EFEITOS DO MANEJO HÍDRICO E DA APLICAÇÃO DE POTÁSSIO NAS CARACTERÍSTICAS MORFOFISIOLÓGICAS DE MUDAS DE Eucalyptus Grandis W. (Hill ex. Maiden) Magali Ribeiro da Silva1; Antonio Evaldo Klar2; José Raimundo Passos31Departamento de Recursos Naturais, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu, magaliribeiro@fca.unesp.br2Departamento de Engenharia Rural, Faculdade de Ciências Agronômicas, Universidade Estadual Paulista, Botucatu3Departamento de Bioestatística, Instituto de Biociências, Universidade Estadual Paulista, Botucatu, SP 1 RESUMO O trabalho teve por objetivo avaliar os efeitos do manejo hídrico e da adubação potássica realizados durante a fase de rustificação, na qualidade de mudas de Eucalyptus grandis. O experimento foi conduzido na Faculdade de Ciências Agronômicas da UNESP – Botucatu, e constituiu-se de um fatorial 2X4, sendo dois manejos hídricos (mudas irrigadas ao atingir as tensões de retenção de água pelo substrato de 0,01 MPa ou 1,5 MPa) e quatro doses de K (0, 75, 150 e 300 mg L-1). Foram feitas avaliações de: altura da parte aérea, diâmetro de colo, matéria seca da parte aérea e da radicular, matéria seca total, área foliar, relação altura da parte aérea / diâmetro de colo das mudas, teor de clorofila e taxa de transpiração. Os resultados morfológicos indicaram que somente a matéria seca radicular (MSR) diferiu estatisticamente em função do K aplicado. O estresse hídrico não teve efeito nas características morfológicas. Com relação às características fisiológicas, observou-se que os maiores teores de clorofila foram encontrados nas mudas submetidas ao maior estresse hídrico e maiores doses de K. As maiores taxas de transpiração foram observadas nas mudas dos tratamentos submetidos ao estresse hídrico mínimo. Não houve variação significativa entre as doses de K sobre a transpiração. UNITERMOS: Eucalyptus, rustificação, qualidade de mudas, viveiro, fertilização. SILVA, M. R. da; KLAR, A. E.; PASSOS, J. R. EFFECTS OF WATER MANAGEMENT AND POTASSIUM APPLICATION ON THE MORPHOPHYSIOLOGICAL CHARACTERISTICS OF SEEDLINGS OF Eucalyptus grandis W. (Hill ex. Maiden) 2 ABSTRACTS The objective of this study was to evaluate the effect of water management and potassium fertilizing applied during the hardening phase on the quality of Eucalyptus grandis seedlings. The experiment was conducted at the School of Agronomical Sciences of UNESP, Botucatu, and consisted of a factorial design 2X4; two water managements (seedlings irrigated when reaching water retention tensions by the substrate) and four doses of K (0, 75, 150 and 300 mg L-1). The following evaluations were made: shoot height, stalk diameter, shoot and root dry weight, total dry weight, leaf area, relation between seedling lap shoot height and diameter, transpiration rate and chlorophyll content. Morphological results showed that only the dry root weight differed statistically due to the K applied. The water management had no effect on the morphological characteristics. As to the physiological characteristics it was observed that the highest the chlorophyll contents were found in seedlings that had undergone the greatest water stress and K doses. The highest transpiration rates were observed in the seedlings of the treatments undergoing minimum water stress. The K levels did not influence transpiration statistically. KEYWORDS: Eucalyptus, hardening, quality of seedlings, nursery, fertilization
The contribution of growth and turnover to the muscle delta(13)C change process was investigated using mathematical models which associate delta(13)C change to time of intake of a new diet or increase in body mass. Two groups of Nile tilapia (Oreochromis niloticus) were fed on diets based on C3 (delta(13)C=-25.64+/-0.06 per thousand) or C4 (delta(13)C=-16.01+/-0.06 per thousand) photosynthetic cycle plants to standardize the muscle delta(13)C. After establishing the carbon isotopic equilibrium, fish (mean mass 24.12+/-6.79 g) then received the other treatment diet until a new carbon isotopic equilibrium could be established, characterizing T1 (C3-C4) and T2 (C4-C3) treatments. No significant differences were observed in fish productive performance. Good fits were obtained for the models that associated the delta(13)C change to time, resulting in carbon half-life values of 23.33 days for T1 and 25.96 days for T2. Based on values found for the muscle delta(13)C change rate from growth (0.0263 day(-1) and 0.0254 day(-1)) and turnover (0.0034 day(-1) and 0.0013 day(-1)), our results indicate that most of the delta(13)C change could be attributed to growth. The application of model that associated the delta(13)C change to body mass increase seems to produce results with no apparent biological explanation. The delta(13)C change rate could directly reflect the daily ration and growth rate, and consequently the isotopic change rates of carbon and other tissue elements can be properly used to assess different factors that may interfere in nutrient utilization and growth.
The effects of grain-based diets from C3 or C4-cycle plants on muscle delta(13)C change process in Nile tilapia (Oreochromis niloticus) fingerlings were investigated. Two groups of sex reversal males Nile tilapia fingerlings were fed with isoproteic (32.0% DP) and isocaloric (3200 kcal DE/kg) diets, differing from each other by their delta(13)C. Muscle samples were collected and the carbon isotopic composition was measured. For C4 diet, the formula for the muscle delta(13)C change related to the intake time of a new diet was delta(13)C=-14.88-9.21e(-0.0209t) and the half-life (T) of the muscle carbon was 33.2 days. For C3 diet, the formula was delta(13)C=-25.43+8.59e(-0.0533t) with T=13 days. The C3 diet was considered more appropriate based on its palatability and consequent larger food intake than the C4 diet, resulting in an increased muscle delta(13)C change rate. However, for future studies, would be necessary to mix both the C3 and C4 feedstuffs to formulate diets nutritionally appropriated, with contrasting stable isotopes signatures. Tissue delta(13)C change rate is therefore indicated as a promising tool to better understand the biotic and abiotic factors that influence nutrients utilization from the diet and animal growth.
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