Bell, R.W.

Mann, S.

Nguyen, T.T.

English

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The	importance	of	Cu	supplied	at	or	before	pegging	for	seed	and	pod	yield	of	peanut	on	low	Cu	sand	Thinh	Thai	Nguyenab	,	Surender	Mannb	and	Richard	Bellb	aAgriculture	Science	Institute	of	South-central	Vietnam,	Qui	Nhon,	Vietnam	bSchool	of	Veterinary	and	Life	Sciences,	Murdoch	University,	Murdoch	WA	6150	(R.bell@murdoch.edu.au)		INTRODUCTION	Peanut	(Arachis	hypogaea	L.)	produces	pods	under	ground	after	the	pegs	formed	from	fertilized	flowers	penetrate	the	soil.	However,	the	mechanism	of	uptake	and	delivery	of	copper	(Cu)	into	pods	for	seed	development	is	still	unknown.	This	hampers	efforts	to	determine	the	optimum	method,	rate	and	 time	 of	 application	 of	 Cu	 for	 peanut	 production.	 This	 study	 aimed	 to	 determine:	 (i)	 whether	pods	by	themselves	could	absorb	Cu	from	soil	rather	than	rely	on	redistribution	of	Cu	absorbed	by	roots;	 and	 (ii)	 effectiveness	 of	 Cu	 addition	 into	 soil	 before	 sowing	 relative	 to	 foliar	 spraying	 at	flowering,	pegging	or	podding.	METHODS	A	 low	 Cu	 sand	 (DPTA	 Cu:	 0.17mg/kg)	 was	 collected	 from	 Lancelin,	 WA.	 Basal	 nutrients	 were	applied	as	 solutions	 to	10	kg	aliquots	of	 soil	 that	had	been	air-dried,	 seived	and	 throughly	mixed.	Basal	fertilizers	are	applied	at	the	following	rates	(mg/kg):	KH2PO4	 ,	90.7;	K2SO4,	174.3;	CaCl2.2H2O,	98.0;	 MnSO4.4H2O,	 14.7;	 MgSO4.7H2O,	 23.3;	 H3BO3,	 0.14;	 CoSO4.7H2O,	 0.4	 ;	 Na2MoO4.2H2O,	 0.2	[modified	from	Reuter	et	al.	(1982)].	All	nutrient	solutions	were	prepared	using	analytical	grade	salts	and	the	macronutrient	solutions	were	purified	in	dithizone	before	use	(Hewitt	1952).		The	glasshouse	experiment	was	conducted	using	peanut	cv.	Streeton	with	seven	Cu	treatments	each	with	four	replicates.	The	treatments	were:	T1:	Control	(no	Cu);	T2:	spraying	10	mg	Cu	(~39.1mg	CuSO4.5H2O)/L	 on	 leaves	 at	 start	 of	 flowering	 (30	DAS);	 T3:	 spraying	 10	mg	Cu/L	 on	 leaves	 at	 the	start	 of	 pegging	 (50	 days	 after	 sowing	 (DAS));	 T4:	 spraying	 10	mg	 Cu/L	 on	 leaves	 at	 the	 start	 of	podding	(70	DAS);	T5:	1.3	mg	CuSO4.5H2O	/kg	to	9	kg	of	soil	 in	the	root	zone	(and	none	to	the	peg	compartment)	;	T6:	1.3	mg	CuSO4.5H2O	/kg	to	1	kg	soil	in	the	peg	compartment	(and	none	to	the	soil	in	the	root	zone);	T7:	1.3	mgCuSO4.5H2O	/kg	to	soil	in	both	the	root	and	peg	zone	(mixed	to	all	10	kg	of	soil	before	sowing).	Triple	deionized	water	(TDW)	was	added	to	soil	to	reach	field	capacity	(13	%,	w/w)	and	was	maintained	daily.	RESULTS	AND	DISCUSSION	Application	of	Cu	to	the	root	zone	soil	produced	the	highest	number	of	pegs	(Table	1).	Spraying	Cu	at	 flowering	or	pegging	produced	similar	pod	number	to	Cu	applied	at	sowing	to	the	root	zone	soil.	By	contrast,	only	Cu	foliar	application	at	flowering	was	as	effective	in	producing	the	same	pod	weight	 as	 soil	 Cu	 application.	 Soil	 Cu	 application	 to	 the	 root	 zone	 and	pod	 zone	was	 required	 for	maximum	seed	weight.	Application	of	Cu	 to	 the	pod	zone	only	had	no	effect	on	peg	number,	pod	number	of	 the	weights	of	pods	and	seeds	 (Table	1).	Foliar	application	of	Cu	was	most	effective	at	flowering	and	pegging,	but	significantly	less	effective	if	delayed	to	podding	stage.	Copper	 concentration	 in	 the	 young	mature	 leaf	was	 around	 1.0	mg/kg	 in	 control	 soil,	which	 is	similar	 to	 where	 Cu	 was	 only	 applied	 in	 the	 pod	 compartment:	 both	 were	 Cu	 deficient	 (Nualsri	1977).	 By	 contrast,	 foliar	 spraying	 increased	Cu	 in	 leaf	 to	 approximatly	 2.0	mg/kg.	However,	 even	though	 applying	 Cu	 in	 soil	 increaed	 pod	 and	 seed	 weight,	 the	 concentration	 of	 Cu	 in	 the	 young	XVIII INTERNATIONAL PLANT NUTRITION COLLOQUIUM 19-24 AUGUST 2017 • COPENHAGEN | DENMARK www.ipnc2017.org482mature	leaf	was	1.4	mg/kg	which	was	not	signigicantly	different	to	the	control.	At	harvesting	time,	the	concentration	of	Cu	in	leaf	was	not	significantly	different	among	treatments	(data	not	shown).	Table.1.	Effect	of	Cu	application	methods	and	timing	on	plant	Cu	concnetrations,	yield	components	and	yield	of	peanut	Treatment	No	of	pegs/	plant	No	of	pods/	plant	Dry	pod	(g/	plant)	Dry	seed	weight	(g/	plant)	Cu	concentrat-ion	(mg/kg)	in	leaf	(podding	-77	DAS)	Cu	concentrat-ion	(mg/kg)	in	seed	(harvest	-135	DAS)	Control	 20.3	d	 12.8	c	 8.8	d	 6.3	d	 1.1	c	 1.6	e	Cu	spray	at	flowering	 29.3	bc	 21.3	ab	 12.5	ab	 9.0	b	 1.9	a	 2.5	cd	Cu	spray	at	pegging	 25.2	bcd	 18.0	abc	 11.8	bc	 8.3	bc	 1.8	a	 2.9	bc	Cu	spray	at	podding	 23.0	cd	 14.5	c	 9.0	d	 7.5	cd	 2.0	a	 3.8	a	Soil	Cu	application	to	roots	only		 32.0	ab	 22.0	a	 12.8	ab	 8.5	bc	1.6	b	 2.0	de				(i)	Soil	Cu	application	to	pod	only	 24.8	bcd	 15.8	bc	 9.5	cd	 6.8	d	1.0	c	 1.5	e					(ii)	Soil	Cu		application	to		root	+	pod	 37.3	a	 23.0	a	 14.0	a	 10.5	a	1.4	b	 3.5	ab	LSD(0.05)	 7.9	 5.6	 2.0	 1.3	 0.29	 0.75	(i) Both	in	soil	root	zone	and	pod	compartment	have	the	same	Cu	concentration	in	seed(ii) In	root	zone	(no	Cu	added),	Cu	concentration	of	seed	was	1.5	mg/kg;	In	the	pod	compartment	(Cuadded),	Cu	concentration	of	seed	was	2.0	mg/kgCONCLUSIONS	Application	of	 Cu	 at	 1.3	mg	CuSO4.5H2O/kg	 soil	 increased	peanut	 yield	 by	 67	%	on	 the	 low	Cu	sand.	While	applying	Cu	via	foliar	spraying	improved	peanut	yield	on	deficient	soil	(increasing	peanut	yield	 by	 43	 %),	 its	 effectiveness	 was	 greatest	 at	 flowering	 and	 pegging	 and	 decreased	 with	 later	spraying	of	Cu.	Copper	application	 into	the	pod	compartment	had	no	effect	on	 leaf	Cu	or	pod	and	seed	weight	but	 it	did	 increase	Cu	concentration	in	seed	(data	not	shown).	 	This	suggests	that	pod	and	seed	development	of	peanut	depends	largely	on	Cu	re-translocation	from	the	root	uptake	of	Cu	rather	than	direct	absorption	from	the	soil	through	the	pod	wall.	Re-translocation	of	leaf-applied	Cu	can	also	boost	pod	and	seed	Cu	uptake	and	yield	provided	it	is	applied	by	the	time	of	early	pegging.	Further	 studies	 are	 needed	 on	 the	 mobility	 of	 Cu	 within	 peanut	 plants	 and	 its	 implications	 for	satisfying	pod/	seed	Cu	requirements.	ACKNOWLEDGEMENTS	We	 are	 grateful	 to	 ACIAR	 for	 their	 contribution	 to	 provide	 funding	 for	 this	 research.	We	 also	acknowledge	Dr	Graeme	Wright	from	the	Peanut	Company	of	Australia	for	supplying	seeds	and	the	rhizobium	culture		for	this	study.	REFERENCES	Hewitt,	E.J.	(1952)	Sand	and	water	culture	methods	used	in	the	study	of	plant	nutrition.		Reuter,	 D.J.,	 Loneragan,	 J.F.,	 Robson,	 A.D.	 and	 Plaskett,	 D.	 (1982)	 Zinc	 in	 subterranean	 clover	(Trifolium	subterraneum	L.	cv.	Seaton	Park).	I.	Effects	of	zinc	supply	on	distribution	of	zinc	and	dry	weight	among	plant	parts.		Australian	Journal	of	Agricultural	Research	33,	989	-	999.	Nualsri,	L.	(1997)	Copper	nutrition	in	peanut.	PhD	thesis.	University	of	West	Australia,	Perth.	XVIII INTERNATIONAL PLANT NUTRITION COLLOQUIUM 19-24 AUGUST 2017 • COPENHAGEN | DENMARK www.ipnc2017.org483

The importance of Cu supplied at or before pegging for seed and pod yield of peanut on low Cu sand

https://researchrepository.murdoch.edu.au/id/eprint/54219/1/Cu%20Sand.pdf

The importance of Cu supplied at or before pegging for seed and pod yield of peanut on low Cu sand

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