Root depth: a trait to increase water use and yield of wheat

Crops with deeper roots could potentially capture more soil resources and as a consequence yield more. However, as sampling roots by soil coring is challenging, there are few examples of genetic diversity determined under field conditions. Canopy temperature, an indicator of transpiration, could be used instead of direct coring to screen for wheat varieties with increased access to deep water and hence deep roots in the field. In this thesis we aimed (i) to seek genetic diversity in rooting depth, root length density and relate these traits to yield in a wide range of triticale and wheat germplasm, and (ii) to test the usefulness of continuously-monitored canopy temperature and soil water status for phenotyping two commercial wheat varieties that differ in rooting depth. In the first set of field experiments, rooting depth, root length density and yield were measured in 34 wheat and 2 triticale varieties. Roots were sampled by soil-coring with a tractor-mounted hydraulic press and were later counted by the 'core break' method. Root length density was predicted from root count density. In the second set of experiments, canopy temperature was measured with fixed infra-red thermometers, and soil water suction was determined with gypsum blocks buried at 20 cm intervals, from 20 to 160 cm depth. A crop water-stress index (CWSI) was calculated to normalise for the effects of vapour pressure deficit over canopy temperature. Soil water retention curves fitted to the soil of the site were used to convert soil water suction into soil water content. Shoot biomass and grain yield were estimated from 0.7 m^2 samples per plot in all experiments. In the experiments seeking genetic variability, we found that triticale produced deeper roots than commercial spring-wheat (p < 0.10), and shorter varieties produced deeper roots than taller varieties (p < 0.10). Moreover, rooting depth was related to shoot biomass (R^2 = 0.66, p < 0.001) and grain yield (R^2 = 0.56, p < 0.001) across experiments and genotypes but not between genotypes within the same experiment. In the experiments analysing canopy temperature and water-use continuously, differences in deep-root length were not statistically significant between the two varieties. The variety Gregory had greater root length at depths beneath 1 m, was cooler, used more water and that water was withdrawn from deeper soil layers than the other variety, Derrimut. Using CWSI gave better predictions of soil water status than canopy temperature per se. By taking up more water during grain filling, Gregory produced more yield at a rate of 54 kg ha^-1 mm^-1 . CWSI did not correlate with day-to-day changes in water use. We conclude that (i) there is genetic diversity in rooting depth within triticale and wheat germplasm; (ii) by enabling the calculation of a CWSI, continuously measured canopy temperature allows phenotyping of root systems with superior deep water access

Wheat Ppd-1 allelic combination modulates photoperiod sensitivity

ABSTRACT: a model linking Ppd-1 allelic composition to photoperiod response curve would allow replacing expensive and time consuming phenologic trials. In Ppd-1 near isogenic lines grown under different photoperiods we observed that Ppd-1a “insensitivity” alleles decreased photoperiod sensitivity for the whole cycle to anthesis, with negligible effect on threshold photoperiod or intrinsic earliness. Photoperiod sensitivity for the first half of the cycle (emergence to onset of stem elongation) responded similarly. Photoperiod response for the second half (onset of stem elongation to anthesis) was milder. After validation, this model would allow to predict photoperiod response of any genotype, given its Ppd-1 allelic combination.EEA PergaminoFil: Perez Gianmarco, Thomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; ArgentinaFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; ArgentinaFil: González, Fernanda. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; Argentin

Photoperiod-sensitivity genes (Ppd-1) : quantifying their effect on the photoperiod response model in wheat

Coupling anthesis date to the most suitable environmental conditions is critical for wheat (Triticum aestivum L.) adaptation and yield potential. Development to anthesis is controlled by temperature and photoperiod. Response to photoperiod is chiefly modulated by Ppd-1 genes, but their effect on the quantitative response to photoperiod of (i) time to anthesis and (ii) pre-anthesis phases remains largely unknown. A photoperiod-sensitive spring cultivar, Paragon, and near-isogenic lines of it carrying different combinations of Ppd-1a insensitivity alleles were tested under a wide range of photoperiods, including switches in photoperiod at the onset of stem elongation. Using multimodel inference we found that Ppd-1a alleles reduced photoperiod sensitivity of (i) emergence to anthesis and (ii) emergence to onset of stem elongation, both in a less than additive manner, while threshold photoperiod and intrinsic earliness were unaffected. Sensitivity to current photoperiod from onset of stem elongation to flag leaf and from then to anthesis was milder than for previous phases and was not related to variability in Ppd-1. However, ‘memory’ effects of previously experienced photoperiod on the duration from onset of stem elongation to flag leaf were related to variability in Ppd-1. The characterization and quantification provided here of the effects on development of Ppd-1 allelic combinations should help increase accuracy of genotype-to-phenotype models in predicting wheat phenology.EEA PergaminoFil: Perez Gianmarco, Thomas. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; Argentina. CONICET-UNNOBA.CITNOBA; ArgentinaFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; ArgentinaFil: González, Fernanda G. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; Argentina. CONICET-UNNOBA.CITNOBA; Argentin

Eficiencia de uso del agua de cultivares de soja desarrollados para La Pampa central Argentina: efectos del mejoramiento genético y del ambiente

En los próximos años se prevé un aumento importante en la demanda mundial de alimentos como producto de un incremento de la población. Para cubrir esa demanda, la producción deberá aumentar a casi el doble (Ray et al., 2013). Argentina es uno de los principales países productores y exportadores de soja Glycine max (L.) Merr.EEA PergaminoFil: Avalos Britez, S.R. Universidad de Buenos Aires. Facultad de la Agronomía (Becaria); ArgentinaFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; ArgentinaFil: Cirilo, Alfredo Gabriel. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; ArgentinaFil: Otegui, María Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; Argentin

Predicting soybean development with a simple photothermal dynamic algorithm

Predicting the occurrence of the critical period for soybean’s yield determination is important for farmers to decide on variety and sowing date with the objective to expose this period (during which yield is mainly determined) to the best environmental conditionsEEA PergaminoFil: Severini, Alan. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Sección Ecofisiología; ArgentinaFil: Álvarez Prado, S. Universidad de Buenos Aires, Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Otegui, María Elena. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Pergamino. Ecofisiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Vega, Claudia Rosa Cecilia. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Manfredi; ArgentinaFil: Zuil, Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Reconquista; ArgentinaFil: Kavanová, M. Instituto Nacional de Investigación Agropecuaria (INIA). La Estanzuela; UruguayFil: Ceretta, S. Instituto Nacional de Investigación Agropecuaria (INIA). La Estanzuela; UruguayFil: Acreche, Martin Moises. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Scholz Drodowski, R.F. Instituto Paraguayo de Tecnología Agraria (IPTA). Capitan Miranda; ParaguayFil: Serrago, R.A. Universidad de Buenos Aires, Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Miralles, D.J. Universidad de Buenos Aires, Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

CRONOSOJA: a daily time-step hierarchical model predicting soybean development across maturity groups in the Southern Cone

Accurate prediction of phenology is the most critical aspect for the development of models aimed at estimating seed yield, particularly in species that exhibit variable sensitivity to environmental factors throughout the cycle and among genotypes. With this purpose, we evaluated the phenology of 34 soybean varieties in feld experiments located in Argentina, Uruguay and Paraguay. Experiments covered a broad range of maturity group (MG)s (2.2–6.8), sowing dates (SDs) (from spring to summer) and latitude range (24.9–35.6 °S), thus ensuring a wide range of thermo-photoperiodic conditions during the growing season. Based on the observed data, daily time-step models were developed and tested, frst for each genotype, and then across MGs. We identifed base temperatures specifc for diferent developmental phases and an extra parameter for calculating the photoperiod efect afer the R1 stage (fowering). Also, an optimum photoperiod length for each MG was found. Model selection showed that the determinants of phenology across MGs were mainly afecting the duration of vegetative and early reproductive phases. Even so, early phases of development were beter predicted than later ones, particularly in locations with cool growing seasons, where the model tended to overestimate their duration. In summary, we have constructed a soybean phenology model that simulates phenology accurately across various geographic locations and sowing dates. The model’s process-based approach has resulted in root mean square errors ranging from 5.8 to 9.5 days for diferent developmental stages.Fil: Severini, Alan David. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Alvarez Prado, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario; ArgentinaFil: Otegui, Maria Elena. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Norte. Estación Experimental Agropecuaria Pergamino; ArgentinaFil: Kavanová, Monika. Instituto Nacional de Investigacion Agropecuaria;Fil: Vega, Claudia Rosa Cecilia. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Manfredi; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zuil, Sebastian. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Santa Fe. Estación Experimental Agropecuaria Rafaela; ArgentinaFil: Ceretta, Sergio. Estacion Experimental la Estanzuela ; Instituto Nacional de Investigacion Agropecuaria;Fil: Acreche, Martin Moises. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Salta-Jujuy. Estación Experimental Agropecuaria Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Amarilla, Fidencia. Instituto Paraguayo de Tecnología Agraria; ParaguayFil: Cicchino, Mariano Andrés. Instituto Nacional de Tecnologia Agropecuaria. Centro Regional Buenos Aires Sur. Estacion Experimental Agropecuaria Cuenca del Salado.; ArgentinaFil: Fernández Long, María Elena. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Crespo, Aníbal. Universidad de Buenos Aires. Facultad de Agronomía; ArgentinaFil: Serrago, Roman Augusto. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Miralles, Daniel Julio. Universidad de Buenos Aires. Facultad de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Measurement of the inclusive isolated-photon cross section in pp collisions at √s = 13 TeV using 36 fb−1 of ATLAS data

The differential cross section for isolated-photon production in pp collisions is measured at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 36.1 fb. The differential cross section is presented as a function of the photon transverse energy in different regions of photon pseudorapidity. The differential cross section as a function of the absolute value of the photon pseudorapidity is also presented in different regions of photon transverse energy. Next-to-leading-order QCD calculations from Jetphox and Sherpa as well as next-to-next-to-leading-order QCD calculations from Nnlojet are compared with the measurement, using several parameterisations of the proton parton distribution functions. The predictions provide a good description of the data within the experimental and theoretical uncertainties. [Figure not available: see fulltext.