Growth and yield of sweet potato in response to the application of nitrogen rates and paclobutrazol

Ribeiro, Nathalia Pereira; Fernandes, Adalton Mazetti; Silva, Rudieli Machado da; Pelvine, Raíra Andrade; Assunção, Natália Silva

doi:10.1590/1678-4499.20200447

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Article • Bragantia 80 • 2021 • https://doi.org/10.1590/1678-4499.20200447 copy

Growth and yield of sweet potato in response to the application of nitrogen rates and paclobutrazol

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The excess of nitrogen (N) causes the overgrowth of sweet potato foliage, increasing the self-shading and reducing the root yield. Therefore, a combined N and paclobutrazol (PBZ) application can reduce the vegetative overgrowth and benefit the sweet potato yield. The purpose of this study was to evaluate the plant growth, yield, uptake and removal of N by sweet potato plants fertilized with N and treated with PBZ during two planting seasons. The treatments consisted of four N rates (0, 50, 100 and 200 kg·ha^–1), three forms of PBZ application (PBZ-10: PBZ applied at 10 days after side-dressing N fertilization [DASNF]; PBZ-25: PBZ applied at 25 DASNF, and PBZ-10 + 25: PBZ applied at 10 plus 25 DASNF), and a control (without PBZ application). Paclobutrazol application temporarily reduced the length of the main branches of sweet potato planted in the rainy season, but it did not reduce the shoot biomass of plants in both planting seasons. A single application of PBZ at 10 DASNF increased the yield of fresh storage roots in the two planting seasons, but, during the rainy season, the increases were greater when two applications were carried out. The application of 50 kg·ha^–1 N in the rainy season was sufficient to reach the maximum yield of fresh storage roots, but, in the dry season, the N fertilization increased the N uptake without benefiting the root yield.

Key words
nitrogen uptake; triazole; gibberellin inhibitor; planting seasons; Ipomoea batatas (L)

Variables	Time of PBZ application⁽¹⁾ (1) Control = without PBZ application, PBZ-10 = application of 100 g·ha–1 PBZ at 10 DASNF, PBZ-25 = application of 100 g·ha–1 PBZ at 25 DASNF, PBZ-10 + 25 = application of 100 g·ha–1 PBZ at 10 plus 25 DASNF.				ANOVA (P > F)
	Control	PBZ-10	PBZ-25	PBZ-10 + 25	PBZ	N rate	PBZ × N
	Rainy season planting at 1^st evaluation
Number of main branches per plant (No.)	1.4a	1.6a	1.4a	1.4a	ns	ns	ns
Length of main branches (cm)	55.7ab	51.1c	57.3a	54.7b	< 0.001	< 0.001	ns
Number of secondary branches per plant (No.)	5.2b	5.3b	5.4ab	5.8a	0.039	< 0.001	ns
Number of leaves per plant (No.)	100.0a	97.8a	98.5a	102.4a	ns	< 0.001	ns
	Rainy season planting at 2^nd evaluation
Number of main branches per plant (No.)	1.4a	1.5a	1.3a	1.4a	ns	ns	ns
Length of main branches (cm)	81.6a	81.2a	81.0a	80.4a	ns	< 0.001	< 0.001
Number of secondary branches per plant (No.)	6.0b	6.2b	6.9a	7.0a	< 0.001	< 0.001	ns
Number of leaves per plant (No.)	136.7b	157.4a	141.3b	166.4a	< 0.001	< 0.001	ns
	Dry season planting at 1^st evaluation
Number of main branches per plant (No.)	1.3a	1.2a	1.2a	1.3a	ns	ns	ns
Length of main branches (cm)	53.4b	58.4a	58.2a	56.8a	< 0.001	ns	ns
Number of secondary branches per plant (No.)	4.2c	4.4c	4.8b	5.2a	0.044	< 0.001	ns
Number of leaves per plant (No.)	118.1c	142.3a	135.4b	146.4a	0.042	0.007	ns
	Dry season planting at 2^nd evaluation
Number of main branches per plant (No.)	1.3a	1.3a	1.2a	1.3a	ns	ns	ns
Length of main branches (cm)	78.6b	87.5a	86.3a	82.9ab	< 0.001	ns	ns
Number of secondary branches per plant (No.)	6.9b	7.3b	8.3a	8.5a	0.006	ns	ns
Number of leaves per plant (No.)	194.3d	216.9c	226.9b	237.6a	< 0.001	< 0.001	ns

Variables	Time of PBZ application⁽¹⁾ (1) Control = without PBZ application, PBZ-10 = application of 100 g·ha–1 PBZ at 10 DASNF, PBZ-25 = application of 100 g·ha–1 PBZ at 25 DASNF, PBZ-10 + 25 = application of 100 g·ha–1 PBZ at 10 plus 25 DASNF.				ANOVA (P > F)
	Control	PBZ-10	PBZ-25	PBZ-10 + 25	PBZ	N rate	PBZ × N
	Rainy season planting
Final plant population (plants·ha^–1)	23,675	24,408	24,387	24,975	ns	ns	ns
Shoot DM yield (kg·ha^–1)	1748b	1997a	1732b	2183a	< 0.001	< 0.001	ns
Storage root DM yield (kg·ha^–1)	3425b	4040a	3551b	4071a	< 0.001	< 0.001	ns
Whole plant DM yield (kg·ha^–1)	5174b	6037a	5284b	6254a	< 0.001	< 0.001	ns
Harvest index	0.68	0.67	0.70	0.68	ns	ns	ns
Fresh storage root yield (kg·ha^–1)	14,542c	16,676b	14,943c	17,361a	0.004	0.006	ns
Shoot N concentration (g·kg^–1)	17.0a	16.6ab	17.3a	15.7b	0.024	< 0.001	ns
Storage root N concentration (g·kg^–1)	5.0	5.2	4.6	4.3	ns	< 0.001	ns
N uptake (kg·ha^–1)	46.9b	54.3a	46.9b	52.7ab	0.02	< 0.001	ns
N removal (kg·ha^–1)	17.4b	21.4a	16.6b	17.3b	0.01	< 0.001	ns
	Dry season planting
Final plant population (plants·ha^–1)	11,417	12,098	11,851	11,193	ns	< 0.001	ns
Shoot DM yield (kg·ha^–1)	4447c	4556c	4972b	5314a	< 0.001	< 0.001	ns
Storage root DM yield (kg·ha^–1)	2469ab	2587a	2291b	2304b	< 0.001	< 0.001	ns
Whole plant DM yield (kg·ha^–1)	6917b	7144b	7264ab	7619a	< 0.001	< 0.001	ns
Harvest index	0.35a	0.36a	0.31b	0.30b	< 0.001	< 0.001	ns
Fresh storage root yield (kg·ha^–1)	10,180b	10,700a	9,271c	9,303c	< 0.001	< 0.001	ns
Shoot N concentration (g·kg^–1)	17.2	17.8	18.4	18.7	ns	0.007	ns
Storage root N concentration (g·kg^–1)	8.0	8.2	7.3	8.0	ns	< 0.001	ns
N uptake (kg·ha^–1)	94b	101b	107b	117a	< 0.001	< 0.001	ns
N removal (kg·ha^–1)	17.7	20.0	15.5	17.7	ns	< 0.001	ns

Instituto Agronômico de Campinas Avenida Barão de Itapura, 1481, 13020-902, Tel.: +55 19 2137-0653, Fax: +55 19 2137-0666 - Campinas - SP - Brazil
E-mail: bragantia@iac.sp.gov.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *Corresponding author: adalton.fernandes@unesp.br