<b>RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO</b>

ARAÚJO, ALANA CRISTINA FERREIRA; MADALÃO, JOÃO CARLOS; JAKELAITIS, ADRIANO; COSTA, ALAN CARLOS; ALMEIDA, GABRIEL MARTINS

doi:10.1590/1983-21252018v31n102rc

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Agronomia • Rev. Caatinga 31 (01) • Jan-Mar 2018 • https://doi.org/10.1590/1983-21252018v31n102rc copy

RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO ¹ 1 Paper extracted from the scientific initiation work of the first author.

RESÍDUOS DE ESPÉCIES FORRAGEIRAS AFETAM CARACTERÍSTICAS FOTOSSINTÉTICAS DO PEQUIZEIRO

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Some forages release allelopathic substances into the environment, and may prevent consortium with arboreal species in pastures. The objective of this work was to evaluate photosynthetic characteristics of pequizeiro plants (hereafter pequi) influenced by concentrations of residues of the forage species Urocholoa decumbens, Melinis minutiflora and Paspalum notatum. The treatments consisted of pequi cultivation under aerial residues of the three forage species mixed to the substrate in four concentrations (1, 2, 3 and 4% mass/mass), plus an additional treatment (comparative control) with pequi cultivated on the substrate without waste. The following parameters were evaluated: photosynthetic rate, stomatal conductance, transpiration rate, relationship between internal and external CO₂ concentration (Ci/Ca), maximum quantum yield, effective quantum yield of FS II, electron transport rate, nonchemical quenching and chlorophyll index, concerning the content of chlorophyll a, b and total in pequi plants at 50 and 100 days after transplanting (DAT), and the relative production of dry matter at 100 DAT. At 50 DAT, the following photosynthetic variables were affected in pequi plants: A, gs, chlorophyll a, chlorophyll b and total chlorophyll when cultivated in the presence of forage residues. At 100 DAT, the following photosynthetic variables were affected in pequi plants: A, Fv/Fm, ETR, NPQ, chlorophyll a, chlorophyll b and total chlorophyll, when cultivated in the presence of forage residues. Pequi plants had reduced relative dry matter yield when grown in the presence of U. decumbens. This variable was also affected when pequi was grown in increasing concentrations of residues of the species U. decumbens, M. minutiflora and P. notatum.

Keywords:
Allelopathy; Melinis minutiflora; Paspalum notatum; Photosynthetic rate; Urocholoa decumbens

Nutrients		Forage species
	URODE	MELMI	PASNO
N (g kg^-1)	5.60	5.60	14.00
P (g kg^-1)	2.50	2.70	2.70
K (g kg^-1)	20.00	12.00	13.50
Ca (g kg^-1)	2.60	2.70	2.90
Mg (g kg^-1)	2.50	1.70	2.00
S (g kg^-1)	0.80	1.00	1.30
B (mg kg^-1)	27.34	35.08	45.41
Cu (mg kg^-1)	1.78	2.77	5.99
Fe (mg kg^-1)	460.01	759.35	1461.48
Mn (mg kg^-1)	55.92	92.93	40.23
Zn (mg kg^-1)	19.87	25.19	14.66

Variables	URODE	MELMI	PASNO	TEST	CV%	F_A	F_B	F_AxB	F_{fatxadditional}
				50 DAT
A (μmol m^-2 s^-1)	4.32 b (-)	5.25 b (-)	8.58 a	9.21	36.45	10.82*	3.68*	1.36^ns	14.24*
g_s (mol m^-2 s^-1)	0.14 a (-)	0.15 a (-)	0.17 a	0.25	44.31	0.45^ns	0.85^ns	0.63^ns	12.71*
E (mmol m^-2 s^-1)	2.01 a	1.98 a	2.12 a	2.85	39.14	0.09^ns	1.14^ns	0.43^ns	8.79*
Ci/Ca	0.85 a	0.83 a	0.74 b	0.80	9.43	7.94*	1.83^ns	0.54^ns	0.89^ns
Fv/Fm	0.74 a	0.76 a	0.76 a	0.79	5.98	0.60^ns	1.76^ns	2.04^ns	3.68^ns
ΔF/Fm’	0.23 b	0.24 b	0.30 a	0.35	18.95	10.52*	2.69^ns	2.07^ns	26.59*
ETR	89.38 b	101.79 ab	119.15 a	141.36	19.97	7.81*	2.84^ns	2.02^ns	21.83*
NPQ	1.62 a	1.42 b	1.41 b	1.88	32.70	4.91*	0.62^ns	1.21^ns	0.36^ns
Chlorophyll a	241.50 b (-)	260.19 ab (-)	287.56 a	317.37	12.30	7.84*	6.52*	0.83^ns	19.83*
Chlorophyll b	62.06 b (-)	64.56 b (-)	89.94 a (-)	121.50	29.35	7.65*	7.05*	2.49^ns	19.05*
Chlorophyll total	303.56 b (-)	324.75 b (-)	377.50 b (-)	438.87	15.03	8.69*	7.70*	0.75^ns	17.79*
Variables				100 DAT
A (μmol m^-2 s^-1)	6.10 a (-)	4.72 a (-)	5.42 a (-)	8.56	53.42	1.58^ns	34.91*	2.39^ns	8.94*
g_s (mol m^-2 s^-1)	0.10 a	0.11 a	0.08 a	0.12	50.63	1.15^ns	8.93*	1.49^ns	2.37^ns
E (mmol m^-2 s^-1)	1.20 a	1.47 a	1.00 a	1.58	49.08	1.71^ns	8.41*	1.33^ns	2.38^ns
Ci/Ca	0.47 b	0.77 a (+)	0.43 b	0.56	29.26	14.51*	11.12*	1.91^ns	1.22^ns
Fv/Fm	0.51 b (-)	0.68 a (-)	0.59 b (-)	0.78	28.25	3.70*	14.60*	2.13^ns	3.60^ns
ΔF/Fm’	0.18 b	0.17 b	0.23 a	0.33	29.04	3.72*	27.77*	2.17^ns	20.02*
ETR	72.07 a (-)	65.98 a (-)	89.96 a (-)	130.05	29.30	2.29^ns	29.34*	1.68^ns	22.73*
NPQ	0.93 ab	1.49 a (+)	0.65 b (-)	0.96	51.86	7.69*	3.50*	2.84^ns	0.17^ns
Chlorophyll a	179.00 a (-)	249.58 a (-)	216.67 a (-)	318.33	33.31	2.66^ns	10.42*	2.14^ns	7.91*
Chlorophyll b	55.58 a (-)	65.33 a (-)	76.33 a (-)	141.50	44.65	1.15^ns	9.39*	1.52^ns	25.53*
Chlorophyll total	234.58 a (-)	314.92 a (-)	293.00 a (-)	459.83	34.67	1.91^ns	10.69*	2.04^ns	15.53*
RPDM (%)	77.83 b (-)	84.03 ab	90.37 a	100.00	12.13	5.87*	17.27*	2.02^ns	9.23*

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[1] ^*Corresponding autor: joaocmad@gmail.com.

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RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO 1 1 Paper extracted from the scientific initiation work of the first author.

RESÍDUOS DE ESPÉCIES FORRAGEIRAS AFETAM CARACTERÍSTICAS FOTOSSINTÉTICAS DO PEQUIZEIRO

ABSTRACT

RESIDUES OF FORAGE SPECIES AFFECT PHOTOSYNTHETIC CHARACTERISTICS OF THE PEQUIZEIRO ¹ 1 Paper extracted from the scientific initiation work of the first author.