NITROGEN SOURCES AND DOSES ON GROWTH AND QUALITY OF SEEDLINGS OF Cassia grandis AND Peltophorum dubium 1

Abstract

-The demand for seedlings of Brazilian native tree species has increased due to the growing number of recovery projects for degraded areas. In order to obtain success in the revegetation, high quality seedlings should be used. Among the factors that affect the quality of seedlings there is nitrogen fertilization, since nitrogen (N) is one of the nutrients required in the largest amount by plants. Thus, this study aimed to evaluate the response of Cassia grandis and Peltophorum dubium seedlings to N sources and doses. The treatments were represented by a factorial of three sources (ammonium nitrate, calcium nitrate and ammonium sulfate) by five N doses (0, 50, 100, 150 and 200 mg dm -3 ), arranged in randomized complete block design, with four replicates. After 145 days of sowing, were obtained: height (H), collar diameter (CD), shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), and calculated the dry matter mass ratio of shoot and root (SDM/RDM) and the Dickson Quality Index (DQI). Nitrogen fertilization resulted in growth gains and improved the seedlings quality of both species. However, the sources and the source × doses interaction were not significant for all variables. For the studied substrate (Red-Yellow Latosol) the recommended dose is 185 mg dm-3 of N for the production of Peltophorum dubium seedlings. For the production of Cassia grandis seedlings was not able to find the optimum dose of N.Keywords: Plants nutrition; Seedling production; Nitrogen fertilization. FONTES E DOSES DE NITROGÊNIO NO CRESCIMENTO E QUALIDADE DE MUDAS DE CASSIA GRANDIS E PELTOPHORUM DUBIUMRESUMO -A demanda por mudas de espécies nativas tem aumentado devido ao crescente número de projetos de recuperação de áreas degradadas. Para o sucesso da revegetação, devem ser utilizadas mudas de qualidade, e entre os fatores que influenciam a qualidade, destaca-se a fertilização nitrogenada, uma vez que o nitrogênio (N) é um dos nutrientes requeridos em maior quantidade pelas plantas. O objetivo deste estudo foi avaliar a resposta das mudas de Cassia grandis L. f. e Peltophorum dubium (Spreng.) Taub. às fontes e doses de N. Os tratamentos foram representados por um fatorial de três fontes (nitrato de amônio, nitrato de cálcio e sulfato de amônio) e cinco doses de N (0, 50, 100, 150 e 200 mg dm -3 ), dispostos no delineamento em blocos casualizados, com quatro repetições. Após 145 dias da semeadura, foram obtidos: altura (H), diâmetro de coleto (DC), massa de matéria seca da parte aérea (MSPA), da raiz (MSR), e total (MST), e calculada a relação entre a massa de matéria seca da parte aérea e raiz (MSPA/MSR) e o índice de qualidade de Dickson (IQD). A fertilização nitrogenada resultou em ganhos no crescimento e qualidade das mudas de ambas as espécies estudadas. As fontes e a interação fontes × doses não foram significativas para todas as variáveis estudadas. Para as condições estudadas, recomenda-se a dose de 185 mg dm-³ de N para a produção de mudas de Peltophorum dubium. Para a produção de mudas de Cassia grandi...

Limestone and topdress nitrogen application improves the quality of <i>Peltophorum dubium</i> (Sprengel) Taubert (Fabaceae – Caesalpinioideae) seedlings

“…In general, our results showed that limestone and N fertilizer application have a positive effect on most of the growth and quality traits of Peltophorum dubium seedlings, and when Peltophorum dubium seedlings are produced in a substrate consisting of a Cerrado sandy soil, the limestone application and use of 200 mg N dm -3 in topdressing should be recommended to obtain high-quality seedlings. These results confirmed those reported by Soares et al (2017), who applied rates ranging from 0 to 200 mg N dm -3 from different sources of N fertilizer, and showed that the optimum N fertilizer rate for the production of Peltophorum dubium seedlings grown in clay soil was 185 mg N dm -3 .…”

“…The increase in seedling growth with the application of N fertilizer was expected, since this nutrient plays a fundamental role in physiologic metabolism, being part of several plant molecules and structures (Taiz et al, 2017). Positive responses of N fertilization on the production of Peltophorum dubium seedlings were reported by Cruz et al (2012), Souza et al (2013), andSoares et al (2017). Therefore, it is evident that the N fertilizer application provides higher quality Peltophorum dubium seedlings, being necessary N fertilizations when the demand of the plant is greater than the supply by the substrate.…”

Crescimento e qualidade de mudas de Citharexylum myrianthum em resposta à fertilização nitrogenada

“…Diversos trabalhos com espécies arbóreas corroboram com o resultado obtido nesse estudo, em que a fertilização nitrogenada influenciou de forma positiva o crescimento inicial e a qualidade das mudas de espécies florestais nativas (Cruz et al 2006, Gonçalves et al 2008, Marques et al 2009, Tucci et al 2009, Gonçalves et al 2010, Feitosa et al 2011, Cruz et al 2011, Caione et al 2012, Ciriello et al 2014, Mews et al 2015, Goulart et al 2016, Carvalho et al 2016, Soares et al 2017. O nitrogênio faz parte de vários compostos nas plantas, como aminoácidos, ácidos nucléicos e clorofila (Cantarella 2007), o que justifica sua absorção em maiores concentrações pelas plantas.…”

Influence of nitrogen fertilization in mother plants on the growth and quality of clonal seedlings of Coffea canephora ‘Robusta’ plants

“…An increase in N resulted in a a reduction in the dry mass of the cuttings. This occurred because increasing N promotes vegetative growth and stem elongation (CIRIELLO, GUERRINI & BACKES, 2014;SOARES et al, 2017), i.e., the greater availability of N may have resulted in thinner or less dense stems that were therefore lighter due to the competition for resources, such as solar radiation, caused by the higher number of secondary stems and cuttings and greater fresh mass of the stems (data not shown).…”