effects of exogenous selenium application on selenium content and yield of purple sweet potato under different soil conditions

【目的】探索不同紫甘薯品种对不同土壤条件下外源硒肥的吸收利用特点,为广西富硒甘薯产业良种良法配套提供参考依据。【方法】以桂经薯8号、桂经薯9号和越南紫薯3个紫甘薯品种为试验材料,选取南宁、北海等地的不同土壤类型(黏壤土、砂壤土)、不同土壤硒含量地块(中硒土壤、富硒土壤),采用小区比对方法,黏壤土设0(CK)、3000和6000g/ha3个硒肥用量处理,砂壤土设0(CK)、6000和12000g/ha3个硒肥用量处理,分别在甘薯栽植后30和60d进行叶面硒肥喷施,收获后测定鲜薯产量和块根硒含量。【结果】在富硒黏壤土条件下,3个甘薯品种的鲜薯产量在不同硒肥用量处理间无显著差异(P>0.05,下同),但其鲜薯硒含量均随硒肥用量的增加而升高,在硒肥用量为6000g/ha时,各品种均达广西富硒农产品标准DB45/T1061—2014《富硒农产品硒含量分类要求》的薯类富硒标准(0.02~0.20mg/kg);随硒肥用量增加,3个紫甘薯品种块根的硒富集系数(BCF)和硒吸收利用率均呈上升趋势。在砂壤土条件下,不同地点不同紫甘薯品种2个施硒处理的鲜薯产量均高于CK,但当硒肥用量从6000g/ha增加到12000g/ha时,合浦冲口的桂经薯8号、合浦禁山的越南紫薯及合浦白沙3个品种的鲜薯产量均出现降低趋势;随硒肥用量增加,甘薯块根BCF呈上升趋势,且处理间差异达显著水平;硒肥用量增加可提高多数试验点甘薯块根的硒吸收利用率,少数试验点甘薯块根的硒肥利用率出现降低趋势;在所有参试点中,在硒肥用量为6000g/ha时,3个参试紫甘薯品种的块根硒含量均达富硒标准;在合浦禁山点富硒土壤中,桂经薯8号在不施硒肥条件下,其块根硒含量可达0.038mg/kg,即天然富硒能力较强。【结论】桂经薯8号富硒能力较强,在富硒砂壤土地区可作为天然富硒甘薯品种进行大面积推广;桂经薯9号和越南紫薯也可在土壤硒含量中等以上的地区,辅助以叶面喷施6000g/ha的外源硒肥作为富硒甘薯品种进行推广。

【Objective】The aim of the study was to explore the absorption and utilization characteristics of exogenous selenium fertilizer by different purple sweet potato varieties under different soil conditions,and to provide reference for the matching of improved varieties and good methods in sweet potato industry in Guangxi.【Method】Taking Guijingshu 8,Guijingshu 9 and Vietnam purple potato as materials,different soil types(clay loam and sandy loam)and different selenium- content soils(medium selenium soil and selenium-rich soil)in Nanning and Beihai were selected and the plot comparison method was adopted. The clay loam was treated with 0(CK),3000 and 6000 g/ha selenium fertilizer,and the sandy loam was treated with 0(CK),6000 and 12000 g/ha selenium fertilizer. The leaves were sprayed with fertilizers 30 and 60 d after sweet potato planting,and the yield and selenium content of the tuberous roots were measured after harvest.【Result】Under the condition of selenium-rich clay loam,the yield of the three sweet potato varieties had no significant difference among different selenium fertilizer treatments(P>0.05,the same below),but the selenium content of the fresh tuberous roots increased with the increase of selenium fertilizer application. When the amount of selenium fertilizer was 6000 g/ha,the selenium content of each variety reached the selenium content classification requirement of selenium-rich agricultural products in Guangxi DB 45/T 1061-2014 Classification Requirement of Selenium-rich Agricultural Products (tuber crop:0.02-0.20 mg/kg). The selenium enrichment factor(BCF)and the utilization rate of selenium in the tuberous roots of the three purple sweet potato varieties increased with the increase of the amount of the selenium fertilizer. Under the condition of sandy loam,the yield of sweet potato varieties in different places was higher than CK under two selenium fertilizer treatments,but when the amount of selenium fertilizer increased from 6000 g/ha to 12000 g/ha,the yield of Guijingshu 8 in Chongkou,Hepu,Vietnam purple potato in Jinshan,Hepu and the three varieties in Baisha decreased. With the increase of the amount of selenium fertilizer,BCF showed an increasing trend,and the difference among treatments reached a significant level. The increase in the amount of selenium fertilizer could improve the absorption and utilization of selenium at most test sites,but the utilization rate of selenium fertilizer decreased with the increase of the amount of selenium fertilizer at a few test sites. When the amount of selenium fertilizer was 6000 g/ha,the selenium content in tuberous roots of three purple sweet potato varieties reached the selenium-rich standard at all test sites. Under the condition of no application of selenium fertilizer,the selenium content of Guijingshu 8 could reach 0.038 mg/kg in Jinshan,Hepu. Its natural selenium-rich ability was strong.【Conclusion】With strong selenium-rich ability,Guijinshu 8 can be widely popularized as a natural selenium-rich sweet potato variety in selenium-rich sandy soil. Guijingshu 9 and Vietnam purple sweet potato can also be used in areas with medium selenium contents soil,which can be planted as selenium-rich sweet potato varieties combined with spraying exogenous selenium fertilizer(6000 g/ha)on leaf surface.