Nitrogen and Potassium Fertilisation Influences Growth, Rhizosphere Carboxylate Exudation and Mycorrhizal Colonisation in Temperate Perennial Pasture Grasses

Abstract

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.

Effect of Forage Plant Mixture and Biostimulants Application on the Yield, Changes of Botanical Composition, and Microbiological Soil Activity

“…Firstly, fertilization, especially with nitrogen, promoted development of nitrophilous, highly competitive grass species. This phenomenon has been described by other authors [63,64]. The most abundant grass species in LGM were Lolium perenne and Festuca arundinacea (Figure 2).…”

Selection of Drought-Tolerant Pasture Species under Varying Soil and Moisture Conditions in Bauchi State, Nigeria

“…This is in agreement with previous results, which reported that N, Av. P, and K significantly influence shoot and root development (Lasheen et al, 2021, Tshewang et al, 2020and Song et al, 2010.…”

Microbial consortium inoculant increases pasture grasses yield in low‐phosphorus soil by influencing root morphology, rhizosphere carboxylate exudation and mycorrhizal colonisation

“…62,63 A potential stimulatory role of microbial inoculants in plant growth is to increase the concentration of rhizosphere carboxylates that enhance the availability of sparingly soluble nutrients, such as P. 6,56 In our study, malate and citrate were the major carboxylates found in the rhizosphere in both growth periods, consistent with the other reports. 44,[64][65][66][67] However, malate exudation was inconsistent between growth periods, which could be due to changes in the rhizosphere microbial community structure as . Effect of microbial consortium inoculant (MI) and rock mineral fertiliser (MF) on rhizosphere carboxylate (malate, acetate, trans-aconitate, citrate) exudation in three temperate perennial pasture grasses at 60 days after sowing (means ± SE).…”