Scielo RSS <![CDATA[Chilean journal of agricultural research]]> vol. 74 num. 3 lang. pt <![CDATA[SciELO Logo]]> <![CDATA[<b>Response of root characteristics and yield in peanut under terminal drought condition</b>]]> Drought at pod filling reduces growth, yield, and seed quality of peanut (Arachis hypogaea L.) Great root system can reduce yield loss under water stress. There is a lack of information on root traits for peanut genotypes and the relationship between rooting traits and peanut yield under terminal drought. The pot experiments were conducted at Khon Kaen University, Thailand, in 2004-2005 and 2005-2006. A randomized complete block design was used with two factorials set-up with four replicates. Factor A consisted of two water regimes (field capacity and 1/3 available water at 80 d after planting to harvest), and factor B comprised of 11 peanut genotypes. Data were recorded for root traits (root dry weight, root length, root surface, root diameter, and root volume), and peanut yield (pod dry weight, biomass, and harvest index) were measured at final harvest. Terminal drought significantly decrease root characteristics (0.83-1.03 g plant-1 of root dry weight) and peanut yield (7.98-8.89 g plant-1 of pod dry weight). Yield responses to terminal drought were not correlated with root traits except root length and root volume (r = 0.71** and 0.83**, respectively). Some genotype, root traits seem to be correlated with peanut yield under terminal drought. 'KK60-3' showed high root traits, maintained pod dry weight under terminal drought, whereas Tifton 8 maintained biomass production. ICGV98348 had high root traits, maintained pod dry weight and harvest index under drought conditions. The results suggested that peanut contained high root characters which maintained yield under terminal drought. <![CDATA[<b>Physiologic characteristics of corn and <i>Urochloa brizantha </i>(Hochst. ex A. Rich.) R.D. Webster in intercropping cultivation</b>]]> Competition between weeds and crops results in a lower availability of some resources to crop species, which causes deficiencies, such as water and nutritional deficiencies and low light quality or quantity. The aims of this study were to evaluate the effects of Urochloa brizantha (Hochst. ex A. Rich.) R.D. Webster, cv. Xaraes (brachiaria) emergence times comparing with corn (Zea mays L.), in addition to the fertilization and application of different nicosulfuron and atrazine herbicides levels, on the physiological characteristics of intercropped species. The physiological characteristics Brachiaria plants that were treated with herbicides were negatively affected. The emergence time of Brachiaria plants in comparison with corn altered the physiological characteristics of both. The Brachiaria plants that emerged before corn presented higher photosynthetic and transpiration rates and reduced the intensity of these characteristics in corn. Thus, the Brachiaria plants that emerged before the corn crop presented a higher physiological efficiency, and they were more competitive than the weeds that emerged during other seasons. <![CDATA[<b>Agronomic performances of three vetch species growing under different drought levels</b>]]> The current challenge of agriculture is to get the best yields while overcoming frequent water deficit conditions. The objective of this study was to compare performances of three vetch species (Vicia narbonensis L., V. sativa L., and V. villosa Roth) subjected to water stress. Plants were sown in pots under rainout shelter and submitted to four water regimes: control (100% field capacity [FC]), 80%, 60%, and 40% FC through 3 yr experiment. Results showed that V. narbonensis had the smallest declines in all the studied variables in response to water restriction but the highest water use efficiency (WUE) and stress tolerance index (STI) in both control and water-treated plants. This indicates the greater tolerance of this species to water constraint and its better water use. Vicia villosa was characterized by drastic declines in leaf area and DM yield (75% and 64%, respectively). It had also the smallest WUE and STI suggesting its low adaptation to water stress. Vicia sativa showed severe reductions in seed yield and yield components; accordingly, it was the most sensitive species in terms of seed yield. The three species implied avoidance strategies to cope with water stress. The different levels of drought tolerance explain the species ecological distribution in Tunisia. <![CDATA[<b>Essential oils as biological alternatives to protect date palm <i>(Phoenix dactylifera </i>L.) against <i>Ectomyelois ceratoniae </i>Zeller (Lepidoptera: Pyralidae)</b>]]> The aims of this research were to determine the chemical composition of the essential oil of three Tunisian plants and to evaluate their biological activity against eggs, larvae, and adult insects of Ectomyelois ceratoniae Zeller. The essential oils extracted from leaves of Thymus capitatus (L.) Hoffmanns. & Link, Rosmarinus officinalis L. and needles of Pinus halepensis Mill. were analyzed by gas chromatography-mass spectrometry; 34, 16, and 56 constituents were identified, respectively. The major constituents were (Z)-caryophyllene (23.8%), β-myrcene (20.5%) and α-pinene (13.3%) in P. halepensis oil, carvacrol (66.9%), p-cymene (9.1%), and δ-terpinene (6.2%) in T. capitatus oil and 1,8-cineole (47.5%), camphor (14.9%), α-pinene (14.1%), and borneol (13.1%) in R. officinalis oil. The insecticidal effects of essential oils on eggs, larvae, and adults of E. ceratoniae were investigated. Ovicidal activity of oils was studied by spray on eggs while larvicidal and adulticidal activities were assessed by fumigation and spray. Number of hatched eggs was verified after 10 d, larva and adult mortalities were observed after 6, 12, and 24 h. Globally, eggs and larvae were the most resistant to the three different oils, needing higher doses to obtain a higher mortality. The spray method was most effective than fumigation. Essential oil extracted from T. capitatus proved to be very toxic towards E. ceratoniae on all three phases at the dose of 20 μL mL-1 (100% inhibition), followed by the oil from R. officinalis (90-100% inhibition), nevertheless, weak activity was obtained with P. halepensis oil (68.3-85% inhibition). Results obtained may suggest that the essential oils of T. capitatus and R. officinalis possess high insecticidal activity and therefore, can be used in biotechnological application as natural preservative in stored dates and could be useful in managing populations of E. ceratoniae in field. <![CDATA[<b>Ruminal pH and temperature, papilla characteristics, and animal performance of fattening calves fed concentrate or maize silage-based diets</b>]]> Feeding systems can play an important role, not only in beef farm profitability but also in animal health and performance. Fourteen Avilena-Negra Iberica bulls, with an initial weight of 270 kg (SE 22.6 kg) and aged 223 d (SE 16.2) were used to study the effect of two feeding systems on ruminal pH and temperature and animal performance when calves were kept in loose housing conditions. Feeding systems were barley (Hordeum vulgare L.) grain-based concentrate plus barley straw (CONC) and maize (Zea mays L.) silage-based total mixed ration (TMR). Internal wireless boluses were used to collect pH and temperature values every 10 min throughout the measurement period (15 d). Diet did not modify (P &gt; 0.10) average daily gain, carcass weight, dressing percentage, ruminal mucosa color, or papilla counts. Papilla width and papilla width/lamina propria thickness were significantly lower (P < 0.05) in TMR than in CONC animals. Time spent below ruminal pH thresholds of 7.0, 6.6, 6.2, and 5.8 and the corresponding areas under the curve were higher (P < 0.05) for animals fed under the TMR system. No significant changes were observed between experimental treatments in parameters related to ruminal temperature or estimated number of times that the animals were drinking during the day (P &gt; 0.10). Although animal performance is not affected, feeding fattening calves on a concentrate plus barley straw diet can result in better rumen conditions than using maize silage-based TMR. <![CDATA[<b>Ingestive behavior of grazing heifers receiving crude glycerin supplementation during the dry-rainy season transition</b>]]> The search to find food alternatives for corn and feeding alternatives that reduce the cost of production has been constant. The use of oleaginous grains to produce ethanol and biodiesel has produced an excess of byproducts, especially biodiesel which produces crude glycerin. The objective of this study was to evaluate the effect of including crude glycerin on the ingestive behavior of crossbred heifers supplemented with pasture. Thirty-six crossbred heifers with an initial mean weight of 301.5 ± 31 kg were distributed in a completely randomized design with four treatments and nine replicates per treatment. The animals were kept in a Brachiaria brizantha (Hochst. ex A. Rich.) Stapf 'Marandu' pasture in a rotational-grazing system. The treatments tested were 0.0%, 3.33%, 6.66%, and 9.99% crude glycerin included in total DM to replace corn (Tea mays L.) Including crude glycerin reduced the time for grazing and eating at the trough and increased idle time. Rumination was quadratically influenced. Eating time (min kg-1 DM and neutral detergent fiber [NDF]) was reduced, while rumination time (min kg-1 DM and NDF) was quadratically affected by adding glycerin. The variables, time spent per ruminated bolus and the number of chews per day, were not affected. The number of boluses per day showed a quadratic effect. The number of grazing, idle, ruminating, and eating at the trough periods were not affected by including crude glycerin; means were 15.1, 24.9, and 13.3 and 3.71 periods d-1, respectively. Feed and rumination efficiency (kg h-1 DM and NDF) increased when crude glycerin was included in the diet. Including crude glycerin promotes feed and rumination efficiency in grazing heifers. <![CDATA[<b>Dehydrated olive-waste cake as a source of high value-added bioproduct</b>: <b>Drying kinetics, physicochemical properties, and bioactive compounds</b>]]> Olive (Olea europaea L.) oil processing produces significant amount of waste that can be utilized for the production of high value-added ingredients for various industrial applications. In this work, the effects of temperature on drying kinetics and quality indexes of the olive-waste cake during convective dehydration (40-90 °C) were investigated. Results on effective moisture diffusivity, physicochemical parameters, fatty acid profile, total phenolic, flavonoid, and flavanol contents as well as antioxidant capacity are also reported. Most of the fatty acids increased their content with respect to control sample with a temperature increase, i.e. oleic and linoleic acids increased 48% and 43% at 70 and 40 °C, respectively. Total flavanol content increased with temperature (48-62 mg catechin equivalents [CTE] 100 g-1 DM) except for 80 °C. Total phenolic and total flavonoid contents were highly correlated to antioxidant capacity (0.923 < r < 0.992), except for 70 and 80 °C, the rest of the samples maintained their initial antioxidant capacity by ORAC analysis. Thus, these parameters show that dried olive-waste cake has a high bioactive compounds with potential use as additives for the food or other industries. <![CDATA[<b>Evaluation of water use and yield responses of drip-irrigated sugar beet with different irrigation techniques</b>]]> Effective water use should be investigated in terms of sustainable production strategy in arid and semi-arid regions. A 2 yr field study was conducted in order to investigate the effects of full root-zone wetting (FI) and partial root-zone drying (PRD) irrigation techniques with 4 and 8-d (I2) irrigation intervals and three different irrigation levels (W1, W2, W3) adjusted according to Class A pan evaporation on root, leaf, and sugar yields and irrigation water use efficiency (IWUE) of sugar beet (Beta vulgaris L.) Three different plant-pan coefficients (0.70, 0.60, and 0.50) were used for adjusting the three different irrigation levels. The irrigation techniques and levels affected yields significantly. Seasonal meanly irrigation quantities were 280.4 mm in FI treatments and 162.4 mm in PRD treatments. While mean root yield of 33.80 t ha-1 is obtained in FI treatments, it was 26.43 t ha-1 in PRD treatments. Similarly, mean white sugar yield (WSY) for FI treatments (5 t ha-1) was higher than PRD treatments (3.81 t ha-1). There were significant polynomial relationships between irrigation quantities and root yield or WSY in both FI and PRD treatment. PRD technique increased by 34.9% IWUE compared to FI. Although the highest root yield was determined in FI-I1W1 sub treatment as 37.57 t ha-1, the highest IWUE was determined in PRD-I1W3 sub treatment as 173.9 kg ha-1 mm-1 since it has the lowest irrigation water amount as 140.6 mm. However, among PRD treatments for more root yield and for more white sugar yield, I1W1 and I1W2 sub treatments were the best. <![CDATA[<b>Swine manure application methods effects on ammonia volatilization, forage quality, and yield in the Pre-Amazon Region of Brazil</b>]]> The use of swine manure (SM) as a nutrient source for pastures is increasingly common in Brazil, due to its low cost. However, this practice can cause N losses in agricultural soil, where ammonia (NH3) volatilization may be the main drawback, generating undesirable economic and environmental consequences. The objective of this study was to evaluate SM application methods that retain N within the system and determine how these methods affect forage yield and quality. The study was conducted in the municipality of Chapadinha, Maranhão, Brazil, and the following SM application methods were evaluated: (1) surface application, (2) incorporation at 5-cm soil depth, (3) incorporation at 10-cm soil depth, and (4) control when SM was not applied. Lower N losses due to NH3 volatilization and higher pasture yield and quality were found when SM was incorporated at 10-cm soil depth (83 kg N-NH3 ha-1 and 6.3 Mg DM ha-1, respectively, compared to 86 kg N-NH3 ha-1 and 1.5 Mg DM ha-1 for the control), whereas higher N-NH3 losses and lower pasture yield were observed when SM was applied to the soil surface (143 kg N-NH3 ha-1 and 2.6 Mg ha-1, respectively). Higher quality forage in terms of chemical composition was also observed when SM was incorporated at greater soil depth. Incorporating SM at 10-cm depth represents an efficient management to mitigate N-NH3 volatilization, and this application method is associated with significantly increased in DM yield and improved chemical composition. <![CDATA[<b>Isolation and selection of fluorescent pseudomonads based on multiple plant growth promotion traits and siderotyping</b>]]> Fluorescent pseudomonads, acclaimed plant associated bacterial group, are well-known plant growth promoting-biocontrol agents in rhizosphere arena. In this study, 144 fluorescent pseudomonad isolates from rhizosphere soil samples were screened with King's medium B supplemented with 8-hydroxyquinoline (8-HQ) chelator and comprehensively profiled for plant growth promotion viz., production of indole acetic acid (IAA), siderophore, ammonia, hydrogen cyanide, motility, phosphate solubilization, root growth promotion, and biofilm forming ability, along with two known control strains of pseudomonads. Iron and IAA regulated secondary metabolite siderophore production were investigated quantitatively. All isolates were positive for ammonia production and motility; 46% isolates were positive for hydrogen cyanide, 44% shown positivity for phosphate solubilization, and 40% isolates for siderophore production. Siderotyping showed production of hydroxamate type of siderophores which are known to be more efficient biocontrol agents. All isolates stimulated root growth to varying extent and had potentiality to form biofilms, a critical constituent for survival on different environments. Forty-two isolates of pseudomonads showed antagonistic behavior against the deleterious fungal pathogen Fusarium oxysporum (MTCC1755). Based on the above observations and statistical analysis, 11 isolates were shortlisted for further scrutiny. The study of biogeographic correlation and secondary metabolite profiling in association with plant growth promotion focalizes significant assessment on the behavior and antagonistic action, which probably brings out a competent biocontrol agent in a sustainable eco-friendly dimension. <![CDATA[<b>Differences in maize physiological characteristics, nitrogen accumulation, and yield under different cropping patterns and nitrogen levels</b>]]> Intercropping and N fertilization play an important role in increasing crop yield. In order to further understand the advantage mechanism of intercropping and the effect of increasing N application on the advantage effect of intercropped crop, a field experiment was conducted to investigate the effects of different cropping patterns (i.e. M, maize monoculture; I1, maize-cotton intercrop; I2, maize-soybean intercrop) and N fertilization levels (N1, 100 kg ha-1; N2, 200 kg ha-1; N3, 300 kg ha-1; N4, 400 kg ha-1) on maize (Zea mays L.) Results showed that intercropping and increasing N application could enhance green leaf area per maize plant and chlorophyll content, and differences in green leaf area per plant and chlorophyll content between intercropping and monoculture under N1 were significant. Intercropping and increasing N application could improve maize photosynthetic characters, but their effects would be decreased with increasing N fertilization level. Root bleeding sap rate and root DM of maize were also obviously affected by intercropping and N fertilization, and the differences in root bleeding sap rate and root DM between I2 and M under N1 and N2 were significant. Compared to M, under N1, N2, N3, and N4, I2 increased grain N content by 12.8%, 6.3%, 2.7%, 1.5%, respectively. Intercropping and increasing N application could increase maize yield, and the difference in yield between I2 and M under N1 was significant. All the findings suggest that intercropping and increasing N application can improve maize physiological characters and increase maize root DM, N accumulation and yield, but their effects will be decreased with increasing N fertilization level. <![CDATA[<b>Effects of fertilization regimes on tea yields, soil fertility, and soil microbial diversity</b>]]> Fertilization is an important agricultural practice for increasing crop yields and influencing soil properties. A field experiment was conducted in the period of 2006-2011 in southeastern China, to investigate the effects of fertilization regimes on tea (Camellia sinensis [L.] Kuntze) yields, soil chemical properties, and soil bacterial and fungal communities. The field experiment included six treatments: (1) unfertilized control (CON); (2) chemical fertilizers (NPK); (3) half-chemical fertilizers plus half-organic manure (1/2NPKOM); (4) organic manure fertilizers (OM); (5) half-chemical fertilizers plus half-organic manure plus legume stover returned (1/2NPKOM+L), and (6) chemical fertilizers plus legume stover returned (NPKL). Results showed that, compared to the control, NPK treatment showed no significant effect on soil organic matter (SOM), total N (TN), total P (TP), total K (TK), available N (AN), available K (AK) and tea yields, but showed the lowest bacterial Shannon index of 1.714 and the lowest value of 2.002 for fungal Shannon index. Organic manure treatment had the richest diversity of soil bacterial community with Shannon index of 2.542, and the highest levels of soil essential nutrients, including SOM (30.03%), TN (2.90 g kg-1), TP (1.35 g kg-1), AN (245.30 mg kg-1), AP (57.00 mg kg-1), and AK (271.80 mg kg-1), followed by 1/2NPKOM+L, which appeared the maximal tea yields of 6772 kg ha-1. Organic manure amendment was a key factor in determining soil properties and productivity. Base on soil quality and tea yields, both OM and 1/2NPKOM+L treatments were recommended as better choices of fertilization practices for tea soils in southeastern China. These findings provided a better understanding of the importance of fertilizations in promoting soil fertility, crop yields, and altering soil microbial diversity, leading to selection of scientific fertilization practices for sustainable development of agroecosystems. <![CDATA[<b>Morphophysical pedotransfer functions for groundwater pollution by nitrate leaching in Central Chile</b>]]> Nitrate leaching (NL) is a major concern in agriculture due to its impact on human health and ecosystems. Solute movement through soil is governed by various hydraulic and physical properties that determine water flow. To study such relationships, a pedotransfer function of groundwater pollution was developed in two alluvial irrigated soils under long-term pig slurry applications. Two basins of central Chile, San Pedro (Typic Xerochrepts) and Pichidegua (Mollic Xerofluvents) were selected, where maize (Zea mays L.) was grown in spring-summer, while during autumn-winter period a ryegrass-barley-oat mixed crop was established in San Pedro and a fallow management applied in Pichidegua. Soils in cultivated and control sites were characterized in physical and hydraulic terms. Nitrogen and water budgets were determined measuring periodically (biweekly) N concentration (N-NO3- and N-NH4+) and monitoring water contents in soil profiles, respectively. Dye tracer tests were performed with brilliant blue (BB) dye and the staining patterns analyzed. To contrast the effect of slurry additions over soil physical properties and over NL, t-Student tests were performed. Some accurate pollution groundwater NL pedotransfer functions were obtained calculated through least square fit models and artificial neural networks. Textural porosity, mean diameter variation, slow drainage porosity, air conductivity at 33 kPa water tension and N-NO3- concentrations were directly related to NL. In terms of preferential flow analysis, stained path width > 200 mm was inversely associated to NL. Finally, dye tracer tests provided a better understanding of the characteristics and pattern of water/solute movement through soil to groundwater. <![CDATA[<b>Floral transition in <i>Origanum vulgare </i>L.</b>: <b>Anatomical analysis across phenological stages in response to different photoperiodic regimes</b>]]> Knowledge about the specific characteristics of floral transition process in oregano (Origanum vulgare L.) is scarce. Photoperiod is one of the environmental factors regulating oregano development. The aim of this study was to evaluate anatomical changes associated with the phenological transition from vegetative to floral stages of O. vulgare L. subsp. vulgare (Compacto ecotype) and O. vulgare L. subsp. hirtum (Link) Ietsw. (Criollo ecotype), in response to day length variations. These two traditional subspecies were grown under natural and artificially 6-h extended photoperiod. Phenology and internal floral transition did not follow a single evolution pattern, since these processes respond to complex gene-environment interactions. In the oregano subspecies studied, transition from vegetative to reproductive stages presented an intermediate step, consisting of the formation of an inflorescence meristem. Thus, floral transition occurred gradually and acropetally along the floral axis. Within the floral meristem, the appearance of reproductive perianthic pieces also occurred acropetally. Extended photoperiod seemed to act as a signal accelerating the floral transition process of the meristems, which confirms that oregano is a long-day plant. In addition, phenological and anatomical analyses confirmed that Criollo ecotype was most sensitive to photoperiodic lengthening, as evidenced by an earlier bud development all along the floral branch. <![CDATA[<b>Genetic variability assessment in the genus <i>Passiflora </i>by SSR markers</b>]]> The genus Passiflora encompasses many species that are endemic to the Brazilian territory, including some with economic value. Studies on genetic diversity in this genus are fundamental because they allow understanding genetic variability and distance. The present study aimed to determine the genetic variability and distances among 10 species of the genus Passiflora by using microsatellite markers (Simple Sequence Repeat, SSR). Twenty-eight heterologous microsatellite markers were tested, but only 12 were used in the diversity analysis because they amplified in at least 80% of the species. A clear separation was observed among the subgenuses studied, as well as wide variation among the accessions of Passiflora. This knowledge enables breeders to explore diversity and transfer favorable alleles found in wild species. <![CDATA[<b><i>Palmistichus elaeisis </i></b><b>(Hymenoptera: Eulophidae) as an indicator of toxicity of herbicides registered for corn in Brazil</b>]]> The diversity of plants in agricultural systems benefits natural enemies. Herbicides are used in weed management in corn (Zea mays L.) to reduce competition and productivity losses, but they can impact natural enemies and contaminate the environment. The objective was to evaluate toxicity of herbicides on pupae parasitoid Palmistichus elaeisis Delvare and LaSalle, 1993 (Hymenoptera: Eulophidae). The treatments were represented by the host pupae Tenebrio molitor L., 1785 (Coleoptera: Tenebrionidae) and herbicides atrazine, nicosulfuron, paraquat, and tembotrione in commercial doses compared to a control treatment with water. Pupae of T. molitor were immersed in the solution of herbicides and exposed to parasitism by six females of P. elaeisis each. The herbicides atrazine and paraquat were highly toxic and, therefore, not selective to P. elaeisis. Nicosulfuron reduced the sex ratio of P. elaeisis (0.20 ± 0.03), which may affect subsequent generations. Moreover, the herbicide tembotrione was selective to P. elaeisis, showing results comparable to the control. Floristic diversity of weeds can increase food source, habitat, shelter, breeding places and microclimates for insect parasitoids but herbicides formulations can be toxic and these products can affect P. elaeisis or its hosts by direct or indirect contact, showing the importance of selectivity studies for this natural enemy. However, the herbicide tembotrione was selective to P. elaeisis and it can be recommended for programs of sustainable management of weeds in corn crop with this parasitoid. <![CDATA[<b>Beef production from dairy bulls under two different production systems and its effect on the fatty acid profile and beef quality</b>]]> Bulls in dairy production are usually slaughtered at an early age to avoid production problems and unnecessary costs. However, the animals could be a source of additional income and better quality meat. The objective of this work was to determine the characteristic and quantity of fatty acids of the Longissimus thoracis muscle of dairy bulls finished at pasture and in an intensive feeding system. Sixteen 14-mo old Holstein Friesian dairy bulls with initial live weights (LW) of 340 ± 20 kg were randomly assigned to bulls with daily pasture silage and kale (Brassica oleracea L.) supplements and 1.0% concentrate at pasture (T1) and bulls with pasture silage supplements and 2% concentrate in confinement (T2). No differences (P &gt; 0.05) were found between treatments for dressing percentage, rib eye area, and fat cover when animals were slaughtered at 21-mo, with LW 550 kg. However, kidney fat for T1 and T2 of 4.44 and 2.61 kg an-1, respectively, were different (P < 0.05) as was pH, where T2 had a higher value (5.72) than T1 (5.46). Significant differences (P < 0.05) between treatments were found for all polyunsaturated fatty acids (PUFA), conjugated linoleic acid (CLA) c-9, t-11, C18:2 n-6 trans, C18:3 n-3, C22:5 n-3, C22:6 n-3, with higher levels for T1. Beef from the forage-fed bulls (T1) had an n-6: n-3 ratio below 4.0.