PERIODICITY OF EXPOSURE OF HYDROPONIC LETTUCE PLANTS TO NUTRIENT SOLUTION<sup>1</sup>

DALASTRA, CLEITON; TEIXEIRA FILHO, MARCELO CARVALHO MINHOTO; VARGAS, PABLO FORLAN

doi:10.1590/1983-21252020v33n109rc

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Agronomy • Rev. Caatinga 33 (1) • Jan-Mar 2020 • https://doi.org/10.1590/1983-21252020v33n109rc copy

PERIODICITY OF EXPOSURE OF HYDROPONIC LETTUCE PLANTS TO NUTRIENT SOLUTION¹

PERIODICIDADE DE EXPOSIÇÃO DA ALFACE AMERICANA À SOLUÇÃO HIDROPÔNICA

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

A balanced periodicity of the nutrient solution flow is essential for better agronomic performances and low production costs in hydroponic systems. Thus, the objective of this work was to evaluate the effect of periodicity of exposure of lettuce plants to the nutrient solution in an NFT hydroponic system on the production, nutrition, and profitability of this crop. The experiment was conducted in a randomized block design with five replications. The treatments consisted of four periodicities of exposure of lettuce plants to the nutrient solution, consisting of intervals of 60, 30, and 15 minutes between pumping periods of 15 minutes; and uninterrupted flow of the nutrient solution. The plants were harvested at 30 days after transplanting, and 15 lettuce plants of each experimental plot were used to determine total fresh weight; root fresh weight; shoot freshweight; and contents of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn, and Zn in shoots, roots, and in the diagnostic leaf; accumulation of these nutrients in shoots and roots; and nitrate and ammonium contents in plant shoot. The highest production and profitability of lettuce were found using uninterrupted nutrient solution flow, which provided higher shoot and root nutrient contents to plants, and resulted in a better nutrient use efficiency.

Keywords:
Lactuca sativa L; Leaf nutrient concentration; Diagnostic leaf; Profitability; NFT hydroponic system; Intermittent flow of nutrient solution

		15/60 minutes	15/30 minutes	15/15 minutes	UF
		Leaf content	Leaf content	Leaf content	Leaf content
N	g kg^-1	32.67 A	38.33 A	41.3 A	40.93 A
P		5.13 A	5.97 A	6.70 A	6.83 A
K		36.27 L	41.17 L	42.73 L	50.9 A
Ca		6.2 L	8.57 L	7.87 L	15.3 A
Mg		3.23 L	4.57 A	4.43 A	6.43 H
S		1.77 A	2.10 A	2.37 A	2.17 A
B	mg kg^-1	39.67 A	40.00 A	42.67 A	43.00 A
Cu		13.33 A	15.00 A	23.33 H	23.33 H
Fe		194.33 H	223.33 H	198.33 H	327.67 H
Mn		65.67 A	94.67 A	100.33 A	173.67 H
Zn		69.00 A	108.00 H	117.33 H	215.00 H

	15/60	15/30	15/15	UF	15/60	16/30	15/15	UF
	Content in plant shoot system (g kg^-1)				Accumulation in plant shoot system (g plant^-1)
N	37.87a	39.07a	37.67a	37.33a	0.15b	0.11c	0.14B	0.25a
NO₃^-	0.49a	0.68a	0.24b	0.007c	0.002a	0.002a	0.001B	0.0004c
NH₄⁺	0.76a	0.41b	0.68a	0.64a	0.003b	0.002c	0.002C	0.004a
P	6.13b	6.53b	7.60b	10.47a	0.03b	0.02b	0.03B	0.07a
K	66.60ab	74.60a	42.57b	41.47b	0.30a	0.21b	0.16C	0.28a
Ca	12.10b	16.57ab	14.97b	20.97a	0.05b	0.05b	0.06B	0.14a
Mg	6.90a	7.23a	7.10a	7.43a	0.03b	0.02b	0.03B	0.05a
S	2.37a	2.47a	2.37a	2.80a	0.01b	0.01b	0.01B	0.02a
	Content in plant shoot system (mg kg^-1)				Accumulation in plant shoot system (mg plant^-1)
B	38.33a	41.67a	49.00a	37.33a	0.17b	0.12c	0.18B	0.25a
Cu	21.67a	21.00a	26.00a	25.00a	0.10b	0.06c	0.10b	0.17a
Fe	520.67b	659.00a	562.00ab	566.67ab	2.35b	1.80c	2.12d	3.79a
Mn	116.00c	151.00b	152.00b	229.00a	0.52b	0.41b	0.58b	1.54a
Zn	108.33b	161.33ab	213.33ab	274.67a	0.49c	0.44c	0.83b	1.84a
	Content in plant root system (g kg^-1)				Accumulation in plant root system (g plant^-1)
N	45.00a	44.60a	47.23a	46.90a	0.054b	0.039b	0.057a	0.072a
P	14.90b	17.33ab	16.96ab	19.40a	0.018b	0.015c	0.020b	0.030a
K	23.86a	21.56a	25.03a	24.76a	0.029b	0.019c	0.030b	0.038a
Ca	6.30a	5.16b	5.30b	5.33a	0.008a	0.005b	0.006b	0.008a
Mg	2.36a	2.06a	2.10a	2.03a	0.003b	0.002b	0.003b	0.003a
S	9.70a	11.16a	10.10a	10.23a	0.012b	0.010b	0.012b	0.016a
	Content in plant root system (mg kg^-1)				Accumulation in plant root system (mg plant^-1)
B	19.33a	25.66a	28.33a	26.66a	0.023b	0.022b	0.036a	0.041a
Cu	186.66b	220.66b	224.33b	286.00a	0.226c	0.193c	0.270b	0.438a
Fe	6768.00c	1047.00b	7864.00bc	14507a	8.166b	9.171b	9.471b	22.19a
Mn	97.00a	105.33a	105.33a	109.33a	0.117b	0.092c	0.128b	0.168a
Zn	221.33a	223.00a	199.66a	222.00a	0.268b	0.195c	0.241b	0.341a

	15/60¹ 1 15/60, 15/30, and 15/15 minutes = times of exposure of the plants to the nutrient solution (flow/absence of flow) applied through a rectangular 7 meters long PVC tubes with 10% slope, at flow rate of 1 L per minute; UF = uninterrupted flow of nutrient solution.		15/30		15/15		UF
	BRL (R$)	%	BRL (R$)	%	BRL (R$)	%	BRL (R$)	%
Production cost (A)
Workforce² 2 Total workforce cost during the production cycle per plant;	0.26	42%	0.26	40%	0.26	37%	0.26	30%
Electrical energy³ 3 Total electrical energy consumption cost considering an increasing pumping capacity of the nutrition solution in the hydroponic system as the flows are decreased);	0.03	5%	0.07	11%	0.13	18%	0.26	30%
Fertilizer⁴ 4 Cost of the nutrient solution consumed during the production cycle;	0.08	14%	0.07	11%	0.08	11%	0.11	13%
Water⁵ 5 Cost of the water consumed during the production cycle;	0.03	5%	0.03	5%	0.03	4%	0.03	3%
Seedlings⁶ 6 Total cost of the lettuce seedlings grown in phenolic foam, including their maintenance in the nursery;	0.07	11%	0.07	11%	0.07	10%	0.07	8%
Pesticides⁷ 7 Cost of application of Difenoconazole and Kasugamycin;	0.04	7%	0.04	6%	0.04	6%	0.04	5%
Fixed costs of implementation	0.10	16%	0.10	16%	0.10	14%	0.10	11%
Subtotal	0.61		0.64		0.71		0.87
Gross revenue (B)
Number of plants per bunch⁹ 9 Quantity of plants needed to compose a commercial bunch to be sold to wholesalers at a price of BRL (R$) 2.50.	3	33%	4	25%	3	33%	1	100%
Subtotal	0.83		0.63		0.83		2.50
Net revenue (A - B)
	0.22		-0.01		0.12		1.63
Cost'benefit analysis	136%		97%		118%		287%

Universidade Federal Rural do Semi-Árido Avenida Francisco Mota, número 572, Bairro Presidente Costa e Silva, Cep: 5962-5900, Telefone: 55 (84) 3317-8297 - Mossoró - RN - Brazil
E-mail: caatinga@ufersa.edu.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author

Brasil

Brasil

PERIODICITY OF EXPOSURE OF HYDROPONIC LETTUCE PLANTS TO NUTRIENT SOLUTION1

PERIODICIDADE DE EXPOSIÇÃO DA ALFACE AMERICANA À SOLUÇÃO HIDROPÔNICA

ABSTRACT

PERIODICITY OF EXPOSURE OF HYDROPONIC LETTUCE PLANTS TO NUTRIENT SOLUTION¹