Lucas Nunes da Luz

Correlations and path analysis of peanut traits associated with the peg

By correlation and path-coefficient analysis, the most relevant traits for selection for peanut pod yield were identified among the following: total number of pegs (TNP), number of pegs in the lower third of the plant (NPLTh), number of mature pods (NMP), main stem height (MSH), and reproductive efficiency (EF1 and EF2). The trial consisted of 15 F2:3 progenies derived from a cross of variety BR 1 and the advanced line CNPA 280 AM, evaluated in a randomized block design with three replications. The lines with best reproductive efficiency were L.8 and L.11. Path analysis detected a strong direct effect of the number of pegs in the lower plant third on the number of mature pods. This finding justifies the use of the number of pegs in the lower plant third in selection of peanut populations for number of mature pods.

Combined selection and multivariate analysis in early generations of intraspecific progenies of peanuts

Selection indexes are useful tools for the simultaneous selection of several descriptors aiming to promote genetic gains and a reliable advancement of segregating populations. This study tested the use of selection index of distance from the genotype to the ideotype to assist in the search for superior progenies, based on agronomic variables obtained from early generation progeny of intraspecific progenies of peanuts (Arachis hypogaea L.) Four segregating populations were used, each consisting of 90 progenies, arranged in a randomized block design with three replicates, in which the best 30 progenies of each population were selected. The index of distance to the ideotype, used for the selection, was built from a non-real model cultivar that meets the requirements for traits main stem height (SH), early flowering (EF), number of pegs (NP), number of pods per plant (NPP), weight of 100 pods (WP100), number of seeds per plant, and weight 100 seed (WS100). It was observed that the selection index used was effective for differentiating progenies and promoting gains at a selection pressure of 33.33%. Gains were variable for the same traits in the different populations. The number of pods per plant, for example, ranged from 3.96% in the population 3 to 16.98% in the population 4. The analysis of diversity showed that progenies selected grouped differently, by principal coordinates analysis, which corroborates the ability of the index to form groups according to traits of interest. The groups formed revealed moderate variability by the diversity analysis by the Ward/MLM method.

Estimativas de parâmetros genéticos em linhagens de amendoim baseadas em descritores associados ao ginóforo

Genetic parameters of traits related to peanut pegs were assessed from F 2 lines carried out on two environments, in Pernambuco state - Brazil . Ninety lines and ancestors were evaluated in completely randomized block based on these traits: total number of pegs, pegs located at lower third of the plant, main axis height and number of pods per plant. Reproductive efficiency was also estimated based on number of pods per plant (NVP)/total number of pegs (NGT) and number of pods per plant (NVP)/pegs located at lower third of the plant (NGTI) rations. Variance components were estimated by Restricted Maximum Likelihood Method (REML) and the genotypic values were predicted by Best Linear Unbiased Prediction (BLUP). The heritability estimates were low and median for all traits. It was found that selection based on these traits has limited benefits on initial breeding. Genetic correlations were found between total number of pegs (NGT) x number of pods per plant (NVP) and pegs located at lower third of the plant (NGTI) x number of pods per plant (NVP). The traits total number of pegs (NGT) and pegs located at lower third of the plant (NGTI) could be used on further selection procedures focusing on pod productions.

Inoculation efficiency of Azospirillum brasilense on economising nitrogen fertiliser in landrace popcorn

Nitrogen is one of the nutrients most demandedby popcorn, and one that most increases production costs. Considering these factors, the aim of this study was to evaluate the effectiveness of inoculatingpopcorn seeds with Azospirillum brasilense together with four levels of nitrogen fertiliser, and its contribution to characteristics related to production. The experiment was carried out in the experimental area of the Centre for Agrarian Sciences and Biodiversity of the Federal University of Cariri, in Crato, in the State of Ceara. Eight treatments were evaluated with four replications, using an experimental design of randomised blocks in a 2x4 factorial scheme corresponding to the presence and absence of inoculation, and to four doses of nitrogen as top dressing. The following characteristics were evaluated: plant height, height of ear insertion, number of plants, number of lodged plants, number of broken plants, number of poorly husked ears, ear diameter, ear length, number of ears, number of diseased ears, number of infested ears, grain productivity, ear weight, mean 100-grain weight, and expansion capacity. There were significant differences for most of the characteristics under evaluation, with an increase of 17.18% in the number of ears and 10.78% in grain productivity, reducing the top dressing to 50 kg ha-1 in the presence of A. brasiliensi. These results demonstrate the potential for economisingnitrogen fertiliser in popcorn production under the soil and climate conditions of the Cariri region of the State of Ceara.

VARIABILIDADE GENOTÍPICA DE AMENDOIM EM RESPOSTA A ESTRESSE HÍDRICO BASEADA EM DESCRITORES BIOQUÍMICOS

Seven biochemical descriptors were used to estimate the genotypic variability of peanut in response to moderate water stress. Six genotypes, constituted by four lines and two cultivars, were grown in pots, each containing two plants. At 15 days after emergence (DAE), the treatment differentiation was carried out: Control-plants maintained with daily watering, and Stress-plants submitted to water stress by complete suspension of watering for 15 days. The experimental design was completely randomized with factorial scheme 6 x 2 (genotype x water treatments), with five replications. The biochemical variables evaluated were: catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), free proline, total carbohydrates, soluble proteins, and amino acids. Results obtained by biochemical analysis and estimation of genotypic variability indicated that proline is the most appropriate descriptor for selecting genotypes tolerant to water stress, which led to identification of L81V and L108V as promising lines for drought tolerance breeding program.