Vinícius Ide Franzini

Phosphorus utilization by corn as affected by green manure, nitrogen and phosphorus fertilizers

O objetivo deste trabalho foi avaliar a utilizacao, pela planta de milho, do P proveniente de superfosfato triplo marcado com 32 P ( 32 P‑SFT), e do P proveniente do solo influenciado por doses de N e pelos adubos verdes (AV) crotalaria ( Crotalaria juncea ) e milheto ( Pennisetum glaucum ). O experimento foi realizado em vasos com 5 kg de Latossolo Vermelho distroferrico. Utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial 4x4x2, com quatro repeticoes. Os tratamentos foram: quatro doses de P, na forma de SFT (0, 0,175, 0,350 e 0,700 g de P por vaso); quatro doses de N, na forma de ureia (0, 0,75, 1,50 e 2,25 g de N por vaso); e crotalaria ou milheto, como adubo verde. Foram levadas em consideracao as adicoes de P e N pelos AV. Apos a maturacao fisiologica dos graos, foram avaliados: a producao de materia seca de milho, o teor de P, o P acumulado e o aproveitamento de P nos diferentes tratamentos. O aproveitamento do 32 P‑SFT pelo milho aumentou com o incremento da dose de N e diminuiu com o aumento da dose de 32 P‑SFT. O fertilizante mineral fornece a maior parte do P acumulado nas plantas de milho. O aproveitamento do 32 P‑SFT pelo milho foi de 13,12%, em media. A especie de adubo verde influencia a assimilacao de 32 P‑SFT pelas plantas.

Dris calculation methods for evaluating the nutritional status of oil palm in the Eastern Amazon

ABSTRACT This study aimed to evaluate six Diagnosis and Recommendation Integrated System (DRIS) calculation methods, including two ways to choose the nutrient ratio [F (Letzsch) or R (Nick) values] combined with three functions (Beaufils, Jones, or Elwali and Gascho), and to generate nutritional diagnoses for oil palm. A total of 144 foliar samples in 33 plots in the Eastern Amazon, Brazil, were used. Except for potassium (K) in all calculation methods, the DRIS indices showed no correlation with soil nutrients. Regardless of the formula, the nutritional balance index correlated with the productivity (significant r values) and similar diagnostics were obtained. These diagnoses were reliable according to the chi-square test (χ2), and most observed frequencies presented χ2 calculated less than χ2 tabulated. The average frequencies of samples with nutrient deficiency were 51%, 42%, 37%, 35%, 32%, 30%, 30%, 25%, 20%, 12%, and 12% for samples with nitrogen (N), boron (B), manganese (Mn), sulfur (S), K, copper (Cu), iron (Fe), zinc (Zn), calcium (Ca), phosphorus (P), and magnesium (Mg), respectively. All tested DRIS methods may be used, and their diagnoses indicate the most common nutritional deficiencies in oil palm.

Utilization of nitrogen (15N) from urea and green manures by rice as affected by nitrogen fertilizer rate.

The use of green manures (GMs) in combination with nitrogen (N) fertilizer application is a promising practice to improve N fertilizer management in agricultural production systems. The main objective of this study was to evaluate the N use efficiency (NUE) of rice plant, derived from GMs including sunn hemp (Crotalaria juncea L.), millet (Pennisetum glaucum L.) and urea in the greenhouse. The experimental treatments included two GMs (sunn hemp-15N and millet-15N), absence of N organic source (without GM residues in soil) and four N rates, as urea-15N (0, 28.6, 57.2 and 85.8 mg N kg-1). The results showed that both rice grain and straw biomass yields under sunn hemp were greater than that of millet or without the application of GM. The NUE of rice under sunn hemp was greater than that under millet (18.9 and 7.8% under sunn hemp and millet, respectively). The urea N application rates did not affect the fertilizer NUE by rice (53.7%) with or without GMs. The NUE of GMs by rice plants ranged from 14.1% and 16.8% for root and shoot, respectively. The study showed that green manures can play an important role in enhancing soil fertility and N supply to subsequent crops.

SISTEMA DE PRODUÇÃO DE MUDAS EM HÍBRIDOS INTERESPECÍFICOS ENTRE CAIAUÉ E DENDÊ

The objective of this study was to evaluate three systems of seedling production of interspecific hybrids of American oil palm and African oil palm (HIE), difference between 12 sib progenies of BRS Manicore cultivar and the interaction between these two factors. The production systems were evaluated: (i) two-stage nursery with the initial shading (conventional system), (ii) two-stage nursery without shading and (iii) one-stage nursery without shading. The variables evaluated were plant height, number of leaves and stem diameter at 106, 191 and 393 days after sowing. In all variables and periods analyzed, the genotype and environmental factors were significant to F test, but the interaction genotype x environment was not significant. The best development of seedlings in the nursery production system occurred in one-step nursery without shading. The two stages nursery with shading in pre-nursery, which is currently the most widely adopted, resulted in lower seedling development.

Phosphorus uptake efficiency, root morphology and architecture in Brazilian wheat cultivars

Abstract The main aims of this study were to evaluate the P uptake of Brazilian wheat cultivars and to identify the root traits involved in P uptake capacity. Two greenhouse studies were carried out. An isotopic dilution technique with 32P as a tracer was used in the first experiment. The root morphology and architecture was evaluated in the second experiment. The results indicated differences in P uptake between the cultivars. The cultivars with higher values of P uptake exhibited total root shallow, which enhances root proliferation in P-rich surface soil. Twenty-one cultivars showed potentially greater phosphorus uptake efficiency, and we observed the importance of root traits for improving the P uptake ability.