Criteria for topdressing nitrogen application to common bean using chlorophyll meter

Maia, Suelen Cristina Mendonça; Soratto, Rogério Peres; Liebe, Suzane Maria; Almeida, Adriana Queiroz de

doi:10.1590/S0100-204X2017000700005

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CROP SCIENCE • Pesq. agropec. bras. 52 (07) • July 2017 • https://doi.org/10.1590/S0100-204X2017000700005 copy

Criteria for topdressing nitrogen application to common bean using chlorophyll meter

Critérios para a aplicação do nitrogênio em cobertura no feijoeiro comum com uso de clorofilômetro

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract:

The objective of this work was to establish the diagnostic leaf and the nitrogen sufficiency index (NSI) values most appropriate to estimate N requirement by the 'Pérola' common bean (Phaseolus vulgaris), based on chlorophyll meter monitoring. The diagnostic leaf was defined in an experiment with five N rates, and up to four sampling dates of the diagnostic leaves were evaluated (first, second, and third completely expanded leaves from the apex). The NSI was established in two crop seasons, under six N managements: M1, 40 kg ha^-1 N at sowing + 80 kg ha^-1 10 days after emergence (DAE) + 80 kg ha^-1 20 DAE (reference rate); M2, 20 kg ha^-1 at sowing + 40 kg ha^-1 10 DAE + 40 kg ha^-1 20 DAE (recommended rate); M3, 20 kg ha^-1 at sowing + 30 kg ha^-1 when NSI<96%; M4, 20 kg ha^-1 at sowing + 30 kg ha^-1 when NSI<93%; M5, 20 kg ha^-1 N at sowing + 30 kg ha^-1 when NSI<90%; and M6, without N application. The relative chlorophyll index readings on the second fully expanded leaf, at 21 DAE, and on the third leaf, at 28 and 35 DAE, are more precise to estimate the requirement of N by common bean. The NSI of 90% is more effective than the NSI of 93 or 96% for defining the moment for N topdressing application.

Index terms:
Phaseolus vulgaris; diagnostic leaf; nitrogen fertilization; nitrogen sufficiency index; nitrogen use efficiency; relative chlorophyll index

Embrapa Secretaria de Pesquisa e Desenvolvimento; Pesquisa Agropecuária Brasileira Caixa Postal 040315, 70770-901 Brasília DF Brazil, Tel. +55 61 3448-1813, Fax +55 61 3340-5483 - Brasília - DF - Brazil
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[TFN1] ⁽¹⁾M1, 40 kg ha^-1 N at sowing + 80 kg ha^-1 at 10 days after emergence (DAE) + 80 kg ha^-1 at 20 DAE (reference); M2, 20 kg ha^-1 at sowing + 40 kg ha^-1 at 10 DAE + 40 kg ha^-1 at 20 DAE (recommended rate); M3, 20 kg ha^-1 at sowing + 30 kg ha^-1 when NSI <96%; M4, 20 kg ha^-1 at sowing + 30 kg ha^-1 when NSI <93%; M5, 20 kg ha^-1 at sowing + 30 kg ha^-1 when NSI <90%; and M6, without application of N.

N treatment⁽¹⁾	Time of application (DAE)		Total N applied (kg ha^-1)
N treatment⁽¹⁾	Dry	Rainy	Dry	Rainy
M1	10 and 20	10 and 20	200	200
M2	10 and 20	10 and 20	100	100
M3	22	36	50	50
M4	22	36	50	50
M5	-	-	20	20
M6	-	-	0	0

Time	Leaf position	N rates (kg ha^-1)					CV (%)	Equation	R²	p-value
Time	Leaf position	0	50	100	150	200	CV (%)	Equation	R²	p-value
		Relative chlorophyll indexes (SPAD)
14 DAE	1^st	31.8	34.2	37.2	38.3	39.4	6.6	y = 32.30 + 0.038x	0.95**	0.0041
21 DAE	1^st	34.2	36.2	34.9	39.0	42.3	3.5	y = 34.32 + 0.037x	0.96**	<0.0001
21 DAE	2^nd	40.3	41.3	41.6	43.1	48.4	4.1	y = 39.95 + 0.035x	0.80**	0.0003
28 DAE	1^st	33.8	36.8	37.0	36.2	36.8	2.8	y = 33.98 + 0.042x - 0.0001x²	0.85*	0.0048
	2^nd	42.5	45.4	44.9	45.3	46.5	1.9	y = 43.34 + 0.015x	0.72**	0.0004
	3^rd	45.2	47.7	48.5	49.5	51.3	3.2	y = 45.63 + 0.028x	0.96**	0.0015
35 DAE	1^st	37.8	37.6	39.0	39.5	40.5	2.3	y = 37.42 + 0.014x	0.91**	0.0039
	2^nd	42.8	31.2	42.2	42.8	43.7	1.7	y = 42.52 - 0.0195x + 0.0001x²	0.78**	0.0034
	3^rd	37.7	36.4	46.4	47.3	48.6	2.0	y = 47.60 - 0.0032x + 0.0001x²	0.97**	0.0180
		Leaf N content (g kg^-1)
14 DAE	1^st	40.6	45.8	47.7	49.2	52.7	5.0	y = 41.70 + 0.005x	0.95**	0.0002
21 DAE	1^st	44.9	48.5	49.0	50.6	50.8	2.4	y = 46.14 + 0.024x	0.76**	0.0001
21 DAE	2^nd	38.7	41.7	44.7	47.8	48.7	3.4	y = 39.08 + 0.052x	0.97**	<0.0001
28 DAE	1^st	50.5	50.8	51.5	52.4	53.3	2.4	y = 50.26 + 0.014x	0.98**	0.0365
	2^nd	49.3	51.3	52.1	52.0	52.2	3.5	ns	-	0.2086
	3^rd	41.4	52.4	44.6	46.0	45.4	4.3	y = 41.58 + 0.0236x	0.87**	0.0191
35 DAE	1^st	51.4	51.2	50.5	56.1	55.2	1.8	y = 51.09 - 0.033x + 0.0001x²	0.65*	<0.0001
	2^nd	42.8	42.7	41.8	44.4	48.7	2.9	y = 43.13 - 0.043x + 0.0004x²	0.96**	<0.0001
	3^rd	40.2	40.7	40.5	41.6	45.4	3.5	y = 40.55 - 0.022x + 0.0002x²	0.94*	0.0016
		Grain yield (kg ha^-1)
End of cycle		3,210	3,664	3,863	4,026	4,018	7.6	y = 3,360.80 + 3.95x	0.85**	0.0089

Leaf position	Variable	Leaf N content	Grain yield
	14 DAE
1^st	RCI	0.68**	0.44*
1^st	Leaf N content	-	0.72***
	21 DAE
1^st	RCI	0.79**	0.59**
1^st	Leaf N content	-	0.61**
2^nd	RCI	0.80**	0.48*
2^nd	Leaf N content	-	0.64**
	28 DAE
1^st	RCI	0.75**	0.61**
1^st	Leaf N content	-	ns
2^nd	RCI	0.80***	0.56*
2^nd	Leaf N content	-	ns
3^rd	RCI	0.89***	0.64**
3^rd	Leaf N content	-	ns
	35 DAE
1^st	RCI	0.72***	ns
1^st	Leaf N content	-	ns
2^nd	RCI	0.77***	ns
2^nd	Leaf N content	-	ns
3^rd	RCI	0.81***	ns
3^rd	Leaf N content	-	ns

N treatment⁽²⁾	Shoot DM (g plant^-1)		N content in shoot DM (g kg^-1)		N accumulated in the shoot (kg ha^-1)		Grain yield (kg ha^-1)
N treatment⁽²⁾	Dry	Rainy	Dry	Rainy	Dry	Rainy	Dry	Rainy
M1	13.8a	15.7a	34.3ab	31.4a	88.8a	131.1a	3,120a	3,568a
M2	13.5a	13.1bc	34.1ab	28.4a	85.4a	103.4ab	2,959a	3,083a
M3	11.3ab	12.4c	36.1a	31.6a	76.4ab	106.5ab	2,740a	2,989a
M4	10.1bc	11.3c	28.0b	33.1a	47.0c	97.6b	2,796a	2,987a
M5	9.1bc	15.1ab	35.0ab	27.9a	60.9bc	117.3ab	2,676a	3,088a
M6	8.7c	11.3c	29.3ab	30.4a	46.8c	93.5b	2,813a	3,270a
CV (%)	11.3	7.4	10.6	5.3	15.4	13.1	10.5	12.5