Scielo RSS <![CDATA[Chilean journal of agricultural research]]> http://www.scielo.cl/rss.php?pid=0718-583920140004&lang=pt vol. 74 num. 4 lang. pt <![CDATA[SciELO Logo]]> http://www.scielo.cl/img/en/fbpelogp.gif http://www.scielo.cl <![CDATA[<b>Biochemical and physiological characterization of three rice cultivars under different daytime temperature conditions</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400001&lng=pt&nrm=iso&tlng=pt Heat stress due to high daytime temperatures is one of the main limiting factors in rice (Oryza sativa L.) yield in Colombia. Thus, the objective of the present research was to analyze the effect of three different daytime temperatures (25, 35, and 40 °C) on the physiological responses of three Colombian rice cultivars (F60, F733, and F473), thereby contributing to the knowledge of rice acclimation mechanisms. For 10 d, eight plants of each of the three cultivars were subjected daily to 5 h periods of 35 and 40 °C. The control treatment corresponded to normal growth conditions (25 °C). Thermal stress was assessed based on a series of physiological and biochemical parameters. The 35 °C treatment produced photosynthetic and respiratory differences in all three cultivars. At 40 °C, 'F60' displayed the lowest photosynthetic rate and the highest respiratory rate. Although this cultivar experienced particularly strong electrolyte leakage and changes in proline when subjected to the high-temperature treatments, similar trends were observed in 'F733' and 'F473'. At 40 °C, the concentration of malondialdehyde (MDA) was lower in 'F473' than in the other cultivars. These results may explain the poor agronomic performance of 'F60' in the field under daytime heat stress. The methodologies employed in the present work may be useful in Colombian rice breeding programs, particularly for the selection of heat-tolerant breeding stocks. <![CDATA[<b>Dry matter and water dynamics of wheat grains in response to source reduction at different phases of grain filling</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400002&lng=pt&nrm=iso&tlng=pt Agreement that wheat (Triticum aestivum L.) is scarcely limited by source of assimilates during grain fill has not been confirmed when source was drastically decrease in high yield potential environments. Dry matter (DM) and water dynamics of growing grains being possibly able to explain grain weight (GW) responses to source-sink ratios (S-Sratios) in these conditions. Objectives were to evaluate response of GW to S-Sratios at different phases during grain fill, and relationship between DM and grain water content in response to different S-Sratios. Wheat was sown at field conditions during 20042005 and 2005-2006 growing seasons. Four S-Sratios were assessed: Control without S-Sratios modification (C), S-Sratios from anthesis (At) +12 d to physiological maturity (ShAll), S-Sratios from At +12 d to first half of grain fill (Sh1st) and from second half of grain fill to maturity (Sh2nd). Thousand grain weight (TGW), GW at individual positions (IGW), stabilized grain water content (SGWC) and grain filling rate (GFR) were measured. TGW sensitivity to S-Sratios varied according to length of treatment and its timing, i.e. ShAll, Sh1st, and Sh2nd treatments reduced TGW by 48%, 26%, and 22%, respectively. These reductions were little higher when IGW were evaluated in ShAll (i.e. 53%) and Sh1st (i.e. 33%) treatments and lower in Sh2nd (i.e. 12%). SGWC sensitivity was lower than that of IGW across S-Sratios (e.g. SIiau 27%, Shust 22%, and Sh2nd 5%). However, close association between IGW and SGWC (R² = 0.78, p < 0.001) and between GFR and SGWC (R² = 0.98, p ≤ 0.001) was found regardless of S-Sratios and seasons <![CDATA[<b>Fatty acids and physiological quality of tomatillo (<i>Physalis philadelphica </i>Lam.) seed during natural ageing</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400003&lng=pt&nrm=iso&tlng=pt In México, 44 thousand hectares are planted with tomatillo or husk tomato (Physalis philadelphica Lam.), which occupies fourth place among the country's vegetable species. However, research on this species is scarce, especially that related to the process of seed deterioration. We studied the effects of deterioration in tomatillo seed, var. CHF1-Chapingo, stored from 2-mo up to 7 yr with no climate control, 18.2 ± 5 °C and 41 ± 10% relative humidity, on physiological and biochemical variables during germination. It was found that germination, vigor, and respiratory activity decrease significantly from the first year of storage; thus, after 7 yr, germination and vigor decreased 99%, and respiratory activity of seed after 48 h imbibition decreased 78%. Linoleic acid (unsaturated) content correlated positively with germination (R = 0.78**) and with speed of radicle emergence (R = 0.79**). Germination correlated with speed of radicle emergence (R = 0.99**) and with respiratory activity after 48 h of imbibition (R = 0.79**). Both respiratory activity and fatty acid content are involved in natural deterioration of tomatillo seed. <![CDATA[<b>Cacao in México</b>: <b>Restrictive factors and productivity levels</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400004&lng=pt&nrm=iso&tlng=pt Cacao (Theobroma cacao L.) represents one of the most important agricultural crops of the humid Mexican tropics. In the last 10 yr, approximately 23.000 t of this grain were no longer produced per cycle. The objective of this study was to identify characteristics and factors that restrict production in the states of Tabasco and Chiapas. A survey was applied to obtain information about 184 producers and their plantations by two-stage sampling. Descriptive statistics were calculated and multilevel models were adjusted to analyze the information. Results show that there are differences (P < 0.05) in cacao yield between municipalities (380 kg ha-1 + u,o j is the estimated residual for each municipality). Crop productivity levels are higher in the state of Tabasco than in Chiapas (644 and 344 kg ha-1, respectively). Incidence of frosty pod rot of cacoa, also known as moniliasis, induced by Moniliophthora roreri [(Cif) H.C. Evans, Stalpers, Samson & Benny 1978] is significantly greater (P < 0.05) in the state of Chiapas (60%) than in Tabasco (48%).Producers who carry out more crop management practices increase yields and decrease the pathogen's impact on their plantations. Results suggest the need to apply differentiated public policies to promote production within each region or municipality. <![CDATA[<b>The economic impacts of climate change on the Chilean agricultural sector</b>: <b>A non-linear agricultural supply model</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400005&lng=pt&nrm=iso&tlng=pt Agriculture could be one of the most vulnerable economic sectors to the impacts of climate change in the coming decades, with impacts threatening agricultural production in general and food security in particular. Within this context, climate change will impose a challenge to policy makers, especially in those countries that based their development on primary sectors. In this paper we present a non-linear agricultural supply model for the analysis of the economic impacts of changes in crop yields due to climate change. The model accounts for uncertainty through the use of Monte Carlo simulations about crop yields. According to our results, climate change impacts on the Chilean agricultural sector are widespread, with considerable distributional consequences across regions, and with fruits producers being worst-off than crops producers. In general, the results reported here are consistent with those reported by previous studies showing large economic impacts on the northern zone. However, our model does not simulate remarkable economic consequences at the country level as previous studies did. <![CDATA[<b>Access to credit and determinants of technical inefficiency of specialized smallholder farmers in Chile</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400006&lng=pt&nrm=iso&tlng=pt Access to credit and credit constraint are critical determinants of competitiveness in agriculture; they have an impact on the technical efficiency of farms. The objective of this study was to analyze how credit variables influence the technical efficiency of two groups of specialized smallholder farmers in Chile. The translog stochastic production frontier model was used to predict the level of farm technical efficiency by the maximum likelihood method. Based on 2004 data, production functions and technical inefficiency score were estimated for 109 livestock and 342 crop producers. Results showed that the mean technical efficiency was 89% and 78% for crop and livestock producers, respectively. Technical efficiency increased with the decreasing use of inputs, dependence on on-farm income, farmer education, family size, and age of the head of household. Credit volume had a significant impact by increasing and decreasing efficiency in crop and livestock production, respectively. Correspondingly, credit-constrained farmers were less efficient in crop production and more efficient in livestock production. For livestock producers, credit volume and credit constraints were found to be endogenous to technical efficiency. A possible explanation is the organization of public support for small livestock producers in Chile, which provides lenders with information about individual livestock producers. Correcting for this endogeneity did not lead to qualitatively different results, but it did influence point estimates of parameters in the production function and inefficiency models, suggesting that it is important to test for endogeneity in the variables used to model inefficiency effects. <![CDATA[<b>Insecticidal activity of <i>Laurelia sempervirens </i>(Ruiz & Pav.) Tul. essential oil against <i>Sitophilus zeamais </i>Motschulsky</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400007&lng=pt&nrm=iso&tlng=pt The maize weevil Sitophilus zeamais Motschulsky is a worldwide key pest of stored products. Usually contact insecticides or fumigants are used against it, but problems as toxic residues, human intoxications, and resistance have triggered the search for alternative control methods as the use of essential oils. The objective of this research was to assess under laboratory conditions, the insecticidal properties of Laurelia sempervirens (Ruiz & Pav.) Tul. essential oil against S. zeamais. In contact toxicity bioassay assessed treatments were 0 (control), 1.25, 2.5, 5.0, 10, 20, and 40 mL essential oil kg-1 grain and 0 (control), 25, 50, 75, 100, 125, 150, and 175 μL essential oil L-1 air in fumigant toxicity tests. The highest toxicity by contact activity was reached by concentrations higher than 10 mL essential oil kg-1 grain (100% mortality). The same treatments totally inhibit F1. The dose of 175 μL essential oil L-1 air showed a significant toxicity by fumigant activity causing 72.5% of dead insects. The other treatments did not surpass 5% mortality. In offspring effect (F1) bioassay, all treatments had an insect emergence significantly lower than the control but concentrations equal or higher than 10 mL essential oil kg-1 grain prevented the emergence of F1 during the 7 wk of bioassay. The residual effect of contact toxicity remained by 15 d. The treatments based on essential oil lead to a weight grain loss lower than control and germination was not affected. All assessed treatments showed repellent effect. The essential oil of L. sempervirens has promissory perspectives to maize weevil control. <![CDATA[<b>Complete control of <i>Penicillium expansum </i>on apple fruit using a combination of antagonistic yeast <i>Candida oleophila</i></b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400008&lng=pt&nrm=iso&tlng=pt Three Candida oleophila strains (L06, L07 smooth, and L07 rough) were evaluated in vivo and in vitro as biocontrol agents against Penicillium expansum on postharvest 'Golden Delicious' apples (Malus domestica Borkh.) in Chihuahua, Mexico. The in vivo and in vitro activity of exo-β-1,3-glucanase was measured as a possible biocontrol mode of action for C. oleophila. Mean disease incidence caused by P. expansum was 0.3% for apples treated with fludioxonil + ciprodinil, which were used as a positive control, and 1% for fruits treated with a combination of the three C. oleophila strains; the effects of these treatments were significantly equivalent. Disease incidence in control apples was 39% and was significantly different from the other treatments. The in vivo exo-β-1,3-glucanase activity began at 24 h and peaked at 72 and 96 h for all treatments. Strain L06 had the highest activity (7.96 nKat) and a specific activity of 2.92 nKat μg-1. Candida albicans had the lowest activity (2.83 nKat) and a specific activity of 0.67 nKat ug-1. The highest in vitro activity was for C. albicans (85.03 nKat) and the lowest for strain L06 (78.2 nKat). Significant differences in both in vivo and in vitro enzymatic activity were observed between strain L06 and C. albicans. Polynomial regression analysis (R² = 0.96 in vitro and 0.68 in vivo) indicated that increased enzymatic activity was associated with reduced fruit disease incidence. The production of exo-β-1,3-glucanase by C. oleophila is a possible mode of action for the efficient biocontrol of P. expansum on postharvest apples. <![CDATA[<b>Estimating grain yield losses caused by septoria leaf blotch on durum wheat in Tunisia</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400009&lng=pt&nrm=iso&tlng=pt Septoria leaf blotch (SLB), caused by Zymoseptoria tritici (Desm.) Quaedvlieg & Crous, 2011 (teleomorph: Mycosphaerella graminicola (Fuckel) J. Schrot.), is an important wheat disease in the Mediterranean region. In Tunisia, SLB has become a major disease of durum wheat (Triticum turgidum L. subsp. durum [Desf.] Husn.) particularly during favorable growing seasons where significant yield losses and increase of fungicides use were recorded over the last three decades. The objectives of this study were to evaluate the effect of SLB severity on grain yield of new elite durum wheat breeding lines and to measure the relative effect of fungicide control on grain yield. Experiments were conducted during 2007-2008 and 2008-2009 cropping seasons. A set of 800 breeding lines were screened for reaction to SLB under natural infection at Beja research station. To estimate the disease effect, correlation between disease severity at early grain filling stage and grain yield was performed. Results showed that susceptible varieties yield was significantly reduced by SLB. Average yield reduction was as high as 384 and 325 kg ha-1 for every increment in disease severity on a 0-9 scale in both seasons, respectively. A negative correlation coefficient varied between -0.61 and -0.66 in both seasons. Treated and untreated trials conducted during 2008-2009 and 2009-2010 showed that yield of treated plots increased by 50% on the commonly cultivated susceptible varieties. The results of this investigation suggested that septoria incidence is related to large grain yield losses particularly on susceptible high yielding cultivars. However, appropriate fungicide application at booting growth stage could be beneficial for farmers. The development and use of more effective fungicide could be sought to alleviate the disease effects and therefore could be considered as a part of the integrated pest management and responsible use strategy on septoria leaf blotch in Tunisia. <![CDATA[<b>Effect of picloram herbicide on physiological responses of <i>Eupatorium adenophorum </i>Spreng</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400010&lng=pt&nrm=iso&tlng=pt Eupatorium adenophorum Spreng., a major invasive weed in southwestern China, has caused great economic losses. In order to find a new herbicide to control E. adenophorum, experiments were conducted to study its physiological and biochemical responses to low and high doses of picloram herbicide (4-amino-3,5,6-trichloropyridine-2-carboxylic acid). Electrolyte leakage, malondialdehyde, and free proline were stimulated by picloram, showing a remarkably increase (p < 0.05) with high herbicide concentration (60, 120, and 240 g ai ha-1). The treated plants exhibited lower osmotic adjustment capacity, high dosage lipid peroxide levels and more free-proline accumulation. It was found that low doses (12 and 24 g ai ha-1) of picloram initially increased catalase, peroxidase, superoxide dismutases and protein, but these indicators decreased (p < 0.05) with the increase of treating time (after 3 d) and dose (120 and 240 g ai ha-1). In addition, the structures of chloroplasts and mitochondria were seriously deformed. These results indicated E. adenophorum can improve its herbicide-tolerance by increasing the antioxidative system activity at the initial period of low picloram stress. However, this protective function disappeared with increasing of treating time and picloram dosage. Eupatorium adenophorum responded differently to low and high concentrations of picloram and ultrastructural changes are an important cause of death in E. adenophorum. <![CDATA[<b>Propolis or cashew and castor oils effects on composition of <i>Longissimus </i>muscle of crossbred bulls finished in feedlot</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400011&lng=pt&nrm=iso&tlng=pt The natural additive products (propolis or essential oils), in replacing antibiotics, could be used as an alternative for feed strategies to improve animal production. This work was performed to evaluate the effect of natural additives as propolis or essential oils on meat quality of crossbred (Aberdeen Angus vs. Nellore) bulls. Thirty bulls were kept in feedlot (individual pen) for 55 d and randomly assigned to one of three diets (n = 10): control (CON), propolis (PRO), or essential oils (OIL). CON diet consists of corn silage (45% DM) and concentrate (cracked corn, soybean meal, glycerin, limestone, and mineral salt, 55% DM). The PRO group received same CON diet plus 3 g animal-1 d-1 of propolis premix added to the concentrate. The OIL group received same CON diet and 3 g animal-1 d-1 of a premix (cashew Anacardium occidentale L. and castor Ricinus communis L. oils) added to the concentrate. Fat thickness (5.0 mm), pH (5.9), Longissimus muscle area 58.0 cm², marbling, texture, color (L* = 36.6, a* = 17.3, and b* = 5.9), lipid oxidation (0.08 malonaldehyde kg-1 meat), and Warner-Bratzler shear force (3.3 kg) were unaffected by the diet. PRO and OIL diets had no effect neither on moisture (73.7%), ashes (1.1%), protein (23.8%), and lipids (1.7%), fatty acid composition or polyunsaturated/saturated fatty acid (PUFA/ SFA, 0.13), and n-6/n-3 ratio (6.9) on Longissimus muscle. Addition of natural additives as propolis extract or cashew and castor oils in the diet of bulls when they are finished in a feedlot did not change meat qualities. <![CDATA[<b>Substitution of peat with municipal solid waste compost in watermelon seedling production combined with fertigation</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400012&lng=pt&nrm=iso&tlng=pt Interest in reusing organic residues as substrate medium in nurseries has increased worldwide as peat availability has been reduced over time. In this study, the effect of fertigation and/or a partial substitution of peat with municipal solid waste compost (MSWC) on the emergence, growth, and nutrition of watermelon (Citrullus lanatus L.) seedlings were tested. The MSWC extracts (MSWC:water at 10-1 and 10-2 dilutions) maintained seedling germination. Under nursery conditions, six media prepared from commercial peat and MSWC were further assessed in conjunction with nutrient application as basic fertilizer (BF) or hydro fertilizer (HF). Adding MSWC to the substrate inhibited seed emergence and mean germination time, whereas fertigation maintained seed emergence in 15% MSWC but decreased in 45% MSWC. Adding 45% MSWC reduced seedling height, leaf number, and fresh weight. The HF increased fresh weight (up to 44%) and growth in seedlings cultivated in 15% MSWC. Leaf photosynthetic rate and stomatal conductance increased (up to 2.6-fold) in MSWC-based (< 45% MSWC) substrates, but no differences were observed in chlorophyll a, chlorophyll b, total carotenoid content, and leaf fluorescence. The HF reduced chlorophyll a and total carotenoids, but increased chlorophyll b content. The K, N, and Na content increased (ranging from 2- to 5-fold) when adding MSWC, whereas P content did not differ. Fertigation benefits seedling nutritive status. Low content (15% to 30%) of MSWC may act as an alternative substitute for peat with more positive effects if minerals are provided through HF. <![CDATA[<b>Influence of soil properties on yield and fruit maturity at harvest of 'Williams' pear</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400013&lng=pt&nrm=iso&tlng=pt In the Upper Rio Negro Valley, northern Patagonia (Argentina), there is a large variability of soils and the success of a fruit plantation depends mostly on soil characteristics. The main objective of this work was to determine the relationships between yield and fruit internal maturity at harvest of pear trees (Pyrus communis L.) grown in soils with different properties. The soil around each of 30 trees was morphologically characterized by measuring physical, physic-chemical, and chemical variables. At harvest time, total and commercial yields were measured, and maturity was determined by measuring flesh firmness, soluble solids, and titratable acidity. According to edaphic variables, soils were classified into five groups. Yields presented significant differences among such groups and growing seasons. The distribution of commercial sizes was similar in soils with fine texture, and high K content (897 and 663 mg kg-1) and cation-exchange capacity. Smaller fruits predominated in soil groups with high salinity (6.1 dS m-1 in surface and 10.8 dS m-1 in subsurface horizons) and shallow depth. The soil group with the highest salinity presented fruits with 11% more titratable acidity compared to all other groups. The soil group with the smallest depth presented fruits with high levels of flesh firmness (11.18 kg cm-2) and soluble solids (14.8%). The selected set of edaphic variables allowed us to differentiate groups of soils and analyze its influence in pear tree yield, commercial sizes, and fruit internal maturity. <![CDATA[<b>Salt-induced root protein profile changes in seedlings of maize inbred lines with differing salt tolerances</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400014&lng=pt&nrm=iso&tlng=pt Salt stress is one of the severest growth limited-factors to agriculture production. To gain in-depth knowledge of salt-stress response mechanisms, the proteomics analysis from two maize (Zea mays L.) inbred lines was carried out using two-dimensional gel electrophoresis (2-DGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). There were 57 salt-regulated proteins identified, 21 and 36 proteins were differentially regulated in inbred lines 'Nongda 1145' (salt-resistant) and 'D340' (salt-sensitive), respectively. The identified proteins were distributed in 11 biological processes and seven molecular functions. Under salt stress, proteins related to antioxidation and lignin synthesis were increased in both inbred lines. The relative abundance of proteins involved in translation initiation, elongation, and protein proteolysis increased in 'Nongda 1145' and decreased in 'D340'. In addition, the abundance of proteins involved in carbohydrate metabolism, protein refolding, ATP synthase and transcription differed between the two inbred lines. Our results suggest that the enhanced ability of salt-tolerant inbred line 'Nongda 1145' to combat salt stress occurs via regulation of transcription factors promoting increased antioxidation and lignin biosynthesis, enhanced energy production, and acceleration of protein translation and protein proteolysis. <![CDATA[<b>Microbial activity of soil cultivated with corn in association with weeds under different fertility management systems</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400015&lng=pt&nrm=iso&tlng=pt Interactions between weeds and soil microorganisms can give them a competitive advantage over crops. This study assessed the biomass and microbial activity of soil cultivated with weeds and corn (Zea mays L.) in monoculture and in competition under different fertility management systems. The experiment considered four soil fertility management systems (calcium and magnesium silicate + fertilization; limestone + fertilization; no correction source + fertilization; no correction source + no fertilization) and 12 crops (five competition arrangements between corn and weeds Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster, lpomoea grandifolia (Dammer) O'Donell, Conyza canadensis (L.) Cronquist, Hyptis suaveolens (L.) Poit., and Bidens pilosa L. plus the six species in monoculture and bare soil. After 60 d coexisting in a greenhouse, soil samples were collected to determine microbial biomass, respiration rate, and metabolic quotient. Soils cultivated with B. pilosa and Z. mays+U. brizantha showed higher microbial biomass. Cultivation of B. pilosa and Z. mays+H. suaveolens provided greater energy efficiency to maintain microbial cells. Biomass and microbial activity were altered by plant species, coexistence, and soil fertility management. Calcium and magnesium silicate, as well as limestone similarly influenced biomass and respiration rate of soil cultivated with most species. For some crops, the Si source was better than limestone to promote lower specific activity of the edaphic microbiota. The change in the microbial activity of soil can be a strategy used by the species to minimize the effects of competition. <![CDATA[<b>Phytoextraction potential of sunflower and white mustard plants in zinc-contaminated soil</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400016&lng=pt&nrm=iso&tlng=pt Phytoextraction relies on plants with a high capacity to absorb heavy metals and remove them from the soil. The objective of this study was to analyze the potential of sunflower (Helianthus annuus L.) and white mustard (Sinapis alba L.) for phytoextraction of Zn-contaminated soil. Research was based on a strict pot experiment conducted in a greenhouse. Seven treatments were established with increasing Zn concentrations: 0, 25, 50, 100, 200, 400, and 600 mg Zn kg-1 air-dry soil. The first tested plant was fodder sunflower. In the following year, white mustard was sown in the same pots. Plants were harvested at the end of the flowering stage. The toxic effect of Zn on sunflower yields occurred at the contamination level of 200 mg Zn kg-1 soil. In the second year of the experiment, a significant decrease in mustard biomass took place in response to 400 mg Zn kg-1 soil. The contamination level of 600 mg Zn kg-1 soil resulted in complete plant death. Plant growth was not inhibited even at high tissue Zn concentrations of 515 mg Zn kg-1 sunflower DM and 422 mg Zn kg-1 mustard DM. The 2-yr cropping system did not contribute to a significant decrease in soil Zn content. Despite high concentrations of Zn in sunflower and mustard plants, total Zn uptake accounted for only 1% to 8% of the Zn rate introduced into the soil. However, in the long run, the growing of crops could reduce Zn contamination levels in the soil. The relatively high tolerance of sunflower and white mustard for Zn contamination and rapid growth of these species are possible alternatives for phytoextraction and phytostabilization of Zn-contaminated soil. <![CDATA[<b>Effect of non-protein factors on heat stability of Chilean Sauvignon Blanc wines</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400017&lng=pt&nrm=iso&tlng=pt Protein denaturation in white wines results into a hazy suspension with precipitate formation, affecting negatively their commercialization. The aim of this study was to identify a number of non-protein factors of wines, which exhibit a modulating effect upon haze formation and interfere with protein precipitation in white wines, applying stepwise multiple regression analysis. The influence of intrinsic non-protein factors, including surface and groundwater quality, on protein haze formation assessed by the heat test was studied. Experiments were performed on 18 Sauvignon Blanc wines from six Chilean valleys. The influence of non-protein factors (pH, electrical conductivity [EC], total and volatile acidity, alcohol, free and total sulfur dioxide, total polyphenols, and chloride, sulfate, K, Na, Ca, Mg, and Fe concentrations) on haze response was evaluated by means of multiple regression analysis. Significant contribution (p < 0.05) of EC, sulfate and Fe concentrations to protein haze was found. Due to multi-collinearity between sulfate and Fe concentrations, the multi-linear model of haze response was reduced to: Haze = -184 + 2.95 x [Protein] - 62.3 x [Fe] + 0.17 x EC (r a = 0.901). Electric conductivities of wine and surface water were correlated (p = 0.037); good correlations were also found between sulfate concentrations in wine and surface water (p = 0.003), and groundwater (p = 0.022). No correlation was detected for Fe. This study elucidates that protein haze formation in white wine is a multi-factorial process. Iron, EC, and sulfate, in addition to protein itself, have to be considered as factors that modulate wine protein hazing. <![CDATA[<b>Effect of 6-benzyl-aminopurine and thidiazuron on <i>in vitro </i>shoot organogenesis of <i>Aloe vera </i>(L.) Burm. f</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400018&lng=pt&nrm=iso&tlng=pt Aloe (Aloe vera [L.] Burm. f.) is an important medicinal herb and is propagated vegetatively. However, its propagation rate is slow and cannot supply good quality planting material to large-scale growers. It is therefore necessary to use in vitro clonal propagation for commercial purposes. The aim of this study was to select a suitable medium for initial culture establishment and subsequent shoot multiplication of aloe. Shoot tips were excised from aloe plants and disinfected with 20% Clorox (5.25% sodium hypochlorite) for 30 min. Sterilized shoot tips were vertically dissected into quarters and then inoculated on Murashige and Skoog (MS) medium supplemented with 6-benzylaminopurine (BAP) or thidiazuron (TDZ) (1, 2, and 3 mg L-1) combined with 0.5 mg L-1 1-naphthaleneacetic acid (NAA). Results revealed that there was a significant difference (P < 0.05) between different hormone combinations in shoot bud formation. Explants placed in 3 mg L-1 BAP and 0.5 mg L-1 NAA produced significantly (P < 0.05) higher numbers of microshoots than other tested treatments. The medium containing a low concentration of TDZ (1 mg L-1) with NAA produced multiple microshoots, whereas the highest TDZ concentration (3 mg L-1) with NAA produced high levels of abnormalities. Transferring microshoot buds from 1 mg L-1 TDZ to 3 mg L-1 BAP accelerated production of prominent and elongated shoots. The MS medium supplemented with 3 mg L-1 BAP and 0.5 mg L-1 NAA produced higher number of normal shoots per explant of aloe under in vitro conditions. <![CDATA[<b>Oviposition of <i>Naupactus cervinus </i>(Boheman) and <i>Naupactus xanthographus </i>(Germar) (Coleoptera: Curculionidae) under laboratory conditions on orange fruit</b>]]> http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-58392014000400019&lng=pt&nrm=iso&tlng=pt Fuller's rose weevil, Naupactus cervinus (= Asynonychus = Pantomorus cervinus) (Boheman), is a cosmopolitan pest that currently represents a serious quarantine problem for the Chilean citrus industry due to its similarity at the egg stage with the quarantine pest Naupactus xanthographus (Germar). The objective of this research was to study the biological aspects associated with N. cervinus and N. xanthographus oviposition habits under laboratory conditions on orange (Citrus sinensis [L.] Osbeck) fruit. Adult N. cervinus and N. xanthographus were collected from the field to carry out the research. Results show that N. cervinus fecundity was higher than N. xanthographus by more than 70%, but egg viability was lower. It was recorded that 71.90% N. cervinus ovipositions were under the calyx. Likewise, 52.46% N. xanthographus ovipositions occurred on leaves and 40.98% on the surface of the plastic cage. In the present study, only N. cervinus lays egg masses under the calyx of citrus fruit.