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Odi-Lara M.,Colegio de Mexico | Paz-Pellat F.,Colegio de Mexico | Lopez-Urrea R.,Instituto Tecnico Agronomico Provincial | Gonzalez-Piqueras J.,University of Castilla - La Mancha

High density foliage crops produce the rapid saturation of the red band and reduction of variations in curve slopes of the same vegetation (iso-LAI), on which many vegetation indexes (VI) are based. For this reason, it is important to develop alternative indexes that do not become saturated and that are easily parameterized with information from the field. To this end, temporal patterns of spectral indexes (expo-linear model as reference) were evaluated based on the slopes of the iso-LAI lines, as well as the biophysical variables aerial biomass (Bm), aerial cover (fv) and height (h) of two crops with different foliage density: high (sorghum) and medium (cotton). When an expo-linear model is applied, it is expected that it would have a bi-linear pattern, as long as the variables coincide in their initial and end phases. In general, the Bm exponential and linear phases do not coincide with those of fv and h; this shows that there are differences among the structural characteristics, those of spatial vegetation distribution (fv and h), and photosynthetic function (foliage and biomass). The medium density crop exhibited well-characterized bilinear patterns. In contrast, the high density crop saturated rapidly in the exponential phase of Bm. To reduce the problem of saturation, the use of the additive constant a0 was explored as an alternative to the indexes based on slope. The relationship between the additive constant and Bm exhibited patterns of the double expo-linear type with problems in the definition of its transitions; the relationship with the variable fv were bi-linear, both for the medium density crop and for the high density crop, thus facilitating parameterization the vegetation indexes (use of fv) in the field; with height, the relationship was linear-exponential. Source

Noves B.,Instituto Tecnico Agronomico Provincial | Libran C.,University of Castilla - La Mancha | Licon C.C.,University of Castilla - La Mancha | Molina M.P.,Polytechnic University of Valencia | And 2 more authors.
CYTA - Journal of Food

Given their broad spectrum, cephalosporins are used for combating mastitis in dairy species. Many cephalosporins, such as cephalexin, have not been authorized for use in lactating sheep and because veterinary drugs for use in small species are lacking, the regulations of several countries allow extra-label use. Incorrect use of extra-label tools may cause residues in milk, and could negatively affect public health by provoking technological failures in the dairy fermenting processes. The effects of cephalexin, at concentrations close to its European Maximal Residue Limit (MRL), have been studied in set-type yogurts made from sheeps milk. Milk was fortified at different cephalexin concentrations and stored yogurts were evaluated in acidification, textural parameters and microbial evolution terms. The results showed that cephalexin concentrations equal to or below its MRL could mainly inhibit normal Streptococcus thermophilus growth and provoke some alterations to acidity parameters, which were more marked in the L(+)-lactic acid isomer. © 2014 Taylor & Francis. Source

Sadras V.O.,South Australian Research And Development Institute | Lawson C.,South Australian Research And Development Institute | Montoro A.,Instituto Tecnico Agronomico Provincial
Field Crops Research

We investigated crop and leaf photosynthetic traits in a set of Australian wheats released between 1958 and 2007. Environmental variation generated a range in pre-anthesis radiation use efficiency between 1.54 and 2.68gMJ -1. For these contrasting conditions, radiation use efficiency increased linearly with year of cultivar release at a rate of 0.012gMJ -1 per year. The fraction of incident radiation at different depths in the canopy profile increased linearly with year of cultivar release. Leaf greenness increased with year of cultivar release but the magnitude of this effect varied in the canopy profile; SPAD increased 0.24unitsyr -1 between 0 and 0.2m, 0.44unitsyr -1 between 0.2 and 0.3m, 0.22unitsyr -1 between 0.3 and flag leaf, and 0.11unitsyr -1 for the flag leaf. There was a sharp extinction of nitrogen concentration with canopy depth relative to the extinction of radiation in older varieties that shifted to a flatter nitrogen-radiation extinction in newer varieties. Increased radiation use efficiency in newer varieties was associated with the relaxation in the coupling between the extinction of nitrogen and radiation in the profile which was in turn partially related to the improved nitrogen status of modern varieties, as quantified with the nitrogen nutrition index. Stomata density (range: 38-56mm -2), stomata length (0.043-0.055μm), stomata width (0.024-0.032μm), light-saturated photosynthesis (9.3-19.6μmolm -2s -1) and respiration (1.6-7.3μmolm -2s -1) measured in the flag leaf at anthesis were unrelated to year of cultivar release. Shifts in crop-level traits associated with breeding and selection for yield were a likely source of improvement in pre-anthesis radiation use efficiency. © 2012 Elsevier B.V. Source

Sadras V.O.,South Australian Research And Development Institute | Montoro A.,Instituto Tecnico Agronomico Provincial | Moran M.A.,South Australian Research And Development Institute | Aphalo P.J.,University of Helsinki
Agricultural and Forest Meteorology

We measured the effect of elevated temperature, and its interaction with fruit load (exp. 1) and water supply (exp. 2), on the stomatal conductance (g s) of Vitis vinifera, cv. Shiraz. Thermal regimes (control vs. elevated temperature using open-top chambers) were initiated in spring, thus affecting leaf development, and were maintained during the whole growing season. We used a top-down approach where reaction norms were derived that relate g s for each treatment and the mean g s across treatments; the slopes of reaction norms quantify phenotypic plasticity.Stomatal conductance responded to neither the interaction between temperature and fruit load (P=0.37) nor the interaction between temperature and water regime (P=0.33). We therefore dealt with each factor separately. Reaction norms of g s under elevated temperature and control treatments diverged, i.e. elevated temperature had no effect on g s under conditions conducive to low conductance (below ∼100mmolm -2s -1) but increased g s in relation to controls under conditions favouring high conductance. Stomata density was 159±6.7mm -2, and was unaffected by temperature. Stomata length increased from 20.6μm in controls to 23.2μm in the heated treatment (P<0.0001) and width increased from 14.4μm in controls to 16.8μm in the heated treatment (P<0.0001). Thus, longer and wider stomata contributed to the enhanced plasticity of stomatal conductance under elevated temperature. Consistently, reaction norms of light-saturated photosynthesis were divergent, i.e. elevated temperature did not affect photosynthesis under conditions conducive to low g s and photosynthesis, but increased photosynthesis in relation to controls under more favourable conditions. A high source:sink ratio reduced the plasticity of stomatal conductance. Water regime had a minor effect on the plasticity of stomatal conductance, but the reaction norms for irrigated and water deficit treatments were offset by ∼60mmolm -2s -1 thus indicating a consistent effect of water deficit across environmental conditions.We conclude that the responses of stomata derived from transient temperature treatments in fully expanded leaves are unsuitable to model the dynamics of gas exchange in response to projected warming. Our experiments support a conceptual model where current stomatal conductance is a function of (i) the prevailing environmental conditions during early stages of leaf development that set the upper limit of conductance through the modulation of stomatal density and size, (ii) the current environmental conditions and (iii) the source:sink ratio. © 2012 Elsevier B.V.. Source

Lopez-Urrea R.,Instituto Tecnico Agronomico Provincial | Montoro A.,Instituto Tecnico Agronomico Provincial | Manas F.,Instituto Tecnico Agronomico Provincial | Lopez-Fuster P.,Instituto Tecnico Agronomico Provincial | Fereres E.,University of Cordoba, Spain
Acta Horticulturae

The aim of this study was to quantify the water use of mature grapevines (Vitis vinifera 'Tempranillo'), under full water supply, during two growing seasons. The experimental work was carried out in the lysimeter facilities located in Albacete (central Spain), under semi-arid climate conditions. In 1999, a weighing lysimeter was installed in the centre of a plot (100×100 m). A monolith of undisturbed soil was placed inside the lysimeter tank which was 3×3 m and 1.7 m deep. The overall resolution of the weighing system was 250 g. Two vines under drip irrigation were planted in the lysimeter, each one occupying 4.5 m2, the same as the vines in the rest of the plot. The lysimeter's daily mass change was used to determine grapevines water use. To schedule irrigation, ETc values were calculated from daily mass loss minus drainage loss, and water was applied to replace the loss, thus, maintaining non-limiting soil water content. Seasonal grapevine ET measured in the lysimeter differed between the two years: it was 377 mm in 2008 and increased to 505 mm in 2009. The lower ETc values in 2008 were directly related to a smaller canopy that year. Canopy cover due to pruning differences was about 15% higher in 2009 than in 2008. Such differences also affected the peak crop coefficient (Kc) values. Peak Kc in 2008 was 0.51 while it reached 0.72 in 2009. In both cases the peak values were achieved in the period between veraison and harvest. Source

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