Eliana Aparecida Schammass

Avaliação de características de valor nutritivo das gramíneas forrageiras Marandu, Setária e Tanzânia nas estações do ano

Foi realizado um experimento de campo, em blocos completos ao acaso, em esquema de parcelas subdivididas, com 12 repeticoes, com o objetivo de comparar os teores de proteina bruta (PB), fibra em detergente neutro (FDN) e digestibilidade in vitro da materia seca (DIVMS), da planta inteira e suas fracoes lâmina e haste do Marandu (Brachiaria brizantha Stapf. cv. Marandu), da setaria (Setaria sphacelata [Schum.] Moss var. sericea [Stapf.] cv. Kazungula) e do Tanzânia (Panicum maximum Jacq. cv. Tanzânia-1), em cortes aos 35 dias de crescimento, nas estacoes de primavera (21/11 a 25/12/97), verao (29/12/97 a 02/02/98), outono (13/04 a 18/05/98) e inverno (28/05/98 a 01/07/98). As parcelas foram representadas pelas gramineas forrageiras e as subparcelas, pelas estacoes do ano. Marandu e Tanzânia nao diferiram quanto aos teores de PB e DIVMS. A Setaria apresentou teores de PB mais elevados que o Marandu, no outono e no inverno, porem menor DIVMS que este, nas quatro estacoes. Tanzânia e Setaria nao diferiram quanto aos seus teores de PB e DIVMS, nas quatro estacoes. Os teores de FDN foram maiores no Tanzânia, mas nao diferiram entre Marandu e Setaria. O mais alto valor nutritivo, considerando-se maiores teores de proteina e DIVMS e menores teores de FDN, foram observados no outono, independentemente da especie forrageira.

Utilization of nitrogen from green manure and mineral fertilizer by sugarcane

Given their potential for biological nitrogen fixation, legumes used as green manure are an alternative source of nitrogen to crops, and can supplement or even replace mineral nitrogen fertilization. The utilization of nitrogen by sugarcane (Saccharum spp.) fertilized with sunn hemp (Crotalaria juncea L.) and ammonium sulphate (AS) was evaluated using the 15N tracer technique. Amounts of 195.8 kg and 70 kg N per hectare, respectively, of sunn hemp and AS were added in the following treatments: without green manure and without AS; without green manure, with AS -15N; with green manure-15N and with AS; with green manure-15N, without AS; with green manure and with AS-15N. Four samples from the leaves +3 were collected and 2 m of the sugar cane row were harvested to estimate crop yield. The results for N contents (g kg-1), isotopic abundance of N (atoms % 15N) in leaf +3 samples, and sugarcane productivity were used to calculate cumulative N, nitrogen in the plant derived from the fertilizer-Ndff (% and kg ha-1), as well as percent recovery of fertilizer N (R%). Sugarcane was analysed and pol and total recovered sugar calculated. The highest Ndff percentages were observed eight months after sugarcane planting for treatments containing green manure without mineral N, and green manure with mineral N, at 15.3 and 18.4%, respectively. The best nitrogen recovery was observed during harvest, 18 months after planting; the treatment containing mineral fertilizer showed 34.4% recovery, while the sum between mineral N plus green manure N showed 40.0%. Treatments containing green manure plus mineral N changed soil attributes, by increasing Ca and Mg contents, sum of bases, pH, and base saturation, and decreasing potential acidity. In the plant, those treatments increased Ca and K contents.

Crop rotation biomass and arbuscular mycorrhizal fungi effects on sugarcane yield

A cana-de-acucar (Saccharum spp.) vem sendo cultivada no Brasil para producao de acucar e agroenergia. Em seu sistema de producao, apos um ciclo de 4 a 8 anos, e possivel a rotacao com plantas de cobertura, antes do seu replantio, para melhoria do solo e geracao de renda. Estudou-se a caracterizacao e produtividade de biomassa de leguminosas (como adubos-verdes) e girassol (Helianthus annuus L.), a ocorrencia natural de micorrizas, o teor de acucar e a produtividade em colmos da cana-de-acucar IAC 87-3396 e a viabilidade economica desse sistema com cultivo apos as opcoes de rotacao, com quantificacao da produtividade durante tres cortes consecutivos. O amendoim (Arachis hypogaea L.) cv. IAC-Caiapo, girassol cv. IAC-Uruguai e mucuna-preta (Mucuna aterrimum Piper and Tracy) foram as culturas que apresentaram maior percentagem de colonizacao por fungos micorrizicos. O girassol foi a planta de cobertura que mais extraiu nutrientes do solo, seguido por amendoim (Arachis hipogaea L.) cv. IAC-Tatu e feijao-mungo (Vigna radiata L. Wilczek). A colonizacao por fungos micorrizicos mostrou correlacao positiva com a altura de plantas de cana no primeiro corte (p = 0,01 e R = 0,52), mas nao se correlacionou com a produtividade de colmos ou acucar. No primeiro corte, o girassol foi a cultura de rotacao que ocasionou o maior aumento de produtividade, da ordem de 46% em colmos e de 50% na quantidade de acucar, em comparacao com a testemunha. Com excecao dos amendoins, todas as culturas em rotacao aumentaram a renda liquida do sistema na media de tres cortes de cana-de-acucar.

15N-labeled nitrogen from green manure and ammonium sulfate utilization by the sugarcane ratoon

Leguminosas, como adubo verde, sao fontes alternativas de nitrogenio para as culturas e podem complementar ou mesmo substituir a adubacao mineral nitrogenada, devido ao seu potencial de fixacao biologica de nitrogenio (FBN). A utilizacao do nitrogenio pela cana-de-acucar (Saccharum spp.) fertilizada com crotalaria (Crotalaria juncea L.) e sulfato de amonio (SA) foi avaliada utilizando a tecnica de tracador 15N. As quantidades equivalentes a 196 e 70 kg de N por hectare foram adicionados como adubo verde crotalaria juncea (CJ) e como o sulfato de amonio (SA), respectivamente, nos seguintes tratamentos: (i) controle; (ii) SA15N; (iii) CJ15N + SA; (iv) CJ15N; e (v) SA15N + CJ. A cana-de-acucar foi cultivada por cinco anos e colhida tres vezes. A recuperacao do 15N foi avaliada nas duas primeiras colheitas. Na soma das tres safras, os maiores rendimentos de colmos foram obtidos com uma combinacao de adubos verdes e fertilizantes N inorgânicos, mas, no segundo corte rendimentos superiores foram observados nos tratamentos com CJ em comparacao com os observados com SA. A recuperacao de N nas primeiras duas safras consecutivas representou 19 a 21% do N aplicado como adubo verde e 46 a 49% do N aplicado como SA. As quantidades de N inorgânico derivado das fontes marcadas, presentes na camada 0-0,4 m do solo na primeira safra apos a aplicacao do N foram inferiores a 1 kg ha-1.

Variabilidade da dormência de sementes entre e dentro de espécies de Sesbania

Seed dormancy variability was analised among species and families of Sesbania SCOP. Thirteen families of the following five Sesbania species were evaluated: S. rostrata, S. exasperata, S. tetraptera, S. sesban and S. virgata. The trial was conducted at 20-30°C, for 15 days, in a completely randomized design with three replications of 50 seeds each. An analysis of variance was conducted unfolding the degrees of freedom of families within species. The coefficients of intraspecific genetic variation (CVgi) and genotypic determination (b) were estimated. Germination rates, measured indirectly by the average germination time, were also evaluated. High variability for seed dormancy was observed among species (P<0.01) and among families (P<0.01). S. virgata and S. tetraptera presented the highest dormancy, with average germination of 13.5 and 13.9%, respectively, while S. rostrata and S. sesban showed the lowest dormancy, with average germination of 68.3 and 60.5%. The estimated values of CVgi were low for all species, varying from 9.9 to 14.9%, indicating that most of the variability found in relation to dormancy in these populations is due to non-genetic factors. The estimated values of b were higher for S. tetraptera (b = 0.6769), S. sesban (b = 0.6332) and S. exasperata (b = 0.6306), indicating a possibility of selection for higher or lower dormancy levels. As for the germination rates, S. virgata was the slowest, in contrast with S. tetraptera and S. sesban, which presented the fastest germination rates. No significant differences for germination rates were observed among families.

Nitrogen supply to corn from sunn hemp and velvet bean green manures

Due to their nitrogen fixation potential, legumes represent an alternative for supplying nutrients, substituting or complementing mineral fertilization in cropping systems involving green manuring. The objective of this study was to evaluate the N balance in a soil-plant system involving green manures [sunn hemp (Crotalaria juncea L.) and velvet bean (Mucuna aterrima Piper & Tracy)], both labeled with 15N. They were incorporated into two soils of contrasting textural classes: a clayey Eutrudox and a sandy-clayey Paleudalf, both cultivated with corn. The research was carried out in a greenhouse, using pots containing 6 kg of air dried soil, to which the equivalent to 13 Mg ha-1 dry matter of above-ground mass plus 2.7 or 2.2 Mg ha-1 of velvet bean and sunn hemp roots were incorporated, respectively, with 15N labeling of either shoots or roots. One hundred days after emergence of the corn, the velvet bean residues provided higher accumulation of N in the soil, higher absorption by corn plants and accumulation in the shoot. The green manure decomposition was more intense in the medium-textured Paleudalf. The highest nitrogen losses were also observed in this soil.

Morphoagronomic genetic diversity in american wild rice species

To characterize the genetic variability among species and populations of South American wild rice, eleven populations of Oryza glumaepatula, seven of O. grandiglumis, four of O. latifolia and one of O. alta, from Brazil and Argentina, were evaluated. A greenhouse experiment was conducted in completely randomized blocks with 23 treatments. Twenty morphoagronomic traits were assessed. Univariate analyses were performed with 16 quantitative traits with the partitioning of populations within species. Significant differences (p<0.001) between species were observed for all the traits as well as among populations within the species. The most variable was O. glumaepatula followed by O. latifolia. Multivariate discriminant canonical and cluster analyses confirmed the separation of the highly diverse O. glumaepatula populations from the tetraploid species, and the high genetic variation among O. latifolia populations. Morphological differences among the three tetraploid species seemed to be enough to ascribe them at least the condition of species in statu nascendi.

Avaliação de características agronômicas e morfológicas das gramíneas forrageiras Marandu, Setária e Tanzânia aos 35 dias de crescimento nas estações do ano

A field plot experiment was conducted in the Instituto de Zootecnia, Nova Odessa-SP, in a split plot design with 12 replicates, to compare, in the grasses marandu (Brachiaria brizantha Stapf. cv. Marandu), setaria (Setaria sphacelata cv. Kazungula) and tanzania (Panicum maximum cv. Tanzania-1): dry matter yield, dry matter percentage, sward height, leaf blade percentage, apical meristem height, in cuts at 35 days of growth, in the spring (21/11 to 25/12/97), summer (29/12/97 to 02/02/98), fall (13/04 to 18/05/98) and winter (28/05 to 01/07/98) seasons. The plots were the grasses and the split-plots the year seasons. Tanzania always showed high leaf blade percentage and low apical meristem height and presented the highest dry matter yield during fall season, and in the spring and winter, its dry matter yield did not differ from the other grasses, that were alike in the four seasons. The Setaria grass showed the smallest dry matter percentage in the four seasons, and the smallest leaf blade percentage, during spring and summer, which can limit its intake by the animals.

Dietary effects of chelated zinc supplementation and lysine levels in ISA Brown laying hens on early and late performance, and egg quality

It has been hypothesized that zinc (Zn) levels beyond those that are nutritionally required may favor the utilization of dietary lysine, and consequently reduce the level of its inclusion into the diet. Therefore, the possible effects of interaction between chelated Zn and the level of lysine (Lys) on egg production and egg quality of laying hens were evaluated. In total, 720 ISA Brown layer hens aged 24 to 36 wk (early phase) and 48 to 60 wk (late phase) were allotted in a completely randomized factorial design that used 3 Zn and 5 Lys levels (6 replications, 8 birds/replication). All birds aged 37 to 47 wk (between early and late phases) were fed a standard diet and maintained under the same experimental design. The Zn levels used were 137, 309, and 655 mg/kg; and the Lys levels were 0.560, 0.612, 0.677, 0.749, and 0.851%. The optimal levels of Lys digestibility were based on laboratory analyses with regard to the weighted average relationship between 83.5% digestibility and the total Lys from principal ingredients. There was no effect of interaction found between the dietary levels of Zn and Lys for most of the variables studied; however, each had an independent effect on the variables. An increase in Zn from 137 to 655 mg/kg had no significant effect (P > 0.05) on the performance of hens in both phases; however, it showed a significant effect on egg quality (P < 0.01), principally on mineral composition. Increased Zn resulted in decreased shell weight, percentage of ash, yolk ash deposition, and total ash deposition. On the other hand, an increase in Lys from 0.560 to 0.851% significantly affected (P < 0.002) several performance parameters and the chemical composition of the eggs, including feed intake, feed conversion efficiency, BW gain, egg weight, and production. In conclusion, there was no interaction found between Zn and Lys, but higher dietary levels of chelated Zn reduced bird performance and egg quality parameters, whereas higher Lys levels could be beneficial to bird performance and egg quality.

Desempenho de cultivares de tomateiro em sistema orgânico sob cultivo protegido

Organic agriculture in Brazil has been increasing about 30% per year over the last few years, since consumers are seeking for healthier foods, i.e. nutritious and free of pesticide residues. Among organically grown vegetable crops, tomato is an attractive economic opportunity for growers. However, the lack of information about management practices and adapted cultivars to organic production systems under protected cultivation are pointed out as important constraints that prevents this activity to expand. This work aimed at evaluating the performance of indeterminate tomato cultivars in organic management systems in unheated plastic greenhouse. In both experiments tomato plants were staked. Plant spacing was 1.5 m between rows and 0.35 m between plants. They were planted in double line and spaced 0.8 m between lines and 0.6 m between plants (about 20,000 plants ha-1). The experiment was set up in a randomized complete block design, with four replications and eight treatments (cultivars: Avalon, Colibri, HTX-5415, HTX-8027, Sahel, San Marzano, San Vito, and Jane). Sahel hybrid exhibited an outstanding performance for marketable yield under organic cultivation. Tomato pinworm (Tuta absoluta) was a serious limiting pest for organically grown tomatoes, responding for 17% of damage in the fruits harvested from the evaluated cultivars.