Dalmo Lopes de Siqueira

Gas exchange and chlorophyll fluorescence in four citrus rootstocks under aluminium stress

Summary A greenhouse experiment using nutritive solution was carried out to determine the effect of aluminium (AI) on several photosynthesis-related characteristics in Citrus limonia (‘Cravo’), Citrus volkameriana (‘Volkamer’), Citrus reshni (‘Cleopatra’), and Citrus sunki (‘Sunki’) seedlings. The effects of five AI concentrations (0, 50, 100, 200, and 400 μmol L -1 ) in the solution were determined. The lemon seedlings had the highest net photosynthesis in the absence of AI. The net photosynthesis decreased in the presence of AI in all the rootstocks, and the ‘Cravo’ lemon seedling was the most affected, with a decrease of 85% at the highest AI concentration evaluated. Stomatal conductance of water vapor (g s ) was not significantly affected in the lemon seedlings, but it was increased by the AI in the tangerine seedlings. The internal concentration of CO 2 (C i ) increased significantly in all the rootstocks with the increase in the AI concentration, but this increase did not result in higher net photosynthesis values. The greatest water use efficiency (WUE) in the absence of AI, was observed in the lemon seedlings. The WUE decreased in all rootstocks with the increase in the AI concentration in the nutritive solution, due to the decrease in the net photosynthesis and increase in the transpiration rate. One of the probable reasons for the reduction in the net photosynthesis was the structural damage to the thylakoids, which affected the photosynthetic transport of electrons, as indicated by the reduction of the ratio between variable fluorescence and initial fluorescence (F v /F 0 ).

Comprimento de estacas e parte do ramo na formação de mudas de aceroleira

The rhizogenic capacitity, sprouting and vigor of cuttings from barbados cherry (Malpighia emarginata D.C) were evaluated in greenhouse conditions at the EMBRAPA - National Center for Research of Tropical Agroindustry, Fortaleza-CE, from November 2000 to January 2001, aiming to identify the best branch part and size for cuttings preparation. The experiment was conducted in a completely randomized design, in a 3x3 factorial scheme, corresponding to three positions on the branch (apical, median and basal) and three length (10, 15 and 20 cm), with three replications composed by 10 cuttings each, and cultured on tubets of 288 cm3, filled wich a misture of organic matter (vermicompost) and carbonized rice husks (3:2 volumetric proportion), and cultivated in a greenhouse with intermittent mist. After 60 days were evaluated the percentage of surviving cuttings, rooted cuttings, roots and aerial part dry matter, number of leaves, not developed meristems, and number of new branches per cutting. Results indicated that vegetative propagation by cuttings of Barbados cherry is a feasible method, by using cuttings with 10 cm length, taken from the middle positions of the branch, and cultured under greenhouse conditions and intermittent mist.

Assessment of Nitrogenized Nutrition of Citrus Rootstocks Using Chlorophyll Concentrations in the Leaf

Abstract The objective of this study was to evaluate the nitrogen (N) nutrition in lemon tree rootstocks “Cravo” (Citrus limonia Osbeck) and “Volkameriano” (Citrus volkameriana Ten. e Pasq.) and mandarin tree rootstocks “Cleopatra” (Citrus reshni Hort. ex Tan.) and “Sunki” (Citrus sunki Hort. ex Tan.), using the chlorophyll concentration in the rootstock leaves, grown in 3.0 dm3 capacity container in a greenhouse. Nitrogen was added to the lemon tree substrate at 0, 158, 316, 474, and 632 mg/dm3, and 0, 193, 386, 579, and 772 mg/dm3 were added to the mandarin trees. These N quantities were divided into 20 urea applications for the lemon trees and 24 applications for the mandarin trees during the experiment. The experiment consisted of a factorial arrangement (4 × 5), carried out in a randomized block design, with three replications. The experimental unit consisted of four containers, with one plant per container. The chlorophyll concentration, measured by the Arnon standard method and by the SPAD‐502 portable apparatus, were affected by the N. In general, the rootstocks presented little variation in the chlorophyll concentration measured in the leaves. These values were positively correlated with the growth characteristics and N concentration in the leaves, indicating that N can be monitored using such determinations.

Genetic Diversity of 'Uba ´' Mango Tree Using ISSR Markers

In this study, the genetic diversity of ‘Ubá’ mango trees cultivated at the Zona da Mata of Minas Gerais State, Brazil, was assessed, to identify whether there is variability in the plants grown in the region, justifying the mass selection as a breeding method. We used 102 accessions. Leaves were collected for extraction of genomic DNA, which was amplified with nine ISSR primers. The data obtained by the analysis of electrophoretic patterns were arranged in a binary matrix, considering 0 for the absence and 1 for the presence of bands. Based on these data, we performed the analysis of genetic dissimilarity and carried out the cluster analysis by the methods of Tocher and graphical dispersion. The most similar accessions are 144 and 150, both coming from Ubá, while the most divergent ones are 29 and 97, from Visconde do Rio Branco. The grouping by the Tocher method separated the accessions into six groups, 94.1% of which were allocated in the first group and showed that there is no separation of accessions depending on the sampling sites. The 3D scatter plot reinforces this conclusion. There is genetic variability among the accessions of ‘Ubá’ mango tree evaluated. Therefore, it is possible to make mass selection in open-pollinated populations.

Características físicas do maracujá-azedo em função do genótipo e massa do fruto

Physical traits of the fruits of several progenies were evaluated and the correlations among them were studied. The fruits, originated of natural pollination, were picked up at the harvest stage and classified in two weight classes: 1 -180 to 230 g and 2 -80 to 130 g. of each class were sampled two fruits to evaluate the mass of the fruit (g), mass of the skin (g), mass of the seeds (g), mass of the juice (g), longitudinal length and equatorial diameter of the fruit (mm), thickness of the skin (mm), number of seeds, juice weight per seed (g), ratio skin thickness/ fruit ray, ratio longitudinal length/equatorial diameter, juice content (%), skin ratio (%), seed ratio (%) and residues (%). The thickness of the skin varied among the mass classes, indicating that skin evaluation of different fruit sizes can lead to misunderstandings and the evaluation of the progenies.

Estimativas de tamanho de parcelas para avaliação de descritores fenotípicos em bananeira

The aim of this work was to estimate the adequate size of experimental plots, for the evaluation of phenotypic descriptors in banana, from a trial of uniformity with the cultivar Tropical, in the spacing of 3x2 m, in a useful area with nine rows of 40 plants. The following variables were evaluated: plant height; pseudostem perimeter; number of emitted suckers and number live leaves, during flowering and at harvest; weight of the bunch and the hands; number of hands and fruits; weight of the second hand; weight, length and diameter of the fruit, in two cycles of production. The plants, considered the basic units, were combined to form various sizes of plots. The data were submitted to the analysis of variance in the hierarchical model. Plot size was estimated by the methods of maximum curvature, modified maximum curvature and comparison of variances. Heterogeneity index of the soil and the detectable difference among treatments mean were determined. The variability increased between cycles with reflexes in the estimates of the plot sizes, which varied with the method used, the variable evaluated and the production cycle. The modified maximum curvature method presents more adjusted estimates. Plots with six basic units (36 m2) are appropriate to evaluate with precision the phenotypic descriptors in the bananas.

Seleção de progênies de maracujazeiro-amarelo vigorosas e resistentes à verrugose (Cladosporium cladosporioides)

The scab (Cladosporium cladosporioides) is a harmful disease of the yellow passion fruit vine (Passiflora edulis f. flavicarpa). It attacks young tissues of leaves, branches, flowers and fruits, causing necrosis at the infected site. Three passionfruit cultivars and 39 half-sibling progenies were evaluated for plant vigor and scab incidence at the Department of Phytotechnics of the Federal University of Vicosa, in Brazil, in February 2003. A randomized block design with three replication and four plants per parcel were aplayed. Plant vigor and incidence of scab were evaluated according to a scale varying from one (less vigor or low incidence) to five (higher vigor or higher incidence). The selection was simulated independently for resistance to scab and plant vigor and by means of two selection indexes involving the two characters. The selection index 2, with weight -2: 1 for resistance to scab and plant vigor, respectively, gave the most balanced estimated selection gains, around 10% for each one of the characters, and was adopted in this work. Heritabilities of 44,68% and 56,53% were estimated for resistance to scab and plant vigor, respectively. The progenies 2, 3, 6, 7, 19, 20, 22, 27, 32 and 36 were selected based in the selection index 2.

Método de comparação de modelos de regressão não-lineares em bananeiras

The use of models to describe the growths of plants has a wide application in the agronomy and cattle research. In this type of research, two problems are often present: to find the model that shows more information, which is best fitted to the biologic phenomenon and identifying curves that are statistically equal. Thus, the objective of the present work was to compare the quality adjustments models of non linear regression in the description of growth and to compare the curves from this best model in relation to different treatments. Data from an experiment installed in a factorial arrangement 2x5, in a randomized design of blocks with eight repetitions were used. The levels of treatments were constituted by two banana tree cultivars and five doses of a growth regulator. The cluster analysis was used with three statistics that allowed access to the ideal number of groups. In the comparison of growth models, the superiority of the logistic model was observed. For comparison of treatments, it was verified that the cluster method analysis with the changes proposed allowed to detect three groups of treatments, that are similar to the biologic behavior.

Desenvolvimento dos frutos de lulo (Solanum quitoense LAM), em Viçosa-MG

The lulo is a tropical and exotic fruit, originating in the Andes is orange when ripe, and is a globose berry, resembling a tomato, the epicarp is thick and leathery, its pulp is light green, sticky, sour and juicy, containing many seeds. The objective of this study was to monitor the physical, chemical and physiological characteristic changes occurring during lulo fruit development, from anthesis to the full plant maturation. The fruits were harvested in the orchard of the Federal University of Vicosa and the analysis performed in the Laboratory of Fruits Analysis, from the Plant Science Department. The reproductive cycle of lulo lasted 95 days. Fruits development was divided into three phases. The first phase was up to 7.39 days after anthesis (DAA), being characterized by high respiratory rates, probably due to the intense cell multiplication and the pericarp showed light green color. The second phase occurred from 7.39 DAA to 57,63 DAA, being characterized by maximum rates of increase in dimensions of the fresh and dry fruit, the pericarp developed an intense green color and respiratory rates increased until 45 DAA and remained stable until 52 DAA. The third and final development phase occurred from 57.63 DAA to 95.00 DAA, the last day of evaluations. This phase was characterized by dimensions stabilization and accumulation of fresh mass. In this period, the climacteric rise (from 52 to 59 DAA) occurred. The respiratory climacteric occurred at 66 DAA, with peak production of CO2 of 110,99 mg CO2 kg-1 h-1. The post-climacteric was between 73 and 95 DAA, when soluble solids increased and acidity and vitamin C from the pulp decreased. At this stage, the pericarp of the fruits showed orange coloration.

Propagação por estaquia dos maracujazeiros doce (Passiflora alata Dryand.) e amarelo (P. edulis f. flavicarpa O. Deg.)

The vegetative propagation by cutting is one of the techniques that allows to obtain uniform orchards of passion fruit, as well as of rootstocks that increases productivity and, or resistance to pests and diseases. Even so, the information on the best cutting type to be used are not conclusive. With the objective of evaluating the effects of several types of cuttings, as material for seedling formation of passion fruit, an experiment was carried out in the Fruit Science Sector of the Federal University of Vicosa. The factors in study were apical, medium and basal cuttings of the last growth of Passiflora alata Dryand. and P. edulis f. flavicarpa O. Deg. Fifty days after the beginning of the experiment, it were evaluated the rooting percent, the number of roots, the length of the largest root, the mass of dry matter of the root system, the length and the area of the root system, and the mass of dry matter of the shoot. Cuttings of the basal and medium positions presented bigger rooting potential and larger growth of the root system. Although they have not differed with relationship to the rooting percent and the number of roots, Passiflora alata presented more vigorous root system than P. edulis f. flavicarpa.