不同氮素形态配比对菜用甘薯产量和品质的影响

菜用甘薯存在产量低、品质差以及在种植过程中由于不合理施肥造成生态环境恶化等问题,因此,针对以上问题开展本研究。氮肥作为农业肥料投入的主要部分,是影响菜用甘薯产量和品质的重要因素,通过设置不同氮素形态配比处理,根据菜用甘薯茎尖产量和品质相关指标的变化,揭示菜用甘薯产量和品质对氮素形态配比的响应机制,为提升菜用甘薯产量和品质的同时减轻因不合理施肥造成环境污染提供理论依据。本研究为大田试验,供试品种为生产上主栽的2个菜用甘薯品种‘福薯18’（F18）和‘鄂薯10号’（E10）,采用两因素裂区试验设计,设5个氮素形态配比处理为：（1）NH₄⁺-N∶NO₃^--N∶CONH₂-N =1∶1∶1 (N₁);（2）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶0∶2 (N₂);（3）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶0∶1 (N₃);（4）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2∶0 (N₄);（5）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶1∶0 (N₅)。研究结果表明,N₄和N₅处理均可显著提高菜用甘薯的茎尖产量、总酚含量、总黄酮含量、可溶性糖含量、苯丙氨酸解氨酶(PAL)酶活性和IbPAL基因表达量;同一时期不同处理间差异显著,随着生育期的不断推进,各项指标的变化呈先升后降的趋势,其中以N₄处理效果更为显著,除可溶性糖含量在N₃处理下最低外,其他各项指标均在N₂处理下最低,由相关性分析证实,总酚、总黄酮和可溶性含量及PAL酶活性与IbPAL基因表达量呈显著正相关,而可溶性糖含量与基因表达量呈负相关,表明可溶性糖含量的变化与IbPAL基因表达无相关性;由氮素形态配比处理可知,相对于N₂和N₃处理,N₄和N₅处理为植株提供了更多的NO₃^--N,由此推断NO₃^--N在菜用甘薯生长发育过程中起到更为重要的促进作用,而CONH₂-N在本研究中对甘薯产量和品质的促进作用并不突出。而N₄处理即NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2∶0的配肥方案是促进菜用甘薯产量和品质提升的最佳配施组合。本研究结果可为合理配肥以获得理想的作物产量和品质提供理论依据,为在其他作物上开展相关研究提供参考。

Effects of Different Forms and Ratios of Nitrogen on Yield and Quality of Leaf-vegetable Sweet Potato Stem Tips

This study was conducted to solve the problems of low yield, poor quality, and ecological environment deterioration caused by unreasonable fertilization in the planting process of leaf-vegetable sweet potato. As the main part of agricultural fertilizer input, nitrogen fertilizer is an important factor affecting the yield and quality of leaf-vegetable sweet potato. The response mechanism of yield and quality of leaf-vegetable sweet potato to nitrogen form ratio was revealed by setting different nitrogen form ratio treatments and according to the changes of related indexes of yield and quality of leaf-vegetable sweet potato stem tip. It provides a theoretical basis for reasonable fertilization to improve the yield and quality of leaf-vegetable sweet potato and reduce environmental pollution caused by unreasonable fertilization. This study was a field experiment. Two main leaf-vegetable sweet potato varieties, ‘Fushu 18’ and ‘Eshu 10’, were used. A field experiment with the two-factor split-plot experiment design with five treatments was conducted: (1) NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶1∶1 (N₁); (2) NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶0 ∶2 (N₂); (3) NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶0 ∶1 (N₃); (4) NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2 ∶0 (N₄); (5) NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶1∶0 (N₅). The results showed that N4 and N5 treatments significantly increased shoot tip yield, total phenol content, total flavonoids content, soluble sugar content, PAL activity and IbPAL gene expression of leaf-vegetable sweet potato. There were significant differences between different treatments in the same period. With the continuous progress of the growth period, the changes of various indicators showed a trend of increasing first and then decreasing. Among them, the effect of N₄ treatment was more significant. Except the soluble sugar content was the lowest under N₃ treatment, the other indicators were the lowest under N₂ treatment. The correlation analysis confirmed that total phenols, total flavonoids, soluble content and PAL enzyme activity were positively correlated with IbPAL gene expression, while the soluble sugar content was negatively correlated with gene expression, indicating that the change of soluble sugar content was not correlated with IbPAL gene expression. It can be seen from the treatment of nitrogen morphology ratio that N₄ and N₅ treatments provided more NO₃^--N for plants than N₂ and N₃ treatments, suggesting that NO₃^--N played a more important role in promoting the growth and development of leaf-vegetable sweet potato, but the effect of CONH₂-N on yield and quality of sweet potato was not prominent in this experiment. N₄ treatment (NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2∶0) was the best combination to promote the yield and quality of leaf-vegetable sweet potato. The results of this study could provide a theoretical basis for reasonable fertilization to obtain ideal crop yield and quality, and provide reference for related research on other crops.