Genetic variability of Dactylopius opuntiae (Hemiptera, Dactylopiidae) on forage cactus in northeast Brazil.

The carmine cochineal Dactylopius opuntiae is a key pest in productive fields of forage cactus in Pernambuco, Brazil. Species identification by means of molecular markers assists in understanding the genetic profile, underpins morphological characterization, and supports the monitoring of populations in integrated management programs designed to control this pest. We evaluated the genetic variability of natural populations of D. opuntiae. Genetic variability was analyzed with ISSR and RAPD primers in 24 populations from 12 municipalities of Pernambuco State in Brazil. Morphological characterization confirmed that D. opuntiae was the only cochineal species present in all samples. Nine ISSR primers and six RAPD produced a total of 62 and 58 polymorphic fragments, respectively. Both types of markers showed an average genetic similarity of 80% regardless of the geographic origin of samples. The low genetic variability demonstrates a high degree of relatedness among these D. opuntiae populations.

Salt stress response and proline accumulation in Brachiaria humidicola plants with and without mycorrhizal inoculation.

The work was carried out to investigate the effects of different concentrations of NaCl on Brachiaria humidicola Rendle in the presence and absence of Glomus etunicatum Becker and Gerdemann, as well as to evaluate some growth parameters and the accumulation of free proline in the plant leaves. The soil used was a Neosoil Fluvic Eutrophic with pH of 6.5, organic matter, 12.8 g kg-1 and soil texture, sandy loam, in which Brachiaria humidicola Rendle cv. 409 was grown. Five NaCl concentrations were tested 0; 0.22; 1.09; 1.96 and 2.84 g. kg-1 of soil, whose electrical conductivity (EC) were 2.22; 4.00; 8.13; 12.53 and 16.50 dS m-1, respectively. Brachiaria humidicola showed salt tolerance when submitted to an EC of 4 dS m-1. There was a reduction of leaf area, dry matter of shoots and roots for the soil treatments beyond EC at 8 dS m-1. Free proline content in the leaves increased together with the increase in soil salinity (EC at 8 dS m-1) demonstrating that plants submitted to EC of 2 and 4 dS m-1 were less affected by salt stress, and consequently accumulated less proline in the leaves. Root colonization was not affected by the increase of NaCl dosage in the soil.

Salt stress response and proline accumulation in Brachiaria humidicola plants with and without mycorrhizal inoculation

The work was carried out to investigate the effects of different concentrations of NaCl on Brachiaria humidicola Rendle in the presence and absence of Glomus etunicatum Becker and Gerdemann, as well as to evaluate some growth parameters and the accumulation of free proline in the plant leaves. The soil used was a Neosoil Fluvic Eutrophic with pH of 6.5, organic matter, 12.8 g kg-1 and soil texture, sandy loam, in which Brachiaria humidicola Rendle cv. 409 was grown. Five NaCl concentrations were tested 0; 0.22; 1.09; 1.96 and 2.84 g. kg-1 of soil, whose electrical conductivity (EC) were 2.22; 4.00; 8.13; 12.53 and 16.50 dS m-1, respectively. Brachiaria humidicola showed salt tolerance when submitted to an EC of 4 dS m-1. There was a reduction of leaf area, dry matter of shoots and roots for the soil treatments beyond EC at 8 dS m-1. Free proline content in the leaves increased together with the increase in soil salinity (EC at 8 dS m-1) demonstrating that plants submitted to EC of 2 and 4 dS m-1 were less affected by salt stress, and consequently accumulated less proline in the leaves. Root colonization was not affected by the increase of NaCl dosage in the soil.

Salt stress response and proline accumulation in Brachiaria humidicola plants with and without mycorrhizal inoculation

The work was carried out to investigate the effects of different concentrations of NaCl on Brachiaria humidicola Rendle in the presence and absence of Glomus etunicatum Becker and Gerdemann, as well as to evaluate some growth parameters and the accumulation of free proline in the plant leaves. The soil used was a Neosoil Fluvic Eutrophic with pH of 6.5, organic matter, 12.8 g kg-1 and soil texture, sandy loam, in which Brachiaria humidicola Rendle cv. 409 was grown. Five NaCl concentrations were tested 0; 0.22; 1.09; 1.96 and 2.84 g. kg-1 of soil, whose electrical conductivity (EC) were 2.22; 4.00; 8.13; 12.53 and 16.50 dS m-1, respectively. Brachiaria humidicola showed salt tolerance when submitted to an EC of 4 dS m-1. There was a reduction of leaf area, dry matter of shoots and roots for the soil treatments beyond EC at 8 dS m-1. Free proline content in the leaves increased together with the increase in soil salinity (EC at 8 dS m-1) demonstrating that plants submitted to EC of 2 and 4 dS m-1 were less affected by salt stress, and consequently accumulated less proline in the leaves. Root colonization was not affected by the increase of NaCl dosage in the soil.(AU)

Salt stress response and proline accumulation in Brachiaria humidicola plants with and without mycorrhizal inoculation.

The work was carried out to investigate the effects of different concentrations of NaCl on Brachiaria humidicola Rendle in the presence and absence of Glomus etunicatum Becker and Gerdemann, as well as to evaluate some growth parameters and the accumulation of free proline in the plant leaves. The soil used was a Neosoil Fluvic Eutrophic with pH of 6.5, organic matter, 12.8 g kg-1 and soil texture, sandy loam, in which Brachiaria humidicola Rendle cv. 409 was grown. Five NaCl concentrations were tested 0; 0.22; 1.09; 1.96 and 2.84 g. kg-1 of soil, whose electrical conductivity (EC) were 2.22; 4.00; 8.13; 12.53 and 16.50 dS m-1, respectively. Brachiaria humidicola showed salt tolerance when submitted to an EC of 4 dS m-1. There was a reduction of leaf area, dry matter of shoots and roots for the soil treatments beyond EC at 8 dS m-1. Free proline content in the leaves increased together with the increase in soil salinity (EC at 8 dS m-1) demonstrating that plants submitted to EC of 2 and 4 dS m-1 were less affected by salt stress, and consequently accumulated less proline in the leaves. Root colonization was not affected by the increase of NaCl dosage in the soil.

Nitrate levels and stages of growth in hypernodulating mutants pf Lupinus Albus. I. N2 fixation potential

This work aimed to evaluate physiological parameters, nodulation response and N2 fixation rate in mutants of Lupinus albus in comparison with the standard Multolupa cultivar. Two nitrate levels (0 and 5mM) and two evaluation periods (7 and 10 weeks) were used. Significant differences were observed among genotypes, in relation to fresh nodule weight, nitrate levels and growth stages. The overall average for nitrate level differed between them where 5mM severely inhibieted the number of nodules, reaching a 49.5 (per cent) reduction in relation to treatment without nitrate. There were no behaviour differences among genotypes, nor among evaluation periods. Although the level of nitrate did not influence the production of shoot dry matter in relation to the average among levels applied, the L-135 genotype, being an inefficient mutant, reached very low values. There were no significant differences in electron allocation coefficient (EAC) among nitrate levels, nor among genotypes studied. However , the evaluation periods revealed differences, where the EAC for the seventh week had a higher value than that for the tenth week, when a 5mM aplication was evaluated. The N2 fixation rate (N2FIX) showed the existence of the nitrate interference in fixation, given that the application of 5mM severely reduced. However, there were no differences among the genotypes and it was noted that the fixation rate was much higher in those that received nitrate. The L-88 and L-62 genotypes were the ones that have shown best adaptability in this experiment, thus being able to be recommended for new studies with higher nitrate levels and different evaluation periods. The nitrate (5mM) interferes in the nitrogen fixation rate, given that all the genotypes were affected by the level applied.