Influence of drip and furrow irrigation systems on nitrogen oxide emissions from a horticultural crop

Irrigation management has an important influence on emissions of nitrous oxide (N₂O) and nitric oxide (NO) from irrigated agricultural soils. In order to develop strategies to reduce the emission of these gases, a field experiment was carried out to compare the influence of different irrigation systems: furrow (FI) and drip-irrigation (DI), on N₂O and NO emissions from a soil during the melon crop season. Two fertilizer treatments were evaluated for each irrigation regime: ammonium sulphate (AS) as a mineral N fertilizer, at a rate of 175 kg N ha^?1; and a control without any N fertilizer (Control). On plots where the AS treatment was applied, drip irrigation reduced total N₂O and NO emissions (by 70% and 33% respectively) with respect to values for furrow irrigation. This was probably due to the lower amount of water applied and the different soil wetting pattern associated with DI. Dry areas of the drip-irrigated plots emitted a similar amount of N₂O to the wet areas (0.45 kg N₂O-N ha^?1) in the Control and greater quantities in the AS treatment (0.92 kg N₂O-N ha^?1 for dry and 0.70 kg N₂O-N ha^?1 for wet areas). We suggest that the N oxide pulses observed throughout the irrigation period on DI plots could have been the result of frequent increases in the soil wetting volume after the addition of water. Denitrification losses (from depths of 0–10 cm) were estimated at 11.44 kg N₂O- N ha^?1 for the AS treatment under FI and at 4.96 kg N₂O-N ha^?1 for DI. Under DI, nitrification was an important source of N₂O, whereas denitrification was the most important source under FI. The addition of NH₄⁺ and the use of DI enhanced the N₂O/N₂ ratio of gases produced through denitrification. The quantity of dissolved organic C (DOC) in the soil generally decreased with addition of NH₄⁺.This work showed that, in comparison with furrow irrigation, drip irrigation is a method that can be used to save water and mitigate emissions of the atmospheric pollutants NO and N₂O.     

On the origin of artichoke and cardoon from the <Emphasis Type="Italic">Cynara</Emphasis> gene pool as revealed by rDNA sequence variation

The evolutionary history of artichoke and cultivated cardoon and their relationships to wild allies of the genus Cynara are not fully understood yet. To try resolve the evolutionary patterns leading to the domestication of these two crops, a study of molecular evolution was undertaken. The species C. cardunculus, including artichoke, cultivated and wild cardoon, together with four wild Cynara species were taken into consideration. Internal (ITS) and external (ETS) rDNA transcribed spacers were used as markers of nuclear genome, the psbA-trnH spacer as a marker of chloroplast genome. Sequences were analysed using phylogenetic analysis packages. Molecular data indicate that the whole genus is quite recent and that the domestication of artichoke and cultivated cardoon, crops diverging for reproduction system and use, are independent events which diverge in time and space. As for wild Cynara species, an evolutionary pattern consistent with their present geographical distribution was hypothesized in relation to the climatic changes occurring in the Mediterranean during the last 20 millennia: C. humilis and C. cornigera appeared to have differentiated first, C. syriaca and C. baetica were differentiated in a second period, while C. cardunculus showed to be the most recent and plastic species. The high plasticity of C. cardunculus has not only allowed its nowadays wide distribution, but has also given the potential for domestication. Dedicated to the memory of Richard Neville Lester (1937–2006) who greatly contributed to the understanding of the evolution, domestication, and genetic resources of eggplants as well as to the biosystematics and taxonomy of allied species. IGV Publication N. 78 of the Institute of Plant Genetics, CNR     

Is ‘grey literature’ a reliable source of data to characterize soils at the scale of a region? A case study in a maritime pine forest in southwestern France

Soil scientists are receiving increasing numbers of requests for expert advice on soil over large areas, but at a high resolution. We tested the use of the soil data contained in sources of information that are not directly accessible (referred to as ‘grey’ data) to accomplish this task. We collected grey data about a pine forest, which is currently the subject of drastic, and questionable, changes in management, including a rapid rate of biomass removal. These grey data (from 266 sites) were compared with soil data obtained directly from our field sampling (83 sites). Our comparisons showed that the two sources of data were consistent when the variables concerned had been sampled and analysed by using methods shared by the soil scientists such as particle‐size distribution. Conversely, significant discrepancies appeared for variables for which different methods existed, such as for CEC. For the latter, using corrective equations gave contrasting results, depending on the soil variable. The final database was used to characterize the soils of the study region. Results showed that soils of the study region (mainly sandy podzols and arenosols) were acidic and particularly oligotrophic. Several important properties (CEC, phosphorus cycling, pH, bulk density) were related to the organic fraction or carbon (C) content of soils. For instance, CEC values were linearly and exclusively dependent on C content. The most oligotrophic sites of the study region were clearly not suitable for the new intensive management of the forest in the long term. For the other sites, the question remains open because some specific data are still needed before drawing conclusions. We conclude that as a complement to conventional soil studies, the grey literature is a useful source of data and information to characterize soils at a regional scale.     

Oxytocin-induced PGF2alpha release in mares with and without post-breeding delayed uterine clearance

The aim of the present study was to evaluate within 24 h post-ovulation oxytocin-induced PGF(2alpha) release in mares with and without post-breeding delayed uterine clearance (DUC). Twenty-one of 34 mares with a variable amount of intrauterine fluids accumulation were considered to be affected by delayed uterine clearance (DUC group), while the other 13 mares did not show any uterine fluid accumulation, and were considered as controls (WDUC group). Both DUC and WDUC mares were administered with 20 IU oxytocin i.m. 90 min after the ultrasound examination performed 24 h after breeding. Immediately before, 5 and 10 min after oxytocin administration, blood samples were collected for 15-ketodihydro-PGF(2alpha) (PG-metabolite), 17beta-estradiol, and progesterone analysis. Ultrasonography performed 24 h after oxytocin treatment showed a complete uterine clearance in all DUC mares. The oxytocin-induced PG-metabolite increase was detected in 71.4% DUC mares compared with 38.5% in WDUC group, with a positive trend of release, as evidenced from 5 min after oxytocin administration. In WDUC mares, no significant differences in oxytocin-induced PG-metabolite trend of release were observed. In conclusion, the results of the present study showed the importance of PGF(2alpha) involvement in the pathogenesis of post-breeding DUC in the mare.     

Occurrence of Libyostrongylus sp. (Nematoda) in ostriches (Struthio camelus Linnaeus, 1758) from the north region of the state of Rio de Janeiro, Brazil

Domestic production of ostrich in Brazil started in the beginning of the last decade, but its sanitary state has not been reported. Libyostrongylus sp. is an ostrich specific nematode whose parasitism can severely affect the birds. Thus, Libyostrongylus spp. larvae were identified in commercial ostriches in the north region of the state of Rio de Janeiro, Brazil. The EPG was determined and fecal cultivation was performed. The eggs presented typical characteristics of strongylid and were present in five out of six farms. The mean EPG varied from 22 to 2395 and Libyostrongylus spp. prevalence was from 0 to 100%, with adult birds more infected. Two types of infective larvae with tail finishing in a tipped spiny knob were distinguished. The first had a mean length of 848 microm (710-1010) with a long sheath tail of about 66 microm (52-112). The other had a mean length of 826 microm (620-940) with a short, more abruptly ending sheath tail of 32 microm (22-40) and a less rounded cephalic end. The differences between these larvae suggest two Libyostrongylus species.     

The breeding possibilities and genetic parameters of maize resistance to foliar diseases

The combining ability and genetic parameters of maize grown in two different environments of diseases pressure were estimated for partial resistance to northern leaf blight (Exserohilum turcium, NLB) and gray leaf spot (Cercospora spp., GLS). Nine inbred lines were crossed in a complete diallel mating scheme including reciprocals. Two experiments were carried out to test the hybrids using randomised complete blocks design with three replications during the growing season 2008/2009. The severities of NLB and GLS were assessed under natural infestation conditions. The first experiment was the lowest NLB and GLS pressure environment, whereas the second was the highest. Data was evaluated using individual and joint Griffing’s diallel analyses. General and specific combining abilities were significant (P < 0.10) for NLB and GLS resistance under both pressures. Although additive and nonadditive gene effects were significant, the additive gene effects were more important for resistance to the diseases. The lines 1 (P₈₃), 6 (P_30F) and 7 (P_st) had the most outstanding general combining ability for NLB resistance, and the line 3 (P₈₀) was outstanding for resistance to GLS. Based on both diseases resistance and grain yield, the synthetic composites 6 × 7 × 3 and (6 × 7) × 3 were recommended for intrapopulational breeding using recurrent selection. Three promising hybrid combinations (the 3 × 6, and 5 × 7 for resistance to NLB, and 3 × 9 for resistance to GLS) were recommended for interpopulational breeding. Resistance levels to NLB and GLS resistance were better discriminated under HP than LP conditions; however, promising lines were detected under both pressures.     

Protein supplementation to early lactation dairy cows grazing tropical grass: Performance and ruminal metabolism

This experiment was designed to evaluate the effects of different concentrate crude protein (CP) concentration on performance, metabolism and efficiency of N utilization (ENU) on early-lactation dairy cows grazing intensively managed tropical grass. Thirty cows were used in a ten replicated 3 × 3 Latin square design. The treatments consisted of three levels of concentrate CP: 7.9%, 15.4%, and 20.5% offered at a rate of 1 kg (as-fed basis)/3 kg of milk. The cows fed low and medium CP had negative balance of rumen degradable protein and metabolizable protein. Increasing CP tended to linearly increase DMI, 3.5% FCM and milk casein, and linearly increased the yields of milk fat and protein. Increasing CP linearly increased the intake of N, the concentration of rumen NH₃–N, and the losses of N in milk, urine, and feces. Increasing dietary CP linearly increased the molar proportion of butyrate but had no effect on the other rumen VFAs and no effect on microbial yield. In conclusion, feeding a concentrate with 20.5% of CP to early-lactation dairy cows grazing tropical grasses, leading to a 17.8% CP diet, tended to increase DMI, increased the yield of 3.5% FCM and the milk N excretion, and decreased ENU by 32%.     

Quantitative trait loci analysis of citrus leprosis resistance in an interspecific backcross family of (<Emphasis Type="Italic">Citrus reticulata</Emphasis> Blanco × <Emphasis Type="Italic">C. sinensis</Emphasis> L. Osbeck) × <Emphasis Type="Italic">C. sinensis</Emphasis> L. Osb

Leprosis, caused by citrus leprosis virus (CiLV) and transmitted by the tenuipalpid mite Brevipalpus phoenicis, is one of the most important viruses of citrus in the Americas. Sweet oranges (Citrus sinensis L. Osb.) are highly susceptible to CiLV, while mandarins (C. reticulata Blanco) and some of their hybrids have higher tolerance or resistance to this disease. The mechanisms involved in the resistance and its inheritance are still largely unknown. To study the quantitative trait loci (QTL; quantitative trait loci) associated with the resistance to CiLV, progeny analyses were established with 143 hybrid individuals of ‘Pêra’ sweet orange (C. sinensis L. Osb.) and ‘Murcott’ tangor (C. reticulata Blanco × C. sinensis L. Osb.) from controlled crossings. Disease assessment of the hybrid individuals was conducted by infesting the plants with viruliferous mites in the field. The experiment consisted of a randomized completely block design with ten replicates. The evaluated phenotypic traits were incidence and severity of the disease on leaves and branches, for a period of 3 years. The MapQTL™ v.4.0 software was used for the identification and location of possible QTL associated with resistance to CiLV on a genetic map obtained from 260 AFLP and 5 RAPD markers. Only consistent QTLs from different phenotypic traits and years of evaluation, with the critical LOD scores to determine the presence or absence of each QTL calculated through the random permutation test, were considered. A QTL was observed and had a significant effect on the phenotypic variation, ranging from 79.4 to 84% depending on which trait (incidence or severity) was assessed. This suggests that few genes are involved in the genetic resistance of citrus to CiLV.     

Mesquite pod meal as an additive increases milk total solids,lactose, fat and protein content in dairy cows

The objective was to evaluate the intake, digestibility, milk yield and composition of cows fed mesquite pod meal (MPM). Five crossbred dairy cows, with an average body weight of 450?±?5 kg and producing 10?±?1 kg of milk/day were distributed in a 5?×?5 Latin square arrangement with five periods of 20 days each, comprised of 15 days for adaptation to the experimental diets (T1?=?0%, T2?=?1.5%, T3?=?3.0%, T4?=?4.5% and T5?=?6.0% MPM) and 5 days for data collection. Variables were assessed by analysis of variance and regression at P?<?0.01 and P?<?0.05 of significance, using the Student’s test. Animals were kept on pastures and the concentrates were provided at 6 kg/animal divided in two meals per day. The inclusion of 3.0% mesquite pod meal did not affect the intake, digestibility of nutrients and milk yield, but it changed milk composition. The dietary inclusion of 3.0% mesquite pod meal as a palatability enhancer increases the percentage of milk solids, lactose, fat and protein. Therefore, mesquite pod meal can be included in diets for dairy cows to improve the nutritive value of milk.