Early selection of sugarcane using path analysis.

The aim of this study was to analyze sugarcane (Saccharum officinarum) biometric and technological data, obtained at different timepoints, using path analysis. The experiment was conducted in União, PI, Brazil, and evaluated 12 sugarcane genotypes (RB036066, RB9438, RB935744, RB021764, RB021754, RB021534, RB966229, RB977540, RB863129, and RB987935, and the varieties RB92579 and RB867515 as controls) in a randomized block design with four replications. Data were collected at six timepoints that were spaced 30 days apart (90, 120, 150, 180, 210, and 240 days). Direct and indirect effects of the following production components were compared: stalk length, stalk diameter, internode length, number of tillers, number of green leaves, and stalk dry matter. The technological variables evaluated were total recoverable sugar, degrees Brix, tons of polarization (pol, apparent sucrose content) per hectare, juice purity, fiber, juice pol, and tons of sugarcane per hectare. The coefficients of determination were high in all path analyses, suggesting that the components evaluated explained a large part of the variation in stalk production and in the technological variables. Stalk diameter was the trait that best correlated with stalk dry matter yield at all timepoints, with positive values that were higher than the residual effect. This demonstrates the possibility of obtaining significant gains via indirect selection for stalk dry matter yield via stalk diameter or via stalk diameter and number of tillers. The technological variables degrees brix and juice pol were the traits that best correlated with total recoverable sugar production, indicating that they could be used to indirectly select for total recoverable sugar.

Stability of annual biomass energy production of elephant grass (Pennisetum purpureum Schum.) genotypes in the Northern region of the Rio de Janeiro State, Brazil.

The objectives of this study were to estimate the stability of dry biomass production of elephant grass genotypes under an annual harvest regime, in soil-climatic conditions of the Northern region of the Rio de Janeiro State, Brazil, and to compare methodologies for stability analyses of Yates and Cochran (YC), Plaisted and Peterson (PP), Annicchiarico (ANN), Lin and Binns (LB), Huenh (HU), and Kang and Phan (KP). A randomized block design with 83 treatments and two replicates was adopted. Four annual harvests were performed (2012-2015) and dry matter yield (DMY, t.ha-1.year-1) was evaluated. Individual and combined analyses of variance for DMY revealed significant effects for genotypes, harvests, and for the genotype x harvest interaction at the probability levels of 1 and 5%. Genotypes indicated by the YC and PP methods are associated with higher stability and lower DMY. The weighting of KP with YC and PP was highly effective in associating stability with DMY. The LB and ANN methods showed strong agreement with each other and produced similar classifications as to phenotypic stability, and so we recommend using one or the other. Genotypes Elefante Cachoeiro do Itapemirim, Cuba-116, Taiwan A-46, P241 Piracicaba, Taiwan A-144, Cameroon - Piracicaba, 10 AD IRI, Guaçu/I,Z,2, Mineirão IPEACO, Taiwan A-121, IJ7125 cv EMPASC308, 903-77, Mole de Volta Grande, and Porto Rico 534-B showed high stability and DMY, standing out as promising genotypes for the soil-climatic conditions of the Northern region of the Rio de Janeiro State. The methodologies based on ANOVA and non-parametric analyses were complementary and increased reliability in the recommendation of genotypes.

Biometric analysis of arabica coffee grown in low potassium nutrient solution under greenhouse conditions.

Genetic parameters and associations between morpho-agronomic traits and nutritional efficiencies of arabica coffee cultivars were estimated to identify promising traits to assist in the selection of coffee genotypes efficient in potassium use, under limiting conditions of this nutrient. The experiment was conducted in a greenhouse with 20 arabica coffee cultivars grown in nutrient solution with a low potassium level (1.5 mM), using a randomized block design with three replicates. The traits evaluated were plant height, number of leaves, number of nodes, internode length, stem diameter, leaf area, rooting efficiency, potassium absorption efficiency, potassium translocation efficiency, biomass production efficiency, and potassium use efficiency. Genetic variability among coffee cultivars for all the evaluated traits was found. The phenotypic variance for all traits showed a higher contribution of genetic variance compared to environmental variance. Plant height, internode length, stem diameter, leaf area, biomass production efficiency, and potassium use efficiency had a genotypic determination coefficient (H2) above 80% and variation index greater than one. Leaf area and stem diameter had significant and positive genetic correlations with rooting, biomass production, and potassium use efficiencies. Stem diameter has great potential for use in breeding programs with a goal of indirect selection of cultivars that have greater potassium use efficiency in environments with restrictions of this nutrient.

Use of elephant grass for energy production in Campos dos Goytacazes-RJ, Brazil.

Elephant grass is a tropical forage plant widely distributed throughout Brazil. It was first exclusively used in the livestock sector as cattle feed. The grass is characterized by its high productivity and photosynthetic capacity and is considered as an alternative source of renewable energy. Here, we estimated the general combining ability of the parents and specific combining ability of the hybrids based on morpho-agronomic biomass-quality traits. The experiment was conducted in a randomized block design with 3 replicates. The diallel was composed of 16 hybrids and 2 groups of genitors. In the diallel analysis of variance, we observed a significant difference among treatments. A significant difference was observed among genitors for dry matter production (DMP). For the general combining ability of group 1, the traits leaf blade width, DMP, height, percentage of neutral detergent fiber, percentage of hemicellulose, percentage of lignin, percentage of acid detergent fiber, and percentage of cellulose were significant. For the estimates of general combining ability of DMP, parents Porto Rico 534-B, Vruckwona, Taiwan A-146, and Mercker S. E. A. were 0.4748, 3.2819, 1.1659, and 0.4317. The parents of Mercker S. E. A. and Porto Rico 534-B produced the highest percentage of detergent fiber and percentage of lignin with values of 0.1482 and 0.0856. Thus, parents Vruckwona, Porto Rico 534-B, and Taiwan A-146 are promising for integration into breeding programs. The best hybrid combinations for DMP were 1 x 5, 1 x 8, 2 x 6, 3 x 7, and 4 x 5.

Snap bean recommendation based on different methods of phenotypic stability.

In order to recommend the best strains of snap beans from the Universidade Estadual do Norte Fluminense (UENF) breeding program, different methods of analysis of phenotypic stability were adopted to evaluate the performance of 14 lines (F(9) and F(10)) of indeterminate growth habit, which were compared with 3 controls, namely, 2 commercial varieties (Feltrin and Top Seed Blue Line) and 1 parent (UENF-1445). The experiments were conducted in Bom Jesus do Itabapoana in 2010 and 2011, and in Cambuci in 2011. The experiment was arranged in a randomized block design with 4 replications. To complement the information obtained by different methods, the UENF 7-5-1 strain was indicated for favorable environments (Bom Jesus do Itabapoana; 2010 and 2011), UENF 7-10-1, UENF 7-14-1, and UENF 7-20-1 strains were indicated for an unfavorable environment (Cambuci), and UENF 7-12-1 was indicated for both.

Controle de plantas invasoras em cultivo orgânico e convencional de capim-limão (Cymbopogon citratus (DC) Stapf. ) / Weed control in organic and conventional crops of lemongrass

O cultivo orgânico é preconizado para o capim-limão (Cymbopogon citratus (DC) Stapf.) como planta medicinal promissora ao desenvolvimento de fármacos no Brasil. Objetivou-se avaliar técnicas de controle de plantas invasoras sobre componentes de produção de capim limão em cultivos orgânico e convencional. Dois experimentos foram instalados sob delineamento inteiramente casualizado, com quatro repetições, em esquema fatorial 2x2x3, considerando-se duas áreas (orgânico e convencional) e os tratamentos combinando cobertura morta (presente e ausente) e técnicas de controle de plantas invasoras (capina manual, roçada e nenhuma). Altura, perfilhamento, teor e rendimento total de óleo essencial de capim-limão no cultivo orgânico foram superiores ao convencional, mas a produtividade de biomassa aérea seca não diferiu entre ambos. A capina, com ou sem cobertura morta, favoreceu o rendimento de óleo no cultivo orgânico.

Organic farming is recommended for lemongrass as a promising medicinal plant for drug development in Brazil. The purpose of this paper was to evaluate the effect of the techniques to control weed on the plant height, tillering, biomass productivity, content and yield of the essential oil of lemon grass in organic and conventional crops. Two experiments were set in a completely randomized design with four replications, at a 2x2x3 factorial scheme, considering two areas (organic and conventional) and treatments combining mulching (present and absent) and weed control techniques (hoeing, skimming and none). Plant height, tillering, content and yield of the essential oil of lemongrass were better in the organic crop, but the biomass productivity did not differ between both areas. The biomass production was better in the conventional crop as to weed control, with or without mulching, and for organic crop under hoeing or skimming with mulching. Hoeing or skimming with no mulching improved the oil content in organic crops. Hoeing or skimming with mulching was better than any other weed control technique with no mulching, and hoeing was better than skimming, justifying its recommendation as a technique for this crop system.