Effect of application form of nitrogen on oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum)

Abstract

Oxalate occurs naturally in forage species, but excess levels of soluble oxalate adversely affect their nutritional quality as animal feed. Although induction of oxalate in plants has been associated with nitrate application, relatively little is known about oxalate in forage grasses. In the present study, we investigated oxalate accumulation and mineral uptake by napiergrass (Pennisetum purpureum, cv. dwarf‐late) cultured in complete nutrient solution containing either solely nitrate or mainly ammonium as the main form of nitrogen. Total (shoot and root) yield of plants did not differ significantly between the nitrate and ammonium treatments. By contrast, the nitrogen form significantly affected oxalate accumulation and mineral uptake by plants. Nitrate application resulted in higher concentrations of soluble and insoluble oxalates in the shoot and soluble oxalate in the root than ammonium application. Nitrate application also resulted in higher concentrations of sodium and calcium in the shoot, and higher concentrations of sodium, calcium and magnesium in the root than ammonium application. The results suggest that the application of nitrate fertilizer as the sole source of nitrogen should be avoided in the cultivation of oxalate‐rich forages, though further studies are needed under field conditions.

How functional is a trait? Phosphorus mobilization through root exudates differs little between Carex species with and without specialized dauciform roots

“…Oxalate was the main carboxylate exuded by roots of all Carex species. This may be because the supply of N was mainly as nitrate in our experiment, as the accumulation of oxalate has been related to the activity of nitrate reductase (Tian et al ., ; Rahman et al ., ). Lower oxalate exudation in species with DRs are paralleled by a small release of oxalate by cluster roots and other roots of L. albus (Neumann & Römheld, ; Dessureault‐Rompré et al ., ).…”

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“…High oxalate concentrations occur, usually along with calcium oxalate, in some tropical grasses and particularly in their roots (see above; also Rahman et al, 2010). Experimental evidence shows that oxalate (and calcium oxalate) synthesis increases in plants including spinach, rice and Napier grass ( Pennesetum purpureum ) with high availability of nitrate, but not of ammonium (Hatcher et al, 1997a; Rahman et al, 2010).…”

“…, reported absence in shoots; S, reported presence in shoots (SS and SSS indicate more substantial concentrations); , reported absence in roots; R, reported presence in roots (RR and RRR indicate more substantial concentrations) . References: 1, Ellis, 1990; 2, Jackson et al, 1996; 3, Awika and Rooney, 2004; 4, Hodson et al, 2005; 5, Sangster, 1978; 6, Hodson and Sangster, 1989; 7, Parry and Kelso, 1977; 8,McNaughton et al, 1985; 9,Geis, 1978; 10, Parry and Kelso, 1975; 11, Schaller et al, 2013; 12, Rahman and Kawamura, 2011; 13, McKenzie, 2012; 14, Rahman et al, 2010; 15, Marais et al, 1997; 16, Clay, 1990; 17, Crawford et al, 2010; 18, Hennessy et al, 2016; 19, Patchett et al, 2008; 20, Ryley et al, 2007; 21, Kato-Noguchi and Peters, 2013; 22, Zuniga et al, 1983; 23, Barria et al, 1992; 24, Rice et al, 2005; 25, Copaja et al, 2006; 26, Lu et al, 2012; 27, Robert et al, 2012; 28, Singh et al, 2003; 29, Koulman et al, 2008; 30, Kaul and Vats, 1998; 31, Cheeke, 1995; 32, Iason et al, 1995; 33, Volz and Clausen, 2001 .…”

“…Little published work has quantified calcium oxalate in grass roots, but Rahman et al (2010) reported greater concentrations of soluble oxalate (discussed below) and similar concentrations of insoluble oxalate (calcium oxalate) in the shoots compared to the roots of Pennisetum purpureum . Raphides are concentrated in the root apical meristem in some other plants, apparently offering a defense against herbivores (e.g., Osuji, 2013).…”

“…Experimental evidence shows that oxalate (and calcium oxalate) synthesis increases in plants including spinach, rice and Napier grass ( Pennesetum purpureum ) with high availability of nitrate, but not of ammonium (Hatcher et al, 1997a; Rahman et al, 2010). …”