Scielo RSS <![CDATA[Chilean journal of agricultural research]]> https://scielo.conicyt.cl/rss.php?pid=0718-583920190003&lang=en vol. 79 num. 3 lang. en <![CDATA[SciELO Logo]]> https://scielo.conicyt.cl/img/en/fbpelogp.gif https://scielo.conicyt.cl <![CDATA[Detection and distribution of <em>Ophelimus migdanorum</em> and its possible biocontroller <em>Closterocerus chamaeleon</em> in productive areas of <em>Eucalyptus globulus</em> in Chile]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300337&lng=en&nrm=iso&tlng=en ABSTRACT Wasps that belong to the genus Ophelimus develop galls on Eucalyptus spp., and E. globulus is considered among the most susceptible species. In 2003, a new species of Ophelimus was detected in Chile. This species forms galls on E. globulus and E. camaldulensis, and it was recently considered as Ophelimus migdanorum nov sp. The present study was carried out 16 yr after its detection and it was aimed to determine the presence of Ophelimus in plantations of E. globulus located in Maule, Biobío and La Araucanía Regions, which represent 76% of the area covered with this species in the country. Between August and September 2017, a total of 165 sampling forest farms were established in stands of E. globulus, located in these regions of the country. In each farm, twigs were collected that represented formation of galls and maintained in laboratory conditions until the emergence of adults. These were identified according to their external morphological characteristics. The presence of O. migdanorum and Closterocerus chamaeleon was determined. Both species emerged together in all the regions considered in the study, 92.1% and 46.7% of the evaluated forest farms, respectively. Then Ophelimus migdanorum is widely distributed in Maule, Biobío and La Araucanía Regions, in Chile <![CDATA[Latex quality and yield parameters of <em>Hevea brasiliensis</em> (Willd. ex A. Juss.) Müll. Arg. clone PB 260 for different tapping and stimulant application frequencies]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300347&lng=en&nrm=iso&tlng=en ABSTRACT Tapping and stimulant applications are an attempt to increase latex yield. A combination of stimulants with low intensity tapping systems was expected to reduce tapping costs. In addition, it was necessary to regulate the stimulant application frequency based on type and potential clone production. The objective was to determine the effect on physiological parameters and latex yield of Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. clone PB 260 for different tapping and stimulant application frequencies. The study design was split block in randomized complete block plots with three replicates and two factors. The main plot was the tapping system consisting of four levels: quarter-spiral downward tapping (S/4 d3), quarter-spiral upward tapping (S/4U d3), half-spiral downward tapping (S/2 d3), and half-spiral upward tapping (S/2U d3). The subplots were four stimulant application frequencies consisting of ethephon 2.5% applied once every 15 d (ET 15d) and gas stimulant (equal to ± 100% ethylene) applied once every 9 d (ETG 9d), once every 18 d (ETG 18d), and once every 27 d (ETG 27d). The highest sucrose levels (3.62 mM) were obtained in S/2 d3 and ET/15d combination. The highest inorganic P content (27.68 mM) was in S/2 d3 and ETG/18d. The highest yield (2418.53 kg ha-1 yr-1) was in S/4d3 and ETG/18d. The tapping system S/4d3 and ETG/18d combination was able to increase production by 102.26% compared with the conventional tapping system (S/2 d3 and ET/15d). After the 1-yr trial, all treatments showed 0.47 to 0.54 mM thiol content, which indicated that plants did not experience over-exploitation stress <![CDATA[Community composition of rhizosphere fungi as affected by <em>Funneliformis mosseae</em> in soybean continuous cropping soil during seedling period]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300356&lng=en&nrm=iso&tlng=en ABSTRACT Arbuscular mycorrhizal (AM) fungi can enhance plant resistance particularly against soil-borne pathogenic fungi. However, little is known about the effects of Funneliformis mosseae on the community composition of rhizosphere fungi in soybean (Glycine max [L.] Merr.) continuous cropping soil. Here, the disease index of soybean root rot was analyzed, and high throughput sequencing technology was applied to investigate whether F. mosseae could change the composition of fungal communities in the rhizosphere of continuous cropping soybean during seedling period. The results indicated that the disease index of soybean root rot decreased significantly after inoculation of F. mosseae. The root rot disease index was also affected by the increasing of continuous cropping regimes. Furthermore, the relative abundance of fungal community in soybean rhizosphere soil and root samples was influenced after inoculation. Ascomycota was the dominant phylum in most samples. Basidiomycota was the second dominant phylum in all the soil samples, but Olpidiomycota was the second phylum in most root samples. At the genus level, both inoculation and continuous cropping regimes had significant effects on the dominant genus and their relative abundances in all the samples. The relative abundance of some plant pathogenic fungi such as Fusarium in the inoculated root samples was lower than those in the non-inoculated root samples in the same continuous cropping regime. The results can provide new insights into the interactive effects of AM fungi and rhizosphere fungi, and also provide theoretical evidence on biological solutions to alleviate the obstacles of soybean continuous cropping <![CDATA[Soil carbon dioxide efflux in conilon coffee (<em>Coffea canephora</em> Pierre ex A. Froehner) plantations in different phenological phases in tropical climate in Brazil]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300366&lng=en&nrm=iso&tlng=en ABSTRACT The agricultural sector is considered an important source of greenhouse gases, in which the coffee crop has an important contribution, participating in the dynamics of soil C and CO2 emissions. In this way, the aim of this study was to analyze and quantify CO2 emissions in different phenological phases in soil cultivated with conilon coffee (Coffea canephora Pierre ex A. Froehner), and compare it with CO2 flow in forest and pasture area. The experiment was conducted in the Experimental Area of the Federal Institute of Espírito Santo, Southeastern Brazil, in an experimental plot of 0.5 ha cultivated with conilon Vitória coffee clones. The quantification of soil CO2 flux was performed between July 2016 and June 2017, this period comprising all the seasons of the year, using in two rounds of ratings (day and night), with five replicates each. For comparison purposes, another measurement of the CO2 stream was conducted in June 2017 with an evaluation period of 24 h. The highest CO2 emission occurred during the harvest phases of the fruit (206.7 mg CO2 m-2 h-1). The lowest daily CO2 flow records were observed in the rest and flowering phases with values of 82.1 and 83.6 CO2 mg m-2 h-1, respectively. The CO2 emission from the forest was higher than the emissions that occurred in the area planted with conilon coffee and pasture, during dry season <![CDATA[PCR diagnosis and <em>in vitro</em> sanitation of the papaya MSXJ hybrid with ringspot virus disease]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300376&lng=en&nrm=iso&tlng=en ABSTRACT Papaya (Carica papaya L.) is a tropical fruit with a high nutritional value. Current problems affecting its cultivation are the limited number of exploited varieties and its susceptibility to pests and diseases. The papaya MSXJ hybrid is resistant to pests and diseases, and its organoleptic characteristics are prominent compared with most papaya genotypes on the market. Samples of Papaya ringspot virus (PRSV) disease were evaluated by in vitro culture of the apical meristems and thermotherapy. Sanitation of apical meristems was accomplished by regenerating them with or without light and thermotherapy was performed at 40 and 45 °C for 4 and 7 h, respectively. Both situations were observed for 45 d to evaluate survival, regeneration, and sanitation by reverse transcription polymerase chain reaction (RT-PCR). In vitro culture of the meristems in total darkness obtained the highest survival rate (87%) and regeneration (22%) compared with the treatments under photoperiod (21% and 18%, respectively). Under both study conditions, sanitation in PRSV was 100% of the meristems. Plants subjected to thermotherapy showed a higher survival rate (99.92%) at 40 °C for 4 h and sanitation of 80.2% <![CDATA[Study of physiological and quality parameters during development and ripening of pepino (<em>Solanum muricatum</em> Aiton) fruit]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300385&lng=en&nrm=iso&tlng=en ABSTRACT Pepino (Solanum muricatum Aiton) fruit served as an important crop in Pre-Columbian Andean cultures. Despite the fact that pepino has been known for centuries, information about maturity indices and physiological quality parameters of its fruit is scarce. The objective was to increase our knowledge of pepino fruit physiology and maturity to improve fruit handling and storage. Pepino fruit were studied during 2015 and 2016 seasons. During 2015, developmental and maturity studies were carried out, whereas in 2016 the developmental study was repeated. Twenty-five fruit were analyzed during six developmental stages ranging from immature (stage 1) to senescent fruit (stage 6). Fruit were analyzed for soluble solid content (SSC), titratable acidity (TA), color, respiration and ethylene production, soluble sugars, organic acids, and aroma. For the maturity assay, nonsignificant differences were found between green background color (M1) and white background color (M2) in the different quality parameters, with the exception of firmness. Pepino is a non-climacteric fruit with a low ethylene production rate. Unlike foreign cultivars, Chilean pepinos have low amounts of citric acid, being the predominant acids: malic and quinic. Out of 22 volatile compounds identified in this study, the predominant aroma volatiles are 3-methyl-3-butenyl acetate and 3-methyl-2-butenyl acetate from the terpenoid pathway, and trans-2-hexenal from the lipoxygenase pathway. The quality parameters changing in a ripening-dependent manner were firmness, SSC, aroma and color. Other parameters such as TA and organic acids stayed constant throughout development. In addition to color and SSC, this study also suggests aroma as a harvest index <![CDATA[Seed soaking with <em>Bacillus</em> sp. strain HX-2 alleviates negative effects of drought stress on maize seedlings]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300396&lng=en&nrm=iso&tlng=en ABSTRACT Drought, one of the most detrimental environmental factors for agricultural production all over the world, severely represses plant survival and productivity of crops. Microbial technology plays a prominent part in improving drought resistance of crops. Here, endophytic bacterium Bacillus megaterium strain HX-2 was isolated from healthy leaves of Agastache rugosa (Fisch. &amp; C.A. Mey.) Kuntze; its drought tolerance level and growth promoting characteristics were carried out in vivo, and the effects of the bacterium on morphological, physiological and biochemical variables of maize (Zea mays L.) seedling under drought stress were investigated in a pot experiment. As a result, B. megaterium strain HX-2 had 15% tolerance to polyethylene glycol 6000, produced indoleacetic acid and dissolved phosphate. After inoculation with strain HX-2, plant height, root length, plant biomass, root:shoot ratio, root activity, leaf relative water content, proline content, plant P content, and enzyme activities including superoxide dismutase, catalase, peroxidase and ascorbate peroxidase increased considerably by 7.69%-42.9%, whereas electrolyte leakage and malondialdehyde content declined significantly by 28.17%-42.38% relative to drought stress. These changes suggested that strain HX-2 was able to alleviate negative effects of drought stress on plants by producing indoleacetic acid and dissolving phosphate to improve the antioxidant system of plants. This study will provide theoretical reference for cultivation of maize under drought stress <![CDATA[Critical period of weed interference on total polyphenol content in quinoa]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300405&lng=en&nrm=iso&tlng=en ABSTRACT There is limited information about the critical period of weed interference (CPWI) in quinoa (Chenopodium quinoa Willd.) and the effect produced by the weed-crop interaction in secondary metabolite accumulation. The objective of the present study was to determine the CPWI and its effect on total polyphenol content in quinoa. The experiments were conducted during two consecutive seasons using a randomized complete block design with 16 treatments consisting of 8 weed growth periods and 8 weed-free growth periods in which weed population and biomass were evaluated; productive parameters, yield components, and total polyphenols were determined in the quinoa crop. Grain number per plant affected yield because of weed interference (P &lt; 0.05), which decreased from 4312 to 162 grains plant-1 in weed growth periods and increased from 181 to 5110 grains plant-1 in weed-free growth periods. Total polyphenol content was affected by stress from weed interference (P &lt; 0.05), which increased from 2.2 gallic acid equivalents (GAE) g-1 to 3.6 mg GAE g-1 in weed growth periods and decreased from 3.6 GAE g-1 to 1.9 mg GAE g-1 in weed-free growth periods, while the population remained constant (P &gt; 0.05). The CPWI was determined between the phenological stages of two true leaves to flowering; therefore, the quinoa crop must remain weed-free between these two phenological stages to rule out production losses greater than 5% <![CDATA[Effects of gibberellic acid on water uptake and germination of sweet sorghum seeds under salinity stress]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300415&lng=en&nrm=iso&tlng=en ABSTRACT Sweet sorghum (Sorghum bicolor [L.] Moench) is a potential feedstock crop in biomass energy development, and is much more resistant to saline soils than crops. Healthy seed germination is critical for the growth cycle of plants, and determines the establishment of seedlings and subsequent crop production. High salinity conditions can result in difficulty for seed germination and delays the germination period. So, screening salt-tolerant genotypes and method for healthy seed germination under salinity stress are vital to crop production and food security. Therefore, a controlled study was conducted to explore the interactive amendment effects of exogenous gibberellic acid (GA3) and salinity on seed germination process of sweet sorghum. Seeds were presoaked in different levels of GA3 water solutions (0, 144, 288, and 576 μM) and then cultivated in gradient NaCl solutions (0, 50 and 100 mM). The effects of salinity and external GA3 on seed water uptake and germination characteristics were investigated. Compared with the effects of 0 μM GA3 at 0 mM NaCl, slight salt stress of 50 mM NaCl improved the cumulative water uptake, germination and germination index, but high salinity level of 100 mM NaCl significantly inhibited these germination traits. However, either 100 mM NaCl or 576 μM GA3 had significantly negative effects on seed cumulative water uptake, cumulative germination, germination index, and length of germ and radicle. The appropriate concentration of GA3 prominently relieved salt stress and improved the seed germination of sorghum seeds, and the optimum concentration for seed germination of sweet sorghum was 288 μM GA3 at each salinity level <![CDATA[Silicon mitigates ammonium toxicity in yellow passionfruit seedlings]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300425&lng=en&nrm=iso&tlng=en ABSTRACT Ammonium (NH4 +) toxicity in yellow passionfruit (Passiflora edulis Sims f. flavicarpa O. Deg.) may be mitigated by Si application. This study aimed to evaluate the interaction effect of Si and high level of NH4 + on yellow passionfruit seedlings nutrition, physiology, growth, and DM production. Pots were filled with pinus bark and nutrition solution was applied. Treatments were arranged in a completely randomized design, with five replicates, in a 2 × 2 factorial scheme: two ratios of NH4 + and nitrate, NO3 + (40/60%, without high level of NH4 +; and 75/25%, with high level of NH4 +) at N concentration of 13 mmol N L-1, in the absence and presence of Si (2.0 mmol L-1). Sixty days after seedling transplant it was evaluated: N, Si, K, Ca and Mg root and shoots accumulation, leaf green color index (GCI), electrolyte leakage index (ELI), intracellular CO2 concentration (Ci), transpiration rate (Tr), stomatal conductance (gs), net photosynthesis rate (Pn), stem diameter, leaf area, root length, N use efficiency (NUE) and root and shoot DM content. Plants cultivated with Si had 19.1% and 16.3% lower Tr and gs, respectively, regardless NH4 + concentration. Moreover, Ci and Pn were 13.2% and 16.4%, respectively, higher in plants that received Si. Plants cultivated under high NH4 + concentrations, with Si application had 17% bigger stem diameter and 15.4% bigger root length than plants without Si application. Si application in yellow passionfruit seedlings cultivated with high level of NH4 + increased accumulation and NUE, root length, root DM, and GCI. In addition, Si application reduced ELI, which resulted in higher stem diameter. These results prove that Si application mitigates NH4 + toxicity in yellow passionfruit seedlings <![CDATA[Co-application of soil superabsorbent polymer and foliar fulvic acid to increase tolerance to water deficit maize: photosynthesis, water parameters, and proline]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300435&lng=en&nrm=iso&tlng=en ABSTRACT Fulvic acid (FA) and superabsorbent polymer (SAP) are widely applied to improve crop growth and yield under water deficit conditions, but little is known about the changes in crop physiological parameters related to water deficit tolerance when SAP and FA are combined. A pot test with maize (Zea mays L.) plants was conducted to examine the combined effect on photosynthesis, leaf water, proline, and growth under soil water deficit. Maize plants were subjected to two soil moisture conditions at the late crop growth phase: water deficit (WD, 50% field capacity) and well-watered (WW, 80% field capacity). The SAP (4.5 g m-2) was mixed into the soil layer at sowing and the FA solution (2 g L-1) was sprayed twice during water control. The combined application significantly improved maize grain yield under both watering conditions. The net photosynthesis rate, intrinsic quantum yield, fluorescent parameter (Fv/Fm), and chlorophyll content all improved with the combined application under both watering regimes. The compensating effect of combining chemicals on yield and photosynthesis parameters was higher than when applied alone under the two watering conditions. For prolonged and WD conditions, leaf proline and water content were higher under the combined treatment than when used separately. Under the WD conditions treated with FA and SAP, Fv/Fm had positive significant correlations with leaf water content and osmotic potential; leaf proline did not show any correlations with either the osmotic potential or leaf water content. This result demonstrated that SAP and FA could be combined to maintain high leaf proline and improve photosynthesis to mitigate adverse effects of moderate water storage on maize growth <![CDATA[Nitrogen use efficiency and forage production in intraspecific hybrids of <em>Paspalum notatum</em> Flüggé]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300447&lng=en&nrm=iso&tlng=en ABSTRACT The rational use of N fertilization is essential to increase the recovery efficiency and crop productivity and decrease the cost of production. The objective of this study was to assess forage yield (TDM), tillers population density (TPD) and N use efficiency (NUE) in six Paspalum notatum Flüggé genotypes in response to N fertilization. The experimental design involved randomized blocks on a subdivided plot design. In 2014-2015 the TDM was higher for the C22 and B26 hybrids (P &lt; 0.0001), which were similar to each other, with an average of 6173 kg DM ha-1 yr-1. In 2015-2016 the TDM of the genotypes ranging from 7053 to 13773 kg DM ha-1 yr-1, for pastures fertilized with 0 and 480 kg N ha-1 yr-1, respectively. An interaction was found between Genotype × N fertilization level (P = 0.0155) for TDM in 2016-2017. In the years 2015-2016 and 2016-2017 the C22 hybrid standed out as the genotype with the highest tiller production in response to N fertilization. In the year 2014-2015 NUE was higher (P = 0.0015) in the N fertilization levels N60, being of 15.5 kg DM kg-1 N. In the years 2015-2016 and 2016-2017 the NUE was higher at fertilization level N120 (P &lt; 0.05), being of 21.1 and 31.5 kg DM kg-1 N, respectively. The C22 hybrid was distinct as the genotype with the highest DM yield and superior tillering characteristics. The N fertilization level of 120 kg N ha-1 yr-1 promoted greater NUE in all P. notatum genotypes <![CDATA[Selection of common bean lines obtained by the genealogical and bulk methods for disease resistance and agronomic traits]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300456&lng=en&nrm=iso&tlng=en ABSTRACT A common bean (Phaseolus vulgaris L.) breeding program aims to obtain high yielding lines with quality bean seeds, disease resistance, and upright plant growth habit. The aims of this study were to evaluate the resistance of 527 common bean lines to the principal physiological races of Colletotrichum lindemuthianum and the Fusarium oxysporum f. phaseoli; to estimate genetic parameters and verify the efficiency of the genealogical and bulk methods in conducting these lines. Of these 527 lines, 279 were conducted by the genealogical method and 248 by the bulk method. For the field experiment, the Federer augmented block experimental design was used. Two commercial cultivars carioca seed coat were used as controls for the lines the same color, and more two commercial cultivars for the black seed coat lines. The traits evaluated in the field were plant height (PH), plant growth habit (P), bean seed yield (BY), sieve yield (SY), and lightness of the bean seed coat (L). Of the 527 lines evaluated for anthracnose, 207 were resistant, 57 moderately resistant, and 263 susceptible. For fusarium wilt, 58 were resistant, 53 moderately resistant, and 96 susceptible. For the carioca seed coat lines obtained by the genealogical method, the heritability (h²) estimates stood out for P, BY, L at 40 d, and gain from selection for BY. The h² stood out for black seed coat lines in the PH and SY traits, it can be concluded that the lines obtained by the genealogical method had better performance for all the traits <![CDATA[Milk fatty acid profile of dairy cows fed diets based on sugarcane bagasse in the Brazilian region]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300464&lng=en&nrm=iso&tlng=en ABSTRACT Little is known about milk fatty acid (FA) profile of cows fed diets based on sugarcane (Saccharum officinarum L.) bagasse. This study aimed to evaluate FA profile and nutritional quality indexes of milk fat of cows fed sugarcane bagasse and concentrate in the Brazilian northeast semiarid region. Multiparous Girolando cows were allocated in four diets based on different levels of sugarcane bagasse (30%, 38%, 46%, and 54% total DM) added to concentrate. Fatty acids C18:1 trans-11 (lowest value for 46% inclusion) and conjugated linoleic acid (CLA) cis-9, trans-11 (lowest value for 46% inclusion) in milk fat presented a quadratic pattern (P &lt; 0.05). This trend was also observed for C18:1 cis-9 (P &lt; 0.05), but at a lower magnitude. There was a reduction in concentration of C18:1 trans-10 (0.320 to 0.148 g 100 g-1 total FA) and CLA trans-10, cis-12 (0.008 to 0.004 g 100 g-1 total FA) according to the levels of sugarcane bagasse increase. The greater inclusion of bagasse and consequent reduction in the proportion of concentrate, notably corn, cause an increase in concentration of medium-chain saturated FA and a linear reduction of C18:3 n-3 and C18:2 n-6, with a consequent increase in the indexes of atherogenicity (2.82 to 3.2) and thrombogenicity (3.39 to 3.84) and a decrease in ratio of hypo/ hyper-cholesterolemic (0.44 to 0.37) and ω-6:ω-3 (12.44 to 8.80) in milk fat. Results indicate that different levels of sugarcane bagasse change the FA content in cows’ milk when bagasse is an exclusive roughage source in the diet. The greater inclusion of sugarcane bagasse reduces the quality of milk fat of dairy cows. The lowest level of sugarcane bagasse inclusion tested (30%) promotes greater milk yield and healthier milk fat <![CDATA[Plant growth-promoting rhizobacteria able to improve NPK availability: selection, identification and effects on tomato growth]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300473&lng=en&nrm=iso&tlng=en ABSTRACT Nitrogen, P and K are essential macronutrients that are not readily available to plants. Rhizobacteria are able to convert these unavailable forms for subsequent uptake by the plant, diverse species have been characterized as N2 fixers, P solubilizers and capable to solubilize mineral K from unavailable forms. The objective of this study was to select rhizobacteria capable of improving NPK availability and promoting tomato (Solanum lycopersicum L.) growth. Fifteen strains were studied. Four strains were selected for their capacity to fix N2, three for their ability to solubilize P, and six for their capacity to solubilize biotite and K-feldspar, isolated from tomato, lentil, chili pepper, faba bean and lettuce crops in Andisol and Alfisol soils. Through 16SrRNA sequencing, selected strains were identified as Pseudomonas gessardi, P. koreensis, P. brassicacearum, P. marginalis, Acinetobacter calcoaceticus and Rahnella aquatica. Phosphorus solubilizing strains did not show a positive effect on plant growth or an increase in available soil P. The N2 fixing bacteria Tmt-16 strain increased root growth in 23.57%; maintained the highest N content in plant tissue, 2.60%, higher amount of N available in the soil, 2.95 mg kg-1, and a higher content of N-NH4 + 1.95 mg kg-1. The K solubilizing strains Ls-C21, Ltj-62 and LsC-58 reached 17.0 to 19.0 mg kg-1 available K and 0.04 to 0.05 mg kg-1 exchangeable K (p ≤ 0.05.). These four endemic rhizobacteria can be potentially used as biofertilizers, allowing a reduction in the use of chemical fertilizers and a more sustainable production of tomatoes <![CDATA[Sulphur nutrition index in relation to nitrogen uptake and quality of winter wheat grain]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300486&lng=en&nrm=iso&tlng=en ABSTRACT A sulphur nutrition index (SNI) is an analogue of the N nutrition index, which is a widely used simple indicator of plant N status. The aim of this study was to relate the SNI (ratio of S concentration in shoot biomass to critical S concentration - Sc) to N uptake, grain yield and breadmaking quality of winter wheat (Triticum aestivum L.) grain during 4-yr small-plot field experiments realized under non-limiting N conditions in three different locations in the Czech Republic. The model of S dilution curve (Sc) developed by Reussi et al. (2012) for spring wheat was used for expression of the SNI. According to the model, optimal S concentration in shoot biomass was calculated using nothing but shoot biomass weight. The constant value of Sc = 0.55 was determined for shoot biomass weight lower than 1.0 t ha-1. A very strong correlation was recorded between the SNI and an N to S weight ratio (N:S) in shoot biomass. Both, optimal N:S weight ratio in shoot biomass and qualitative parameters of grain (particularly Zeleny sedimentation volume, grain protein content and wet gluten content) were recorded if the SNI exceeded values of 0.80 at the beginning of stem elongation, 0.70 at the late boot stage, and even 0.60 at the beginning of heading despite the fact that the Reussi et al.’s model of S dilution curve was originally applicable only until the end of stem elongation. Correlation between the SNI and relative grain yield was weak <![CDATA[Identification of a phytoplasma associated with witches’ broom symptoms in calafate (<em>Berberis microphylla</em> G. Forst.)]]> https://scielo.conicyt.cl/scielo.php?script=sci_arttext&pid=S0718-58392019000300493&lng=en&nrm=iso&tlng=en ABSTRACT Berberis microphylla G. Forst. (“calafate”) is a native berry grown in the Patagonian area of Chile and Argentina. The calafate fruit have important commercial projection, given that contains antioxidant characteristics with high levels of phenolic compounds and anthocyanins. Recently, wild growth of calafate present in Region of Magallanes y la Antártica Chilena has been affected by symptoms of witch’s broom, which is associated to infections caused by phytoplasmas. To determine the presence of phytoplasmas in calafate plants affected by these symptoms, symptomatic and asymptomatic samples were analyzed. To identify the phytopathogen, nested polymerase chain reaction (nested-PCR) was used with three pairs of primers (P1/P7, R16mF2/mR1, R16F2n/R2); sequencing of the fragments obtained from PCR and an in silico restriction analysis was carried out on the obtained genomic sequences. Results from nested-PCR showed an expected band of 1.2 kb only in the samples with symptoms. The nucleotide sequence obtained from the amplified DNA fragment had similarity to 99% of other phytoplasmas present in the National Center for Biotechnology Information (NCBI) database, according to a basic local alignment search tool (BLAST) analysis. Restriction analysis indicated that the amplified DNA fragment corresponded to a phytoplasma from the 16SrXIII-f group. In conclusion, the symptoms of witch’s broom present in the analyzed calafate plants from Magallanes region signal the presence of the phytoplasma “Candidatus Phytoplasma hispanicum” pertaining to the group 16SrXIII-F