ResumoA adubação assume papel fundamental na fase de produção de mudas de frutíferas, a fim de garantir bom desenvolvimento e precocidade de produção. Objetivou-se avaliar os efeitos de doses de nitrogênio e potássio no crescimento de mudas de goiabeira. Estacas herbáceas de goiabeiras, cultivar "Paluma", foram enraizadas em câmara de nebulização, em sacos de polietileno contendo substrato. O experimento foi conduzido em viveiro comercial, em blocos casualizados, em esquema fatorial 4 x 4, sendo quatro doses de nitrogênio (0, 552, 828 e 1.104 mg dm -3 ) e quatro doses de potássio (0, 726, 1.089 e 1.452 mg dm -3 ), com três repetições e três plantas por parcela. No enchimento dos sacos (1,5 dm -3 ), foram adicionados 100 mg dm -3 de P, enquanto os adubos contendo nitrogênio e potássio foram parcelados em três vezes. As mudas foram avaliadas aos 120 dias. Observou-se efeito significativo do nitrogênio nas variáveis altura, diâmetro do caule, número de folhas, índice SPAD, massa seca de folhas, caule, total, índice de qualidade de Dickson e acúmulo de N. A adubação com potássio não promoveu diferenças significativas nos parâmetros biométricos, índice SPAD e IQD. Palavras-chave: Psidium guajava, fertilização nitrogenada, fertilização potássica, substrato AbstractThe fertilization takes key role at the production of fruit seedlings in order to ensure a good development and early production. The aim of this study was to evaluate the effects of nitrogen and potassium on the growth of guava seedlings. Herbaceous stakes of guava, "Paluma" cultivar, were rooted in a mist room, in polyethylene bags containing substrate. The experiment was conducted in a commercial nursery, in randomized blocks and a factorial scheme 4x4, with four doses of nitrogen (0, 552, 828 and 1104 mg dm -3 ) and four doses of potassium (0, 726, 1,089 and 1,452 mg dm -3 ) in three replications and three plants for parcel. During the filling of the bags (1,5 dm -3 ), were added 100 mg dm -3 of superphosphate, while fertilizers containing nitrogen and potassium were split into three times. After 120 days, the seedlings were evaluated. There was a significant effect of nitrogen in the variables height, stem diameter, number of leaves, SPAD index, dry weight of leaves, stems, total, Dickson quality index, and nitrogen accumulation. The fertilization with potassium did not influence the biometric parameters, SPAD index and Dickson quality index.

Guava response to fertilization can be monitored through plant tissue analysis. Correct interpretation of these results, based on standard levels, is of great importance for correct nutrient management of the crop. However, standard levels are constantly criticized for not considering interactions among elements. To improve the nutritional diagnosis of 'Paluma' guava (Psidium guajava L., Myrtaceae), an experiment was conducted using nitrogen fertilization (0, 0.5, 1.0, and 2.0 kg per plant per cycle of N, with urea as a source with 45 % N), and potassium fertilization (0, 0.55, 1.1, and 2.2 kg per plant per cycle of K 2 O, with potassium chloride as a source with 60 % K 2 O) in an irrigated commercial area for five consecutive cycles, 2009 through 2012, observing the influence of fertilizers and climate and assessing yield and leaf element content, using the concept of isometric log ratios (ilr) to interpret leaf analysis results (N, P, Ca, Mg, K, and S). This paper showed that nutrient balances and nutrient concentration values can be interpreted coherently using compositional data analysis. Ranges of nutrient balances also were established for "Paluma" guava and validated through ranges grounded in nutrient contents currently used in Brazil. Nitrogen fertilization increased "Paluma" guava yield. The 0.5 kg N application rate per plant and the other studied treatments practically showed the same results, and their values were affected by pruning time as well as the nutrient balances.

Maize is one of the most nutrient demanding staple crops. Tissue nutrient diagnosis of maize is currently conducted using critical nutrient concentration or dual ratio ranges, but such diagnoses are pathological as biased by data redundancy, sub-compositional incoherence and non-normal distribution. The use of orthogonal balances, a compositional data analysis technique, avoids such biases. Our objective was to develop foliar nutrient balance standards for maize. We collected 758 grain yields (15.5% moisture content) and foliar samples at silk stage in maize fields of southern Quebec, Canada, and analyzed ten nutrients in tissues (N, P, K, Ca, Mg, B, Cu, Zn, Mn, Fe). Nutrients were arranged into ad hoc balances and computed as isometric log ratios (ilr). An optimized binary classification performed by a customized receiver operating characteristic procedure showed that a critical Mahalanobis distance of 4.21 separated balanced from imbalanced specimens about yield cut-off of 11.83 Mg grain·ha −1 with test performance of 86%. Quebec maize balance standards differed from published standards computed from DRIS norms collected in other agroecosystems. The Redfield N/P ratio in maize leaves was found to be the least variable balance across regions of the world. The DRIS dual ratios and raw concentration values were found to be geometrically inadequate for conducting diagnosis. The unbiased nutrient balance diagnosis combined the critical Mahalanobis distance and a mobile representation of nutrient balances with ilr means of true negative (TN) specimens centered at fulcrums and back-transformed ilr values of TN specimens into raw concentrations loading the buckets below. Nutrients can be appreciated as relative shortage, adequacy or excess in the concentration domain following statistical analysis and diagnosis in the unbiased balance domain.

RESUmo -a nutrição dos pomares é fator preponderante à produtividade, sendo necessário conhecer as doses adequadas de fertilizantes e sua influência nos atributos qualitativos dos frutos para industrialização. O trabalho objetivou avaliar os efeitos de diferentes doses de nitrogênio e potássio sobre a produtividade de goiabeiras e sobre os valores de pH, conteúdo de sólidos solúveis (SS) e de acidez titulável (at), além da relação polpa/miolo das goiabas. o experimento foi conduzido em Vista alegre do alto-SP, em pomar de goiabeiras 'Paluma', com sete anos de idade, irrigado, manejado com podas, durante três ciclos consecutivos de produção. O solo do pomar é o Argissolo Vermelho-Amarelo distrófico. o delineamento experimental foi em blocos ao acaso, em esquema fatorial, com quatro doses de nitrogênio (0; 0,5; 1 e 2 kg planta -1 de N) e quatro de potássio (0; 0,55; 1,1 e 2,2 kg planta -1 de K 2 O), com três repetições. A adubação nitrogenada aumentou a produtividade e o pH dos frutos, sendo explicados por modelos quadráticos de regressão polinomial; diminuiu linearmente a relação polpa/miolo e não influenciou os teores de SS e de AT. Por outro lado, a adubação potássica e a interação N x K não apresentaram efeitos significativos sobre a produtividade, bem como sobre as demais características avaliadas. Termos para indexação: Psidium guajava, goiaba, nitrogênio, potássio. NITRoGEN AND PoTASSIUm FERTILIZATIoN IN 'PALUmA' GUAVA TREES: I. EFFECT oN PRoDUCTIVITY AND FRUIT QUALITY FoR INDUSTRIALIZATIoNABSTRACT -The nutrition of the orchards is the major factor of productivity, being necessary to know the proper doses of fertilizers and their influence on fruit quality attributes for industrialization. This study evaluated the effects of different doses of nitrogen and potassium on the productivity of guava trees and also on the values of pH, soluble solids (SS), titratable acidity (TA) and pulp/kernel ratio of guavas. The experiment was conducted at Vista Alegre do Alto, SP in an irrigated 'Paluma' guava orchard, 7 years old, managed with pruning during three consecutive cycles of production. The soil of the area was dystrophic Ultisol. The experimental design was the randomized blocks, in factorial, with four nitrogen doses (0, 0.5, 1 and 2 kg of n plant -1 ) and four of potassium (0, 0.55, 1.1 and 2.2 kg of K 2 o plant -1 ), with three replications. Nitrogen fertilization increased productivity and the pH of the fruit, being explained by the quadratic polynomial regression models; reduced linearly the pulp/kernel ratio and do not influenced the SS and TA values. On the other hand, potassium fertilization and N x K interaction had no significant effects on productivity and the other characteristics evaluated.

A utilização de fontes alternativas de nutrientes, provenientes especialmente de resíduos e subprodutos da agroindústria, pode ser estratégia importante na ciclagem de elementos essenciais, garantindo destino adequado de materiais que seriam descartados. Assim, objetivou-se avaliar a aplicação de doses do subproduto da indústria processadora de goiabas sobre a fertilidade de um Argissolo, sob pomar de goiabeiras. As doses de resíduo foram estabelecidas em função dos teores de N no material. O delineamento empregado foi o de blocos casualizados, com cinco tratamentos e quatro repetições, sendo as doses do resíduo (moído) iguais a: zero; 9; 18; 27 e 36 t ha-1 (peso do material seco). Foram feitas cinco aplicações do subproduto em: 2006, 2007, 2008, 2009 e 2010. O subproduto da indústria processadora de goiabas promoveu alterações na fertilidade do solo do pomar. Com o aumento das doses, houve incremento das concentrações de fósforo no solo em todas as análises realizadas. As concentrações de manganês aumentaram, e houve redução do valor pH do solo nos últimos anos de condução do experimento. Observou-se, na camada subsuperfical (0,20-0,40 m), após a aplicação contínua do subproduto, aumento na concentração de fósforo em função das doses do subproduto.

The objective of this work was to propose preliminary Diagnosis and Recommendation Integrated System (DRIS) norms and derive critical levels and nutrient sufficiency ranges in the leaves of guava plants in commercial nursery conditions. Sixty-eight leaf samples were evaluated from fertilization trials with seedlings. In the low-yield subpopulation (84% of the population), the limiting nutrients by deficiency in descending order were nitrogen (N)> copper (Cu)>phosphorus (P)= potassium (K)> manganese (Mn)> iron (Fe)= zinc (Zn)> sulfur (S)> boron (B) = magnesium (Mg)> calcium (Ca) , and the limiting ones by excess in descending Downloaded by [McMaster University] at 11:36 24 March 2015 ACCEPTED MANUSCRIPT ACCEPTED MANUSCRIPT 2 order were B>Ca>Fe>Mn>S>Mg>Cu>P>Zn>N=K. The ranges of the appropriate DRIS indiceswere 24 to 28, 2.4 to 3.1, 21 to 29, 6 to 8, 1.9 to 2.9 and 1.9 to 2.3 (g kg -1 ) for the macronutrients N, P, K, Ca, Mg and S, respectively, and 35 to 48, 4 to 15, 68 to 93, 31 to 60 and 180 to 245 (mg kg -1 ) for the micronutrients B, Cu, Fe, Mn and Zn, respectively. The dry matter production of guava seedlings was associated with the nutritional status.

The Brazilian guava processing industry generates 5.5 M Mg guava waste year−1 that could be recycled sustainably in guava agro-ecosystems as slow-release fertilizer. Our objectives were to elaborate nutrient budgets and to diagnose soil, foliar, and fruit nutrient balances in guava orchards fertilized with guava waste. We hypothesized that (1) guava waste are balanced fertilizer sources that can sustain crop yield and soil nutrient stocks, and (2) guava agroecosystems remain productive within narrow ranges of nutrient balances. A 6-year experiment was conducted in 8-year old guava orchard applying 0–9–18–27–36 Mg ha−1 guava waste (dry mass basis) and the locally recommended mineral fertilization. Nutrient budgets were compiled as balance sheets. Foliar and fruit nutrient balances were computed as isometric log ratios to avoid data redundancy or resonance due to nutrient interactions and the closure to measurement unit. The N, P, and several other nutrients were applied in excess of crop removal while K was in deficit whatever the guava waste treatment. The foliar diagnostic accuracy reached 93% using isometric log ratios and knn classification, generating reliable foliar nutrient and concentration ranges at high yield level. The plant mined the soil K reserves without any significant effect on fruit yield and foliar nutrient balances involving K. High guava productivity can be reached at lower soil test K and P values than thought before. Parsimonious dosage of fresh guava waste should be supplemented with mineral K fertilizers to recycle guava waste sustainably in guava agroecosystems. Brazilian growers can benefit from this research by lowering soil test P and K threshold values to avoid over-fertilization and using fresh guava waste supplemented with mineral fertilizers, especially K. Because yield was negatively correlated with fruit acidity and Brix index, balanced plant nutrition and fertilization diagnosis will have to consider not only fruit yield targets but also fruit quality to meet requirements for guava processing.

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