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Nitrogen and Potassium Fertilisation Influences Growth, Rhizosphere Carboxylate Exudation and Mycorrhizal Colonisation in Temperate Perennial Pasture Grasses
Agronomy ( IF 3.949 ) Pub Date : 2020-11-27 , DOI: 10.3390/agronomy10121878
Sangay Tshewang , Zed Rengel , Kadambot H. M. Siddique , Zakaria M. Solaiman

Optimisation of potassium (K) use efficiency in pastures on sandy soil is challenging. We characterised growth response, root carboxylate exudation and mycorrhizal colonisation in three perennial pasture grasses: tall fescue (Festuca arundinacea L.), veldt grass (Ehrharta calycina Sm.) and tall wheatgrass (Thinopyrum ponticum L.) in two glasshouse experiments with: (1) four K rates (0, 40, 80 and 120 mg K kg‒1 soil), and (2) four N and K treatments (no N and K (–N–K), 81 mg N kg‒1 soil but no K, 80 mg K kg‒1 soil but no N, and N at 81 and K at 80 mg kg‒1 soil (+N+K)) in low-K sandy soil. Veldt grass had the highest shoot dry weight and shoot P content, but the lowest mycorrhizal colonisation. Potassium fertilisation had no significant impact on exudation of citrate and oxalate. The K0 plants had significantly lower exudation of acetate and total carboxylates than K40 plants. The +N+K plants had maximum shoot growth at both harvests (30 and 60 days after sowing (DAS)) and highest N and K shoot contents at 60 DAS. The –N–K plants exuded maximum amounts of citrate and malate at 30 DAS, but at 60 DAS tall fescue had the highest rhizosphere concentrations of citrate and malate in the +N+K treatment. At 60 DAS, mycorrhizal colonisation was significantly lower with than without N and K fertilisation. We concluded that pasture grasses could yield well even in inherently low-K soil without external K fertilisation and mycorrhizal symbiosis. However, the +N+K plants had the highest yield and root carboxylate exudation.

中文翻译:

氮和钾肥对温带多年生牧草生长,根际羧酸根分泌和菌根定殖的影响

在沙质土壤上的牧场中优化钾(K)的利用效率具有挑战性。在两个温室试验中,我们在以下三个温室试验中表征了三种多年生牧草的生长响应,根羧酸盐渗出和菌根定植:高羊茅(Festuca arundinacea L.),草皮草(Ehrharta calycina Sm。)和高麦草(Thinopyrum ponticum L.)。 1)四种钾肥(0、40、80和120 mg K kg ‒1土壤),和(2)四种氮和钾处理(无氮和钾(–N–K),81 mg N kg ‒1土壤,但无钾,80 mg K kg ‒1土壤,但无氮,N在81和80 mg kg kg ‒1下低钾沙质土壤中的土壤(+ N + K)。Veldt草的茎干重和P含量最高,但菌根定植率最低。钾肥对柠檬酸盐和草酸盐的渗出没有显着影响。与K40植物相比,K0植物具有显着更低的乙酸盐和总羧酸盐渗出。+ N + K植株在两个收获期(播种后30和60天(DAS))都具有最大的枝条生长,在60 DAS时具有最高的N和K枝条含量。–N–K植物在30 DAS时渗出最大量的柠檬酸和苹果酸,但在+60 + DAS时,+ N + K处理中最高的羊茅根际的柠檬酸和苹果酸浓度最高。在60 DAS时,与不施氮和钾相比,菌根定植率要低得多。我们得出的结论是,即使在本来就低钾的土壤中,没有外部钾肥和菌根共生的作用,牧草也能获得良好的收成。然而,+ N + K植物具有最高的产量和根部羧酸盐渗出。
更新日期:2020-11-27
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