José Nildo Tabosa

Salt stress in maize seedlings. Part I. Growth analysis.

The work was performed in the greenhouse, aiming to evaluate the effect of salt stress on maize cultivars differing in salinity tolerance. Data were carried out on 2 x 5 factorial arrangement with two maize cultivars (P-3051 and BR-5011) and five sodium chloride levels in nutritive solution (0, 25, 50, 75 or 100 mol m -3 ). The shoot dry matter, root dry matter, shoot to root ratio, leaf area (LA), absolute growth rate (AGR), relative growth rate (RGR), net assimilation rate (NAR) and leaf area ratio (LAR) were analyzed. The salt stress affected all studied variables, except LAR. The shoot dry matter, root dry matter, LA, AGR and RGR were the best parameters to express the salt stress effect on maize plants. On the other hand, the shoot to root ratio, NAR and the LAR were the best parameters to express differences between cultivars regarding their tolerance or sensitivity to salt stress.

Estresse salino em plântulas de milho: parte II distribuição dos macronutrientes catiônicos e suas relações com sódio

The work was performed in the greenhouse, aiming to evaluate the effect of salt stress on distribution of nutrients in different parts of maize cultivars differing in their tolerance to salinity. The experiment was carried out on 2 x 5 factorial arrangement with two maize cultivars (P-3051 and BR-5011) and five sodium chloride levels in nutrient solution (0, 25, 50, 75 or 100 mol m-3). Salt stress increased Na+ content and decreased K+ content in all plant parts. Na+ content was higher in stalk and sheath than in leaf blade tissue. Ca++ content decreased in root, stalk and leaf blade while Mg++ content decreased only in root and in stalk tissue. Root Ca++ content in the cultivar P-3051 under 100 mol m-3 NaCl was 60% higher than in the cultivar BR-5011. The salt treatment increased Na+/K+, Na+/Ca++ and Na+/Mg++ ratios in all plant parts, and the increment was higher in the P-3051 than in the BR-5011 cultivar.

Coeficiente de repetibilidade e parâmetros genéticos em capim-elefante

The objective of this work was to determine the coefficients of repeatability of morphophysiological traits in elephant grass (Pennisetum spp.) genotypes, from data obtained during six evaluation cycles. The minimum number of measurements and genetic parameters were estimated. The experiment design was a randomized complete block, in a split‑plot arrangement, with four N levels (control, 30, 60, and 90 kg ha‑1 per cut) and 16 Pennisetum genotypes (11 interspecific hybrids and five cultivars). The cycles consisted of evaluations in 2010 (4/21, 7/19, and 9/28) and 2011 (1/6, 4/7, and 8/3). The coefficients of repeatability were of medium‑high magnitude for all variables, indicating that there was regularity between repeated measures. For the variables forage mass, plant height, leaf length and width, stem diameter, leaf chlorosis and area index, three cycles of evaluation are enough to reach R2 of 90% by principal component analysis. For internode length, the minimal of seven evaluations is necessary to predict the true value of genotypes. The genetic parameters of the variables forage mass, leaf length and width, stem diameter and leaf chlorosis are of high magnitude, favoring the selection of superior Pennisetum genotypes.

Desenvolvimento inicial do milho submetido à adubação com manipueira

This research aimed to evaluate the effect of cassava wastewater fertilization on maize growth. The experiment was carried out under greenhouse conditions at the Federal Rural University of Pernambuco (Brazil). Treatments were assigned in a factorial arrangement 5 x 3, being 5 cassava wastewater doses: 0, 12.6, 25.2, 50.4 and 75.6 m3 ha-1 and 3 harvest ages: 20, 40, and 52 days after germination (DAG), in a completely randomized design, with four replications. A hybrid of forage maize (AG 1051) was used, keeping one plant in a 20 L pot. The variables evaluated were: plant height, stalk diameter, number of leaves, dry and fresh matter of leaves and stalks. The dose equivalent to 63 m3 ha-1 provided the highest gain in stalk diameter, number of leaves, dry and fresh matter of leaves; while the dose equivalent to 75.63 m3 ha-1 provided significant increase in the other evaluated phenological parameters. Cassava wastewater presented as a useful fertilization source for maize crop, however responses depended on utilization of appropriated cassava wastewater doses.

Selection of plant growth-promoting bacteria in sweet sorghum ( Sorghum bicolor (L.) Moench) under the effects of salinity

Background Sorghum, a grassy non-halophyte, it is both drought and salinity tolerant, and is considered a promising crop for semiarid regions. During the last 20 years, its culture has expanded in Brazilian production by 780%, reaching 1,928,970 tons in 2009 [1]. Salinization of the soil and lack of rain are increasing constraints in semiarid regions. They predominate in northeastern Brazil. This has helped limit the production of plant biomass, which is the basis of agricultural activity. The advantages of sorghum in these conditions can be improved still further by using plant growth-promoting bacteria (PGPB) for the biological processes of nitrogen fixation, and hormone production, as well as others [2]. Endophytic bacteria can secrete up to one half of the nitrogen they fix, and plants may then assimilate the nitrogen efficiently [3]. Inoculation with Azotobacter chroococcum has been shown to attenuate stress in maize grown in saline soil [4]. In this study, we evaluated the action of PGPB on a “Wray” saccharine variety with low salinity tolerance.

Identificação de fontes de resistência de milho à Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae) em campo

The objective of this work was to identify sources of resistance to Spodoptera frugiperda (J. E. Smith) in six corn cultivars (CMS-22, CMS-35, AG-106, Dina-70, AG-510 and CMS-36) which were tested under field conditions using a complete randomized block design with four replications. The following parameters were observed: a) foliar damage, obtained through a visual note scale; b) larvae survival, weigth and length, measured 10 days after artificial plant infestation. There were significant statistical differences (P=0.05) among cultivars only in relation to foliar damage, being AG 510 the most resistant cultivar with an average damage of 5.41. The most susceptible cultivars were CMS 35 and AG 106 which had an average damage of 8.38 and 7.85 respectively. Significant linear correlations (P=0.01) were found between foliar damage and larvae weigth; foliar damage and larvae length; and larvae weigth and larvae length, indicating the possibility of utilization of these parameters to evaluate resistance of corn cultivars to S. frugiperda.

Identificação de fontes de resistência em cultivares de milho à spodoptera frugiperda (J. E. Smith, 1797) em casa-de-vegetação

Two experiments were conducted in a greenhouse, with the objective of identifying sources of resistance in 15 corn cultivars to Spodoptera frugiperda. The following cultivars were utilized CMS-35 , CMS-36, Dina-70, Cargill-525, Pioneer-3210, Pioneer-6875, BR-201, BR-451, AG-106, AG-510, CMS-22, Contimax-322, BR-201, Jatina C3 Anao, Cargill-511 e BR-106. When the plants had 8 to 10 leaves they were infested with 30 newly ecloded larvae per plant. Damage evaluation was made 10 to 14 days after infestation, in both experiments, using a visual note scale from 0 to 9. There were no statistical differences among cultivars for the parameters evaluated damage, weight, length and survival larvae. Nevertheless a significant linear correlation was found between weigth x larvae length (n = 0,7776, P = 0,01), demonstrating that these parameters can be utilized in the study of corn resistence to S. frugiperda.