Scielo RSS <![CDATA[Chilean journal of agricultural research]]> vol. 77 num. 4 lang. en <![CDATA[SciELO Logo]]> <![CDATA[Gas exchange, photosynthetic pigments, and growth in tomato: lettuce intercropping]]> ABSTRACT The intercropping system is characterized by interspecific competition and leads to one of the most limiting abiotic factors for high plant yield in this cropping system. Plants under low light can carry significant weight in physiological parameters that can limit growth. Light is one of the abiotic factors that limits productivity; in the present study, it was hypothesized that tomato (Solanum lycopersicum L.) and lettuce (Lactuca sativa L.) intercropping in different transplanting periods promotes changes in gas exchange, photosynthetic pigments, and biomass accumulation in two lettuce cultivars. An experimental study was carried out in Jaboticabal, Sao Paulo, Brazil. The treatments consisted of a combination of the following factors: lettuce (one ‘Lucy Brown’ plant between two tomato plants and two ‘Vanda’ plants between tomato plants), two cultivation systems (intercropping and monoculture), and four lettuce transplanting periods (0, 7, 14. and 21 d after tomato transplanting). The experiment was a randomized block with a 3 × 2 × 4 factorial design and four replicates. Transpiration and stomatal conductance were reduced in lettuce by insterspersing plants under a monoculture system. Lettuce-tomato intercropping severely reduced photosynthesis, fluorescence, chlorophyll pigment content, and DM accumulation. Therefore, ‘Vanda’ is better than ‘Lucy Brown’ for intercropping with tomato. <![CDATA[Correlation between grain quality of foxtail millet ( <em>Setaria italica</em> [L.] P. Beauv.) and environmental factors on multivariate statistical analysis]]> ABSTRACT Quantifying the effects of environmental conditions on grain quality of foxtail millet (Setaria italica [L.] P. Beauv.) is critical for large-scale promotion of high-quality foxtail millet according to local conditions. We analyzed quantitative correlation between grain quality of foxtail millet and environmental factors during the growing season (May-September) using multivariate statistical analysis under different ecological conditions at five representative locations across Shanxi Province, China. Based on the results of principal component analysis, the first principal component, which explained 58.22% of total variance in grain quality, was selected to represent the comprehensive quality of foxtail millet. The results of gray relational analysis showed that the difference in grain quality across different locations was mainly affected by altitude (grey relational grade [GRG] = 0.8137), followed by precipitation (GRG = 0.7744), diurnal temperature range (GRG = 0.6816), latitude (GRG = 0.5417), sunshine hours (GRG = 0.5052), and ≥ 20 °C accumulated temperature (GRG = 0.4517). The precipitation of July and diurnal temperature range of July-September had the greatest effect on grain quality of foxtail millet. Stepwise regression and path analyses revealed that altitude, precipitation, and ≥ 20 °C accumulated temperature were the major environmental factors affecting grain quality of foxtail millet, which determined 99% of total variance in grain quality. Altitude and precipitation exhibited a significant positive effect, while ≥ 20 °C accumulated temperature showed a significant negative effect. The regression equation proposed in this study (P = 0.0048, R2 = 0.99) can be used to predict and forecast grain quality of foxtail millet. <![CDATA[Multiple resistance to thifensulfuron-methyl and fomesafen in redroot pigweed ( <em>Amaranthus retroflexus</em> L.) from China]]> ABSTRACT Redroot pigweed (Amaranthus retroflexus L.) is a troublesome weed infesting soybean (Glycine max [L.] Merr.) productions in China. One redroot pigweed population, collected from Heilongjiang (HLJ) Province, China, was suspected to be resistant to thifensulfuron-methyl and fomesafen. The other one redroot pigweed population, collected from Shandong (SD) Province, was susceptible. The study aimed to characterize the level of thifensulfuron-methyl and fomesafen resistance using HLJ population and identify the potential resistance mechanisms to thifensulfuron-methyl. The sensitivity to other herbicides with and without the same target site was also evaluated. Acetolactate synthase (ALS) gene sequencing revealed that Trp574Leu or Ala205Val amino acid substitution were present in the HLJ population. Whole-plant herbicide bioassays showed that, compared with SD population, HLJ population displayed high level of resistance to thifensulfuron-methyl and moderate resistance to fomesafen. The 50% growth reduction (GR50) value of thifensulfuron-methyl with malathion pretreatment was reduced by 23%, suggesting that both target-site resistance and non-target-site resistance mechanisms were present in thifensulfuron-methyl resistance of redroot pigweed. Cross-resistant patterns showed that the HLJ population evolved resistance to pyrithiobac-sodium, pyroxsulam, imazethapyr and fluoroglycofen, but susceptible to bentazone. <![CDATA[Trichoderma strains as growth promoters in Capsicum annuum and as biocontrol agents in Meloidogyne incognita]]> ABSTRACT The Trichoderma species act as plant symbionts, decomposers of organic material, and as antagonists of root phytoparasites. To estimate the potential of four native strains of Trichoderma as growth promoters of Capsicum annuum L. and as biocontrol against root knot nematode Meloidogyne incognita (Kofoid and White) Chitwood, two bioassays in greenhouse were established. In one, the capacity of Trichoderma to promote initial growth of seedlings (36 d after planting, dap) was evaluated. In the other, the biocontrol of Trichoderma against M. incognita at 96 dap was also evaluated. The Trichoderma strains and the chemical fertilization treatment significantly promoted seedling growth at 36 dap (P ≤ 0.01). With respect to the control, T. atroviride promoted greater height in the seedlings, while T. atroviride, T. virens and T. harzianum-C2 increased fresh weight in roots (60.14%) and both T. atroviride and T. harzianum-C2 produced up to 82.30% more dry root biomass. In biocontrol, the control plants registered the highest damage with galling indexes of 85.50% (P ≤ 0.01). The lowest galling indexes were estimated with all the Trichoderma strains (21.60% to 35%). Trichoderma atroviride reduced egg production by 63% and the production of females by 14.36%, with respect to the oxamyl nematicide. Biocontrol of the nematode through the application of the Trichoderma strains favored growth of the plants in general. The fungal species studied show potential as growth promoting agents and as biocontrol agents M. incognita in C. annuum. <![CDATA[Genetic and biological characterization of <em>Macrophomina phaseolina</em> (Tassi) Goid. causing crown and root rot of strawberry]]> ABSTRACT In recent years, crown and root rot of strawberry (Fragaria ×ananassa Duchesne ex Rozier) caused by Macrophomina phaseolina (Tassi) Goid. has affected strawberry production areas worldwide, and in developed countries its emergency has been attributed to the replacement of methyl bromide. The disease was reported in strawberry crop in Chile in 2013, in fields without fumigation. The use of resistant cultivars rises as an alternative to the management of this disease. The objective of this study was to perform a biological and molecular characterization of isolates obtained from two growing regions in Chile and Spain. A total of 35 isolates were characterized for mycelial growth at different temperatures and for chlorate sensitivity. Seven simple sequence repeat loci were used for genetic characterization. Differences were found between Chilean and Spanish isolates in both characterizations. The optimal temperature for mycelial growth was lower in Chilean than in Spanish isolates (30 and 35 °C, respectively). Meanwhile, Chilean isolates were more sensitive to chlorate. In terms of genetic characterization, Polymorphism Information Content (PIC) ranged from 0.38 to 0.85, two main groups were identified, the first group included Spanish isolates and the second group corresponded to Chilean isolates, results were supported by a population structure analysis. This study determined clear differences between two populations of Chilean and Spanish M. phaseolina isolates as causal agent of crown and root rot of strawberry. <![CDATA[Assessment of the genetic variation in alfalfa genotypes using SRAP markers for breeding purposes]]> ABSTRACT The molecular diversity studies of alfalfa (Medicago sativa L.) germplasm could contribute to a more precise selection of parental populations in many breeding programs. Sequence-related amplified polymorphism (SRAP) markers were used to assess the genetic diversity of 110 individual plants from 13 selected alfalfa cultivars, landraces, and natural populations from Tunisia, Australia, Serbia, and Kazakhstan. Ten polymorphic SRAP primer combinations generated 137 alleles with 0.90 polymorphism information content. The percentage of polymorphic bands per genotype ranged from 57.66% to 70.07% with a mean of 64.29% and overall value of 100%. The genotype Sardi 10 had the highest value for the effective number of alleles; Nei’s gene diversity and Shannon information index, exhibited the highest variability level (Ne = 1.453, He = 0.259, I = 0.381, respectively), whereas the genotype Nera exhibited the lowest variability level (Ne = 1.359, He = 0.211, I = 0.317, respectively). The AMOVA analysis showed that 68% of the variance was within the genotypes; this was in line with the coefficient of genetic differentiation (Gst = 0.370). The genetic relatedness of alfalfa individuals analyzed by the neighbor-joining dendrogram was consistent with the Bayesian model-based clustering approach. The exceptions were individuals from genotypes Slavija and Nera, which were grouped separately by STRUCTURE analyses. These results provide useful information for the management of alfalfa genetic resources and the rational use of local and foreign alfalfa populations in breeding programs focused on the development of new, high-yielding cultivars more adapted to drought conditions in North Africa. <![CDATA[Nutritional value, performance, feeding behavior and serum biochemical profile of sheep fed with alfalfa hay replacing Bermuda grass ( <em>Cynodon dactylon</em> (L.) Pers.) hay]]> ABSTRACT Grasses and legumes are two groups of plants physic and chemically different (amount of crude protein and fiber, mostly), very used in animal feed, whose differences can determine variation in intake, digestibility and animal behavior. We aimed to evaluate performance, feeding behavior and the serum biochemical profile of sheep. The treatments were four levels of substitution of Bermuda grass (Cynodon dactylon [L. ] Pers.) hay for alfalfa (Medicago sativa L.) hay (0, 330, 660 and 1000 g kg-1 DM). The randomized block design was used being two blocks and four treatments with 10 replicates). There were no effects on the performance of animals. On the other hand, there was a positive linear effect (P &lt; 0.05) for intake of DM, organic matter, crude protein (CP), total carbohydrates, and non-fibrous carbohydrates. However, the use of neutral detergent fiber (NDF) showed linear decrease with the increase in alfalfa hay (P &lt; 0.05). CP and NDF decreased linearly (P &lt; 0.05) with the replacement of Bermuda grass hay for alfalfa hay. There were decreasing linear effects (P &lt; 0.05) when compared to the time of ingestion and chewing of feed, and increasing linear effects regarding total resting time. Estimated passage rate, density of particles and blood glucose showed a positive linear effect (P &lt; 0.05), while weight of gastrointestinal contents decreased according to alfalfa levels (P &lt; 0.05). The replacement of Bermuda grass hay by alfalfa hay to promote improvement in the performance is not recommended. <![CDATA[Effect of different supplemental irrigation strategies on photosynthetic characteristics and water use efficiency of wheat]]> ABSTRACT Water resource scarcity has been increasingly becoming a threat to wheat (Triticum aestivum L.) production in North China Plain. Thus, a water-saving irrigation strategy should be urgently developed. We conducted a 2-yr field experiment to examine the effects of supplemental irrigation (SI) on the photosynthetic characteristics and water use efficiency (WUE) of wheat. This study employed two SI strategies: A quota SI using 60 mm water at jointing and anthesis stages (W1) and soil moisture testing SI (W2), which brings the target relative soil water content of 0-40 cm soil layer to 70% field capacity at jointing and anthesis stages. A non-irrigated treatment (W0) was used as control. Results showed that W2 significantly improved the water uptake in 80-160 cm soil layer compared with W1. Moreover, flag leaf photosynthetic rate, stomatal conductance, and transpiration 14-28 d after anthesis were highest in W2 successively followed by W1 and W0, and the difference was significant. Dry matter (DM) at maturity, DM accumulation post-anthesis and its contribution ratio to grain were significantly higher in W2 than in the other treatments. 13CO2 labeling results indicated that W2 promoted δ13C-photosynthate accumulation in grain. In 2012-2013 growing season, the grain yield increased by 56.05% and 5.74% and WUE increased by 26.17% and 6.34% in W2 compared with those in W0 and W1, respectively. In 2013-2014 growing season, the grain yield increased by 41.82% and 5.90% and WUE increased by 28.24% and 13.03% in W2 compared with those in W0 and W1, respectively. Therefore, W2 is a high-yield and water-saving treatment. <![CDATA[Soil fungal communities in tea plantation after 10 years of chemical <em>vs</em> . integrated fertilization]]> ABSTRACT Addition of livestock manures and plant residues is a feasible practice to largely mitigate soil-degradative trends by the soil-dwelling fungi. However, long-term impacts of these fertilization regimes on the fungal community are poorly documented in tea (Camellia sinensis (L.) Kuntze) plantations in subtropical areas. In this study, MiSeq sequencing approach was used to estimate the diversity and composition of fungal communities in soils treated with 10 yr of non-fertilization control (CK), chemical fertilizers only (CF), and integrated use of chicken manure and legume straw with chemical fertilizers (IF), respectively. We found that different fertilization treatments produced little effect on the richness and diversity of soil fungi compared to those of the controls. In addition, Ascomycota, Basidiomycota, Zygomycota, Glomeromycota, and Chytridiomycota were the five most abundant phyla in soils under different fertilization treatments. Moreover, IF resulted in the prevalence of the genera Fusarium, unclassified Microascaceae, and unclassified Ascomycota, which accounted for 30.04%, 18.77%, and 6.92% of the total fungi, respectively. Additionally, the relative abundance of the phylum Ascomycota was positively correlated with pH, total N (TN), soil organic C (SOC), soil moisture (SM) and silt (SI) contents; however, these soil physicochemical properties were negatively correlated with the relative abundance of the phylum Basidiomycota. Together, these results suggest that the changes of the fungal community structure at the genus and phylum level under IF treatment could be the result of their responses to variations of soil pH, SM, TN, SOC, and SI contents. <![CDATA[Substitution and optimization of Nigerian white beniseed ( <em>Sesamum indicum</em> L.) cake for soybean meal in Cobb broiler diets]]> ABSTRACT Due to competition between humans, industry and livestock for crop usage, there is need to identify alternative plant protein sources readily available and inexpensive. Beniseed (Sesamum indicum L.) cake is considered to replace soybean (Glycine max [L. ] Merr.) meal as plant protein source for animal feed. This study was conducted to evaluate substitution effects of Nigerian white beniseed cake (BSC) for soybean cake (SBM) in diets of broilers, and determine optimum substitution levels. Replacement levels of BSC for SBM in diets were 0%, 25%, 75%, and 100%. A 56-d feeding trial was conducted on 264-d old unsexed Cobb broilers, randomly assigned to four treatment groups of 66 birds each, with three replicates of 22 birds each in a completely randomized design. A quadratic type optimization function was used to determine optimum BSC levels that significantly affected growth, carcass and blood indices. Diets 100% BSC had the least body weight at 28 d, final body weight, average daily feed intake (ADFI), and carcass weight (P &lt; 0.05). Diets with 25%, 75% and 100% BSC had higher efficiency factor, abdominal fats and white blood corpuscles than 0% substitution diet (P &lt; 0.05). Diet 25% BSC showed significantly higher dressing percentage (P &lt; 0.05), and diet 0% BSC had higher serum protein and urea compared to the other diets. The quadratic function indicated that ADFI was significantly optimized at 25% BSC+75% SBM, with R2 = 0.992 and P-value 0.051. The threshold of 25% to 75% substitution levels of BSC can replace SBM in the diets of Cobb broilers without detrimental effects. <![CDATA[Changes in concentration of volatile compounds in response to defoliation of Muscat of Alexandria grapevines grown under a traditional farming system]]> ABSTRACT Linalool is a monoterpene, which exhibits floral and spicy aromas as well as a variety of pharmacological effects, including antioxidant, anti-inflammatory, and cardiovascular. Wine flavor is highly dependent on the chemical compounds of berries. The objective of this study was to evaluate the concentration of volatile compounds, especially linalool, in grapes (Vitis vinifera L.) ‘Muscat of Alexandria’ grown under different cluster light exposure. Four defoliation treatments were applied at veraison, and changed the light environment at the fruit zone. Severe defoliation (T1): leaves were manually removed from the 1st to the 8th node of each shoot, partial defoliation (T2): leaves were manually removed from the 1st to the 4th, semi-shaded clusters (T3): un-trimmed vines were covered with an 80% shade netting; and (T4) control treatment with non-intervention during season 2014-2015. Free terpenes were extracted using headspace solid-phase microextraction (HS-SPME), and the concentration of volatile compounds was determined using gas chromatography coupled to a flame ionization detector (GC-FID). The study was conducted in two different locations of the Itata Valley in Chile. Linalool concentration was more prevalent in treatments with higher cluster exposure. The treatment with the highest defoliation showed a linalool concentration 40% higher than the control treatment. Higher levels of defoliation in grapevines grown under a traditional farming system result in an increased concentration of volatiles compounds, particularly monoterpenes, where Cerro Verde and Pinihue reached linalool concentrations of 19.1 and 21.7 (g L-1, respectively. These results revealed important differences in the behavior of the synthesis of linalool. <![CDATA[Maize stover biochar increases urea ( <sup>15</sup> N isotope) retention in soils but does not promote its acquisition by plants during a 4-year pot experiment]]> ABSTRACT Biochar as a soil amendment has been shown to improve soil quality and crop growth. However, biochar’s effect on urea-N use efficiency in long term is not well elucidated. Here we studied urea-N (15N isotope) allocation in plants and soil in the presence of maize (Zea mays L.) stover biochar (equivalent to 46 t ha-1) during a 4-yr pot trial. Results showed that biochar only increased maize biomass (about 9%) with high amount of urea addition, which indicates the increased maize dry weight by biochar application could be attributed to synergistic effects between biochar and urea. Soil total N contents and fertilizer N retention were increased by 20% and 10.47% to 94.52%, respectively, indicating that biochar was more capable for fertilizer N retention than promote plant adsorption. Moreover, inorganic N content in biochar treatment was greatly increased, which implies the increased N mineralization. In total, we concluded that biochar application was a potential urea enhancer during plant production. <![CDATA[Pelletized paper mill waste promotes nutrient input and N mineralization in a degraded Alfisol]]> ABSTRACT Pulp and paper mill waste, such as biomass fly ash and sewage sludge, is commonly disposed of in landfills. This waste can be valuable as nutrients and C sources for degraded soils. Ash and sludge samples were chemically characterized before ash/sludge pellets were experimentally manufactured for use as soil amendment. An incubation experiment was carried out with controlled moisture and temperature; nutrient input and N mineralization were evaluated at 0, 15, 30, 45, and 60 d intervals using three pellet types with different proportions of ash, sludge, and gypsum (as a binder) and applied at four doses equivalent to 0, 10, 20, and 40 Mg ha-1. Results indicated that the Alfisol that was amended with pelletized residues increased P Olsen and exchangeable K and Ca contents, as well as soil pH (p &lt; 0.05) in direct response to the applied doses. Organic matter decreased during incubation at all the doses and pellet types (p &lt; 0.05); however, N mineralization did not show a clear pattern during incubation. Nitrogen mineralization potential (N0) was different depending on pellet types and application rates; Pellet 2 (10% sludge) exhibited the highest N0 values, while Pellet 3 (20% sludge) had lower N0 than the control. Pulp and paper mill waste can be used to amend degraded soils by creating sustainable use through pelletizing because it facilitates transport and can evenly distribute sludge and ash on soils in a single application. <![CDATA[Nitrogen mineralization in an Alfisol amended with thermoelectrical industry by-products]]> ABSTRACT In thermoelectric industry, synthetic gypsum and coal ash are generated as industrial by-products. The objective of this work was to evaluate the effect of different mixtures of synthetic gypsum and coal ash on N mineralization in an Alfisol. Nitrogen mineralization was evaluated by soil incubations under controlled conditions and potential mineralization using the nonlinear first order kinetics model Nmt = N0 [1 - ℮(-k t )] , where Nmt is the mineral N accumulated at a specific time, N0 is the potentially mineralizable N, k is the mineralization rate, and finally t is the incubation time. Treatments consisted of different mixtures of synthetic gypsum, coal ash and urea (M1: 50% synthetic gypsum, 50% coal ash, M2: 50% synthetic gypsum, 35% coal ash, 15% urea, M3: 45% synthetic gypsum; 40% coal ash, 15% urea, M4: 65% synthetic gypsum, 20% coal ash, 15% urea, M5: 55% synthetic gypsum, 30% coal ash, 15% urea). Each mixture was applied to the soil at 2 t ha-1. The results shown the highest concentration (p &lt; 0.05) of net mineral N (NMN) applying M3 (166.14 mg kg-1), while the lowest NMN (p &lt; 0.05) was found applying M5 (98.30 mg kg-1). Treatment M1 presented the highest N0 value (579.0 mg kg-1) respect to treatments with urea in its composition, with exception of M3 (523.4 mg kg-1). Where the highest and lowest k were determined in M5 (k = 0.44990) and M3 (k = 0.04470), respectively. Mixtures of synthetic gypsum, coal ash and urea increased N mineralization over mixtures without urea. Respect N potential mineralization, in some cases N0 and k values would respond more to the fit of the mathematical model employed than to the biological process. <![CDATA[Characterization of tirsification soil weathering processes: The case of Los Lirios wetland, Guadalquivir basin, Seville, Spain]]> ABSTRACT The "Andalusian Black Lands" (Chromatic Vertisols) are soils of great ecological and productive importance, emphasizes their fertility, however, their formation is still a reason for discussion. The main objective of this work was to analyze the most recent geomorphological and environmental evolution and the physical-chemical behavior of some parameters along its profile (Chromatic Vertisols). This study was conducted in Los Lirios wetland of the Guadalquivir basin (Seville, Spain). In addition, samples were obtained in an exploration of the bottom of this wetland for a study on pollen. Samples were obtained to a depth of 260 cm every 6 cm in the 120 cm upper soil layer. Physicochemical characteristics of samples were determined in the laboratory. A total number of 20 samples were evaluated, 11 of which correspond to the 65 cm of compact horizons submitted to tirsification. Radiocarbon dating (C14) was performed by Beta Analytic (Miami, Florida, USA). The results indicate the formation of a cumulative glacis and a subsequent environmental change towards more hydromorphic conditions might account for the surface and physical-chemical processes that characterize this alterological process, which generates soils of high ecological significance and agricultural productivity. <![CDATA[Laboratory rearing methods that promote inbreeding have a negative impact on the fitness of <em>Mastrus ridens</em> Horstmann (Hymenoptera: Ichneumonidae), a parasitoid used to control the codling moth]]> ABSTRACT Classical and augmentation biological control depend on the successful laboratory rearing of natural enemies, but rearing methods can affect the success and productivity of a laboratory colony. One process that can occur during rearing is the loss of genetic variability due to inbreeding. The aim of this study was to examine the influence of rearing methods with and without inbreeding in Mastrus ridens Horstmann, a hymenopteran parasitoid specialist of the codling moth (Cydia pomonella (L.(), on several fitness traits. Traits of females from mixed and endogamous populations resulting from different rearing methods were compared, as well as traits of females from the same population subjected to sib-mating or outbreeding. Longevity, parasitism, total fecundity, and number of sons were similar for females in both evaluations. The number of daughters was lower (1.9 ± 0.6 vs. 4.5 ± 0.5) and the offspring sex ratio was higher (0.81 ± 0.04 vs. 0.48 ± 0.05 proportion of males) in females from the endogamous population compared to females of the mixed population, as well as in sib-mating females compared to outbred females of the same population (0.5 ± 0.3 vs. 5.8 ± 1.9 daughters and 0.94 ± 0.03 vs. 0.51 ± 0.10 sex ratio). These results show that rearing methods, specifically inbreeding conditions, have an effect on M. ridens fitness; thus, successful outbred laboratory rearing should be promoted.