Contribui??o do sistema radicular pr?-formado na absor??o de nitrog?nio em mudas micropropagadas de abacaxizeiro cultivar "Vit?ria?

• Main Author: RIBEIRO, Dan?bia Gon?alves
• Other Authors: Ara?jo, Adelson Paulo de
• Format: Others
• Language: Portuguese
• Published: Universidade Federal Rural do Rio de Janeiro 2017
• Subjects: pineapple; root system; nitrogen fertilizer; abacaxi; Ananas comosus; sistema radicular; adubo nitrogenado; Produ??o Vegetal
• Online Access: https://tede.ufrrj.br/jspui/handle/jspui/1683

Submitted by Jorge Silva ([e-mail]) on 2017-05-23T19:32:21Z No. of bitstreams: 1 2010 - Dan?bia Gon?alves Ribeiro.pdf: 824606 bytes, checksum: dd284e46bd5222c0f71d865d8ad108b3 (MD5) === Made available in DSpace on 2017-05-23T19:32:21Z (GMT). No. of bitstreams: 1 2010 - Dan?bia Gon?alves Ribeiro.pdf: 824606 bytes, checksum: dd284e46bd5222c0f71d865d8ad108b3 (MD5) Previous issue date: 2010-02-23 === Information about the mineral nutrition of new varieties of pineapple (Ananas comosus), and about the nutrient absorption of the preformed root system of micropropagated plantlets, is lacking. This work had the objective to evaluate the contribution of the preformed roots of pineapple seedlings cultivar ?Vit?ria? in plant growth and nitrogen (N) absorption in the first months of acclimatization of the seedlings. A greenhouse experiment was conducted in the Department of Fitotecnia of UFRRJ, Serop?dica (RJ). The experimental design was randomized blocks in an incomplete factorial design, with three treatments of root pruning (without pruning, half pruning and total pruning), four times of N application (0, 30, 60 and 90 days after transplant ? DAT), four plant harvests at different growth stages (30, 60, 90 and 120 DAT), and five replications, summing 150 experimental units. The substrate was the A horizon of Planosol in 5 kg pots. At harvests, the shoot and root dry weight was measured. The root systems were scanned and their area and length determined by digital image analysis. Concentrations and content of N in shoots and roots, and the influx of N into roots, were determined. Plants without root pruning produced higher shoot mass at every harvest. The application of N at 0 or 30 DAT provided a larger shoot mass at 60 and 120 DAT. After 120 DAT, the plants that received root pruning had lower root mass, area and length, than those plants without pruning. Time of N application did not affect the mass, area or length of roots. The N application after 60 DAT caused higher biomass allocation to roots, increasing root:shoot ratio. Plants without root pruning showed higher specific root area and length at 30 and 60 DAT, hence thinner roots. Time of N application did not affected the N accumulation in shoots, but plants without root pruning and that received N at 0 and 30 DAT had a dilution effect of N, with lower shoot N concentration. Total root pruning provided lower N accumulation in plants. Influx of N per root area and root length was not affected by time of N application. Influx of N into roots was higher in plants that received root pruning, since they presented younger roots with higher absorption activity. It is concluded that the preformed root system of pineapple plantlets is able to absorb N during the first months after planting, and that the practice of pruning the root system, entirely or partially, leads to lower initial plant growth. === H? car?ncia de informa??es sobre a nutri??o mineral das novas variedades de abacaxi (Ananas comosus), bem como sobre o manejo do sistema radicular pr?-formado das mudas micropropagadas e sua efici?ncia na absor??o de nutrientes. Este trabalho teve como objetivo avaliar a contribui??o das ra?zes pr?-formadas em mudas micropropagadas de abacaxizeiro cultivar ?Vit?ria? no crescimento e absor??o de nitrog?nio (N) nos primeiros meses de aclimata??o das mudas. Foi conduzido um experimento em casa de vegeta??o no Departamento de Fitotecnia da UFRRJ, em Serop?dica (RJ). O delineamento experimental foi de blocos ao acaso em esquema fatorial incompleto, com tr?s tratamentos de poda de raiz (sem poda, meia poda e poda total), quatro ?pocas de aplica??o de N (aos 0, 30, 60 e 90 dias ap?s transplante ? DAT), quatro coletas em diferentes est?dios de crescimento (aos 30, 60, 90 e 120 DAT) e cinco repeti??es, totalizando 150 unidades experimentais. O substrato foi horizonte A de Planossolo em vasos de 5 kg. Nas coletas, foi mensurada a massa seca da parte a?rea e da raiz. Os sistemas radiculares foram digitalizados e sua ?rea e comprimento determinados por an?lise digital de imagens. Foram determinados os teores e conte?dos de N na parte a?rea e ra?zes, e o influxo de N nas ra?zes. As plantas sem poda de raiz produziram maior massa de parte a?rea em todas as ?pocas de avalia??o. A aplica??o do adubo nitrogenado aos 0 ou 30 DAT proporcionou maior massa de parte a?rea aos 60 e aos 120 DAT. Decorridos 120 DAT, as plantas que receberam poda de raiz apresentaram massa, ?rea e comprimento radicular inferiores ?s que n?o receberam. A ?poca de aplica??o do adubo nitrogenado n?o influenciou na massa, ?rea e comprimento radicular. A aplica??o do N ap?s 60 DAT causou maior aloca??o de biomassa nas ra?zes, aumentando a rela??o raiz:parte a?rea. As plantas sem poda de raiz apresentaram maior ?rea radicular espec?fica e comprimento radicular espec?fico aos 30 e 60 DAT, ou seja, ra?zes mais finas. A ?poca de aplica??o de N n?o modificou a acumula??o de N na parte a?rea, mas as plantas sem poda de raiz e com aplica??o de N aos 0 e 30 DAT apresentaram efeito de dilui??o do N, com menor teor de N na parte a?rea. A poda total proporcionou menor acumula??o de N nas plantas. O influxo de N por ?rea e por comprimento radicular n?o sofreu influ?ncia da ?poca de aplica??o de N. O influxo radicular de N foi maior nas plantas que receberam poda total, por apresentarem ra?zes mais novas, com maior atividade de absor??o. Pode-se concluir que o sistema radicular pr?-formado presente nas mudas micropropagadas de abacaxi se mostrou apto em absorver o N nos primeiros meses ap?s o plantio, e que a pr?tica da poda do sistema radicular, total ou parcial, acarreta menor desenvolvimento inicial das plantas.