水分和氮源类型对小麦根际土壤酶活性和氮素利用效率的影响

本研究以‘郑麦366'(强筋)和‘百农207'(中筋)两个小麦品种为试验材料,分别在全生育期不灌水(W₁)和拔节+抽穗灌两水(W₂)条件下,研究了氯化铵(NT₁)、硝酸钙(NT₂)、尿素(NT₃)和硝酸铵钙(NT₄)4种氮源类型对小麦土壤供氮能力、产量和氮素利用效率的影响,以期为小麦高产高效生产提供理论和技术支撑。结果表明: 1)随着土层深度的增加,开花期土壤中铵态氮和硝态氮含量呈下降趋势。在W₂条件下,0～60 cm土层铵态氮、硝态氮含量,根际土壤脲酶、蔗糖酶和过氧化氢酶活性均低于相应W₁条件下,其中强筋小麦郑麦366平均分别下降10.0%、13.3%、7.5%、2.8%和3.9%。2)两个小麦品种0～60 cm土层铵态氮含量均表现为在NT₁和NT₃处理下显著高于其他处理;而硝态氮含量则在NT₂和NT₃处理下显著高于其他处理。与NT₁和NT₂处理相比,NT₃和NT₄提高了灌浆中、后期土壤脲酶和蔗糖酶活性。3)两个小麦品种在NT₃和NT₄处理下籽粒产量和氮素利用效率较高;其中在W₂条件下,郑麦366在NT₃和NT₄处理下的产量较NT₁处理分别增加14.9%和20.7%,NUE分别增加25.6%和13.9%。4)相关分析结果表明, 0～20 cm土壤硝态氮含量、20～40 cm土壤铵态氮含量分别与小麦产量、氮素利用效率呈显著正相关。两种水分条件下,施用尿素和硝酸铵钙均提高了灌浆中、后期根际土壤酶活性,有利于籽粒产量和氮素利用效率的提高。

Effects of water and nitrogen source types on soil enzyme activity and nitrogen utilization efficiency of wheat

To provide basis for high-yield and high-efficiency of wheat production, with two wheat cultivars, ‘Zhengmai 366' (strong gluten) and ‘Bainong 207' (medium gluten), we investigated the effects of four nitrogen source types, ammonium chloride (NT₁), calcium nitrate (NT₂), urea (NT₃) and calcium ammonium nitrate (NT₄), applied under two water treatments, no irrigation (W₁) and irrigation at jointing and heading stages (W₂), on soil N-supplying capacity, grain yield and nitrogen utilization efficiency. The results showed that content of soil ammonium and nitrate at flowering stage decreased with increasing soil depths. Compared with the corresponding value of ‘Zhengmai 366' under W₁ treatment, W₂ treatment decreased the contents of soil ammonium and nitrate in the 0-60 cm layer, and enzymes activities of urease, invertase and catalase by 10.0%, 13.3%, 7.5%, 2.8%, and 3.9%, respectively. For the two wheat cultivars, the content of ammo-nium was significantly higher under NT₁ and NT₃ treatments than that of others, while the content of nitrate under NT₂ and NT₃ treatments was significantly higher than that of others. Additionally, NT₃ and NT₄ treatments increased soil urease and invertase activities at the middle and later stages of grain filling. Compared with NT₁ treatment, NT₃ and NT₄ fertilization increased grain yield and nitrogen use efficiency of cultivar ‘Zhengmai 366' by 14.9% and 20.7%, 25.6% and 13.9%, under W₂ treatment, respectively. Soil nitrate content in the 0-20 cm layer and the ammonium content in the 20-40 cm layer were positively correlated with wheat grain yield and nitrogen utilization efficiency. Under both water conditions, applying urea and calcium ammonium nitrate improved soil enzyme activity at the middle and later stages of grain filling, which was beneficial for wheat yield and nitrogen use efficiency.