Scielo RSS <![CDATA[Chilean journal of agricultural research]]> vol. 73 num. 1 lang. en <![CDATA[SciELO Logo]]> <![CDATA[<b>Cold tolerance evaluation in Chilean rice genotypes at the germination stage</b>]]> Low temperature is the most important abiotic stress affecting rice (Oryza sativa L.) yield in Chile. Rice in Chile is usually planted when the minimum air temperatures are below 12 °C. This temperature is lower than the optimum needed for normal rice germination. Therefore, the aim of this study was to evaluate cold tolerance in 20 experimental lines from the Rice Breeding Program of the Instituto de Investigaciones Agropecuarias (INIA), Chile, at the germination stage. Coleoptile length reduction (CRED), coleoptile length after cold treatment (CLEN), coleoptile length recovery (CREC), and coleoptile regrowth (CREG) were evaluated at 13 °C for 4 d using &rsquo;Diamante-INIA&rsquo; as the cold-tolerant control. To find genotypes with cold tolerance (low CRED value and high CLEN, CREC, and CREG values), genotypes were ranked, a biplot of principal components, and cluster analysis were performed. No differences were found among genotypes in the ranking based on CREC value so this trait was not considered. Analysis showed that only three experimental lines had cold tolerance similar to that of &rsquo;Diamante-INIA&rsquo;; all other experimental lines exhibited intermediate to low cold tolerance. These results showed low cold tolerance of some Chilean genotypes at the germination stage, thus confirming the need to evaluate the rest of the germplasm from the Rice Breeding Program. <![CDATA[<b>Gene action and combining ability of yield and its components for late <i>kharif</i> season in okra <i>(Abelmoschus esculentus</i> (L.) Moench)</b>]]> Knowledge on the genetic system controlling the quantitative traits is important for devising an efficient selection program through the use of a suitable mating design. Forty five Fis were generated by crossing 10 germplasm lines of okra (Abelmoschus esculentus (L.) Moench) namely P1(IC282248), P2(IC27826-A), P3(IC29119-B), P4(IC31398-A), P5(IC45732), P6(IC89819), P7(IC89976), P8(IC90107), P9(IC99716), and P10(IC111443) during summer 2009. Forty five F1s along with their 10 parents were evaluated in a randomized block design with three replicates during late kharif (August-November) 2009 at Vegetable Research Station, Hyderabad, Andhra Pradesh, India, for studying gene action and combining ability of yield and its components. Significant general combining ability and specific combining ability variances were obtained in majority of the traits except fruit and shoot borer infestation on fruits and shoots; implying that both the additive and non-additive gene effects operated in the genetic expression of the traits. The relative magnitude of general and specific combining ability variances indicated preponderance of non-additive gene action for majority of the characters studied except number of branches per plant and fruit width. Combining ability analysis of parents revealed that the parental lines P5(IC45732), P6(IC89819) and P7(IC89976) were superior general combiners for total and marketable yield per plant and other traits. The crosses C23(IC29119-B x IC99716), Cn(IC27826-A x IC111443), C42(IC89976 x IC111443) and C43(IC90107 x IC111443) were superior specific combiners for total as well as marketable yield per plant with the potential of being commercially exploited for the production of F1 hybrids. The crosses C17 (IC27826-A x IC111443) and C42(IC89976 x IC111443) involving one or both of the parents with positively significant general combining ability effects for marketable yield per plant could be utilized in recombination breeding. <![CDATA[<b>Microencapsulation of maqui (<i>Aristotelia chilensis</i> Molina Stuntz) leaf extracts to preserve and control antioxidant properties</b>]]> Microencapsulation technology is an alternative to stabilize stress factors and protect food ingredients or additives, which include environmentally sensitive bioactive principles in protective matrices to increase their functionality and life span. The objective of this research was to study conditions to obtain microcapsules with antioxidant capacity from a maqui (Aristotelia chilensis [Molina] Stuntz, Elaeocarpaceae) leaf extract by emulsification and subsequent retention after microencapsulation. Microcapsules were produced by water-in-oil emulsion (W/O) using a phase of the aqueous maqui leaf extract and gum arabic, and a liquid vaseline phase. Maqui leaf extract antioxidant capacity was 99.66% compared with the aqueous phase of the emulsion at 94.38 and 93.06% for 5% and 15% gum arabic, respectively. The mean yield of maqui leaf extract microencapsulation with 5% gum arabic varied between 38 and 48%, whereas with 15% gum arabic it was 39%. Once the antioxidant microcapsules were formed, mean extract antioxidant capacity ranged between 30 and 35%. Both yields responded similarly to changes in gum arabic concentrations (5% and 15%) in the aqueous phase of the emulsion; 5% concentration produced a microcapsule size from 1.0 to 10 urn. Maqui leaf extracts with high phenolic compound levels, which can be stabilized and protected by the microencapsulation process, produce new natural preservative systems as compared with their synthetic counterparts. <![CDATA[<b>Field bindweed <i>(Convolvulus arvensis</i> L.) and redroot pigweed <i>(Amaranthus retroflexus</i> L.) control in potato by pre- or post-emergence applied flumioxazin and sulfosulfuron</b>]]> Field bindweed (Convolvulus arvensis L.) is one of the most serious weeds in potato (Solanum tuberosum L.), but selective herbicides controlling this weed have not been reported. A field experiment was conducted in 2010 and repeated in 2011 in Greece to study the efficacy of herbicides flumioxazin and sulfosulfuron, applied pre- or post-emergence, on field bindweed and redroot pigweed (Amaranthus retroflexus L.), as well as their phytotoxicity on potato. Gas chromatography-mass spectrography (GC-MS) and high-performance liquid chromatography (HPLC) analyses were conducted for possible herbicide residues in potato tubers. Also, the efficacy of these herbicides on field bindweed generated from root fragments was investigated in greenhouse pot experiments. In pots, both herbicides provided 78% to 100% control of field bindweed generated from root fragments. In field, both herbicides when applied pre-emergence at 72 to 144 g ai ha-1 provided 65% to 100% field bindweed control. However, the corresponding post-emergence applications did not provide satisfactory weed control. All treatments provided excellent control of redroot pigweed. Potato growth was not significantly affected by herbicide application in 2010. However, in 2011, post-emergence applications of flumioxazin caused significant crop injury and yield reduction. The results of this study indicate that satisfactory control of field bindweed and redroot pigweed, as well as high potato yield can be obtained by the pre-emergence application of flumioxazin or sulfosulfuron at 72 to 144 g ai ha-1, without herbicide residues on potato tubers. <![CDATA[<b>Phosphorus absorption and use efficiency by <i>Lotus</i> spp. under water stress conditions in two soils</b>: <b>A pot experiment</b>]]> The response to P and water deficiencies of forage Lotus species has not been sufficiently studied in the Andisol and Vertisol soil orders in Chile&rsquo;s marginal areas. A pot experiment under cover was carried out between October 2007 and March 2008 to study the effects of P and soil water availability (SWA) on DM production, P absorption, and P use efficiency in Lotus spp. The experiment included three Lotus (L. corniculatus L., L. tenuis Waldst. & Kit. ex Willd., and L. uliginosus Schkuhr) species, two soils (Andisol and Vertisol), two contrasting P levels (low and high), and two SWA levels (10% and 100%). A completely randomized design with a 3 x 2 x 2 x 2 factorial arrangement with four replicates was used. Accumulated shoot and root DM, P absorption and efficiency, and arbuscular mycorrhizal (AM) colonization were measured. Phosphorus absorption was significantly higher in Andisol with 100% SWA and high P in the three species, which was reflected in P efficiency where the species exhibited higher P absorption efficiency (PAE) and P utilization efficiency (PUE) with low P, and mean of the three species with low P and high SWA. When the P level was low, L. uliginosus showed the highest PAE and L. corniculatus exhibited the highest PUE. Phosphorus efficiency was also influenced by AM colonization since on the average mycorrhization in the three species was significantly higher in the low P treatments. Differences existed among species for DM production, response to P, P absorption, PAE, and PUE. <![CDATA[<b>Seed softening patterns of forage legumes in a temperate/subtropical environment in Uruguay</b>]]> Few studies have been conducted in annual and perennial forage legumes to investigate the development of hardseededness and the subsequent pattern of seed softening in temperate and subtropical regions of South America. Experiments were conducted during 2007 and 2008 in central Uruguay to follow the pattern of seed softening in 35 annual and perennial forage legumes, including three native species of Uruguay and five commercial cultivars. Newly ripened seeds of each plant material were placed in mesh packets on the soil surface in mid-summer. Samples were recovered monthly for germination tests and the proportion of residual hard seeds determined. The native species Adesmia bicolor (Poir.) DC., Adesmia securigerifolia Herter, and Ornithopus micranthus (Benth.) Arechav., together with Ornithopus pinnatus (Mill.) Druce cv. INIA Molles behaved similarly. They showed high levels of initial hard seed from 78% in A. bicolor to 99% in A. securigerifolia and O. pinnatus cv. INIA Molles in 2007; displayed pulses of seed softening, particularly in autumn, and retained moderate levels of residual hard seed for the development of a soil seed bank ranging from 15% in A. bicolor to 49% in O. micranthus. These appear to be desirable characteristics for persistence of forage legumes in subtropical grasslands, both for annual and perennial species. Trifolium repens L. and Lotus corniculatus L. produced few hard seeds, only 2% and 13% respectively were hard after 1-mo in the field and were completely soft by July placing extra reliance on their vegetative propagation for persistence. Materials of L. arenarius Brot. showed pronounced late autumn softening, while materials of L. ornithopodioides L. showed extremely high levels of hardseededness (between 96% and 100%) and no softening during the evaluation period, apart from two materials that were completely soft seeded. Mediterranean forage legumes should be properly evaluated in temperate and subtropical regions as their seed softening behavior is likely to be substantially modified in these summer moist environments. <![CDATA[<b>Effect of breed and feeding on the carcass characteristics of the Chilote breed lamb</b>]]> The Chilote sheep has been developed in an isolated environment, based on grazing lands with low nutritive value belonging to small-scale producers, because of which there is little information about the use of this breed for meat production. The objective of this work was to determine the effects on lamb carcasses of two breeds with different productive purposes and fed on pastures with different nutritional quality. Three groups of lambs were used. The first and second groups were composed of 13 and 11 Chilote lambs respectively, and the third composed of six Suffolk Down lambs. Lambs remained with their mothers, the first group on naturalized pasture and the rest on rangeland. Animals were slaughtered at 90 d of age. Live weight, carcass weight and yield, and several zoometric parameters were determined, as well as the weight of commercial cuts and the muscle, bone and fat ratios. Hide and hoof weights were also measured. For the effect of breed, Chilote lamb is narrower (P < 0.05) than Suffolk Down, but with a higher proportion of hide (P < 0.05) and hooves (P < 0.05). The type of pasture only affected hot carcass yield, which was higher in Chilote lamb with naturalized pasture than with rangeland (P < 0.05). There were no effects of breed or pasture type on the main characteristics of the lamb carcasses. <![CDATA[<b>Effect of soil depth and increasing fertilization rate on yield and its components of two durum wheat varieties</b>]]> Agronomic practices, climatic variables, and soil conditions are key factors in crop productivity. Although the effects of soil chemical properties and water and agronomic crop management are known, there is little information about effective soil depth and its influence on crop productivity. Since most crop fertilization systems are based on the productive potential associated with climatic conditions and chemical properties of the first 20 cm of soil depth, the objective of this study was to determine the importance of effective depth in terms of increasing fertilization rates on durum wheat (Triticum turgidum L. var. durum) productivity. Two experiments were conducted in the 2006-2007 season in the Santa Rosa Experimental Station (71°54&rsquo; S, 36°31&rsquo; W, 220 m a.s.l.) of the Instituto de Investigaciones Agropecuarias (INIA) located in south central Chile. We used the hard wheat cvs. Llareta-INIA and Corcolén-INIA because both respond differently to soil physicochemical properties. Each cultivar was sown in sectors with different depths: 1) 0.45 m depth, silt loam on river material and 2) 1.0 m depth, loam on deep sediments. Fertilization was: 1) control without fertilization, 2) basal fertilization (BF) based on P, K, Ca, Mg, S, B, and Zn plus 90 kg N ha-1, and 3) BF plus 210 kg N ha-1. Grain yield, plant height, and number of stems m-2 were positively affected by increasing depth of soil profile. The increasing fertilization rate affected grain yield and plant height. Grain yield for cv. Corcolén-INIA had a greater response than cv. Llareta-INIA when soil depth was increased. <![CDATA[<b>Investigations of the <i>Plum pox virus</i> in Chile in the past 20 years</b>]]> Sharka disease, which is caused by Plum pox virus (PPV), is one of the most serious diseases affecting stone fruit trees around the world. Identified in Bulgaria in 1931, it was restricted to the European continent until 1992 when the virus was identified in Chile. It was subsequently verified in the USA, Canada, and Argentina. After 20 years since first detecting PPV in Chile, it seems clear that the disease cannot be eradicated in spite of various measures. Considering the seriousness of this problem for the domestic industry, a series of studies have been conducted to determine the distribution and degree of transmission of the disease, its biological and molecular characterization and epidemiological aspects, etc. The available information has allowed national phytosanitary control agencies to take steps to decrease the effects of the virus. However, there is a lack of data with respect to epidemiological factors for a more accurate understanding of the performance of the virus under Chilean conditions. <![CDATA[<b>Cracking in sweet cherries</b>: <b>A comprehensive review from a physiological, molecular, and genomic perspective</b>]]> Rain-induced cracking in fruits of sweet cherry (Prunus avium L.) is a problem in most producing areas of the world and causes significant economic losses. Different orchard management practices have been employed to reduce the severity of this problem, although a complete solution is not yet available. Fruit cracking is a complex phenomenon and there are many factors that seem to be involved in its development. During the last decade, genomic and biochemical approaches have provided new insights on the different mechanisms that could be involved in the differential susceptibility shown by commercial cultivars. For instance, sweet cherry genome and transcriptome sequencing information have provided new opportunities to study the expression and structure of genes involved in cracking, which may help in the development of new tolerant cultivars. The present review summarizes, discuss, and integrate most of the recently generated information in cultural practices, physiology, biochemistry, and genetics in relation to cracking in sweet cherries. <![CDATA[<b>Validation of a leaf area prediction model proposed for rose</b>]]> Leaf area (LA) is a valuable key for evaluating plant growth, therefore accurate, simple, and nondestructive methods for LA determination are important for physiological and agronomic studies. A LA prediction model based on leaf length (L) and width (W) and developed under greenhouse on 14 cultivars of rose (Rosa hybr.*) was validated on a different cultivar of R. hybrida &rsquo;Red France&rsquo; and on a wild rose species (Rosa sempervirens L.) grown under open-field conditions with two light environments: ambient and 50% shade. Comparisons between measured vs. calculated LA using the following model: LA (cm²) = 0.56 + 0.717 LW, showed a high degree of correlation (R² > 0.95) and provided quantitative evidence of the validity of the LA prediction model. Calculated LA values were very close to the measured values, giving an underestimation of 3.5%, 4.2%, 1.1%, and an overestimation of 1.3% in the prediction for R. hybrida ambient light, R. hybrida 50% shade, R. sempervirens ambient light, R. sempervirens 50% shade, respectively. This model can provide accurate estimations of rose LA independently of the genetic materials and the growing conditions and can be adopted in many experimental comparisons without the use of any expensive instruments. <![CDATA[<b>Genetic variation within three populations of <i>Phycella australis</i> (Phil.) Ravenna from Biobío Region, Chile, evaluated using ISSR markers</b>]]> Phycella australis (Phil.) Ravenna is a Chilean plant with high ornamental potential; however, the intensive extraction as a cut flower might be detrimental for the conservational state by ignoring the state of genetic variation. The objective of this investigation was to assess genetic variability within and between three populations of P. australis in the Biobío Region using inter-simple sequence repeat (ISSR) markers. The evaluated areas correspond to three locations in the province of Concepción, Biobío Region: Desembocadura (36°48&rsquo; S, 73°10&rsquo; W), Santa Juana (36°58&rsquo; S, 72°58&rsquo; W), and Lipinhue (37°00&rsquo; S, 72°58&rsquo; W). Six ISSR primers were used obtaining 51 fragments, from which 72.5% were polymorphic. From the three evaluated sites Santa Juana showed a higher percentage of polymorphic loci (76.47%). From this variability, 83% belong to within population variability and only 17% belong to variability between populations. The dendrogram generated using the unweighted pair group method with arithmetic mean (UPGMA) method, grouped Lipinhue and Santa Juana sites together, which agrees with the geographic locations. This investigation proved that P. australis has high genetic variability despite the exploitation for economic purposes.