Dry Matter Dynamics Research Articles

Preliminary Study on Effect of Early Defoliation on Dry Matter Accumulation and Storage of Reserves on ‘Abbé Fétel’ Pear Trees

Annual accumulation of starch is affected by carbon reserves stored in the organs during the growing season and is controlled mainly by sink strength gradients within the tree. However, unfavorable environmental conditions (e.g., hail events) or application of management practices (e.g., defoliation to enhance overcolor in bicolor apple) could influence the allocation of storage carbohydrates. This preliminary research was conducted to determine the effects of early defoliation on the dry matter, starch, and soluble carbohydrate dynamics in woody organs, roots, and mixed buds classified by age and two levels of crop-load for one growing season in ‘Abbé Fétel’ pear trees (Oct. 2012 to mid-Jan. 2013 in the northern hemisphere). Regardless of the organs evaluated (woody organs, roots, and mixed buds), an increase of soluble carbohydrate concentration was observed in these organs in the period between after harvest (October) and January (dormancy period). Among all organs, woody short-old spurs showed the highest increase (+93.5%) in soluble sugars. With respect to starch, woody organs showed a clear trend of decreasing in concentration between October and January. In this case, short-old spurs showed the smallest decline in starch concentrations, only 6.5%, whereas in other tree organs starch decreased by 34.5%. After harvest (October), leaves showed substantially higher starch and soluble sugar concentrations in trees with lower crop-loads. These results confirm that in the period between October and January, dynamic interconversions between starch and soluble carbohydrates occur at varying magnitudes among organs in pear trees.

Simulation of Phosphorus Chemistry, Uptake and Utilisation by Winter Wheat.

The phosphorus (P) supply from soils is crucial to crop production. Given the complexity involved in P-cycling, a model that can simulate the major P-cycling processes and link with other nutrients and environmental factors, e.g., soil temperature and moisture, would be a useful tool. The aim of this study was to describe a process-based P module added to the SPACSYS (Soil Plant and Atmosphere Continuum System) model and to evaluate its predictive capability on the dynamics of P content in crops and the impact of soil P status on crop growth. A P-cycling module was developed and linked to other modules included in the SPACSYS model. We used a winter wheat (Triticum aestivum, cv Xi-19) field experiment at Rothamsted Research in Harpenden to calibrate and validate the model. Model performance statistics show that the model simulated aboveground dry matter, P accumulation and soil moisture dynamics reasonably well. Simulated dynamics of soil nitrate and ammonium were close to the observed data when P fertiliser was applied. However, there are large discrepancies in fields without P fertiliser. This study demonstrated that the SPACSYS model was able to investigate the interactions between carbon, nitrogen, P and water in a single process-based model after the tested P module was implemented.

Modeling wheat nutritional quality with a modified CERES-wheat model

Abstract Grain protein concentration (GPC), lysine, and essential amino acid (EAA) are key components of the nutritional quality of wheat. Quantitative analysis and numerical simulation of wheat nutritional quality based on the new findings in this study were used to extend the functionality of the CERES-Wheat model. The main assumptions in this model are as follows. (1) The minimum value of nitrogen stress and water stress, had a significant linear correlation with nitrogen-to-protein conversion factor (Fp). (2) An alteration in GPC, whether its cause is genetic or not, results in the same modifications in grain amino acid composition. (3) Amino acid compositions were precisely simulated by Fp and GPC. An appended module of nutritional quality was combined with a revised version of the CERES-Wheat model, enabling us to simulate wheat nutritional quality. The modified CERES-Wheat model could accurately simulate dry matter and nitrogen dynamics. The percent deviation differences between the simulated and observed average values of 16 treatments were all less than 10%. The RRMSE of GPC, EAA, and lysine were all less than 0.1. The nutritional quality module based on CERES-Wheat could accurately simulate GPC, lysine, and EAA. The simulated yield results were underestimated with severe nitrogen stress, while GPC, lysine, and EAA were overestimated with slight nitrogen stress. The nutritional quality module provides a simple mechanistic framework that explains environmental effects on GPC, EAA, and lysine.

Importance of whole plant dry matter dynamics for potato (Solanum tuberosum L.) tuber yield response to an episode of high temperature

Potato is adapted to mild climates, but climate change may increase its exposure to more high temperature episodes of greater severity. However, there is limited information on the likely response of potato to high temperature episodes. We investigated the growth of potato exposed to an episode of high temperature before (Expt. 1) or after tuber initiation (Expt. 2). In both glasshouse experiments, plants were grown at 22 °C. At 35 days after planting (DAP) (Expt. 1) or 43 DAP (Expt. 2), plants were transferred to high temperature treatments of 26 or 30 °C for nine days then returned to 22 °C for 26 days. Tuber dry matter was reduced to a similar extent whether the high temperature episode occurred before or after tuber initiation. These effects were inconsistent with previously proposed mechanisms that attributed reduced tuber dry matter to starch synthase inhibition or increased gibberellic acid production. They were more consistent with insufficient whole plant carbon occasioned by reduced leaf area and continued shoot growth, particularly of the laterals, during and after the high temperature episode. Starch and sucrose distribution in the plants supported this but also suggested different mechanisms when the high temperature occurred before or after tuber initiation.

Dynamics of dry matter and nitrogen distribution in transplanted rice on mollisols

We studied the dynamics of dry matter (DM) and nitrogen (N) distribution in different plant parts (leaf, stem, and panicle) and grain yield of transplanted rice due to N management practices through neem coated urea (NCU). The results indicated that application of NCU at 125% recommended dose of N (RDN) with 50:25:25 split schedule at basal (B), active tillering (AT), and panicle initiation (PI) stages resulted in higher DM and N distribution to leaf, stem, and panicle at 60 and 90 days after transplanting and harvest than the application of prilled urea at 100% RDN with the same split schedule (existing practice). Further, the increment in grain yield was 10.95% than the existing practice. Hence, we suggest the application of NCU at 125% RDN with 50:25:25 split schedule at B, AT, and PI stages for achieving higher DM and grain yield on Mollisols.

Yield and dry matter dynamics of vegetative and reproductive organs in Japanese and US soybean cultivars

ABSTRACTRecently, US soybean cultivars have exhibited higher yields than Japanese soybean cultivars. To identify the determinants for this yield difference in reference to dry matter dynamics, recently developed US cultivars and Japanese commercial cultivars were cultivated in drained paddy fields in 2012 and 2013. The total dry matter (TDM) of each cultivar was measured at the initial seed-filling stage (R5), at 30 d after R5, and at maturity (R8). From R5 to R8, the DM of abscised leaves and petioles were measured. The actual HI (with abscised leaves and petioles) and apparent HI (without abscised leaves and petioles) were determined at R8. US soybean cultivars showed higher yields and apparent TDM (without abscised leaves and petioles) than did Japanese cultivars at R8. However, the difference in actual TDM (with abscised leaves and petioles) production was not significant between US and Japanese cultivars at R8. On the other hand, the actual HI was higher in US cultivars than in Japanese cultivars. US cultivars exhibited a higher TDM distribution to the pod before R5 and a higher pod growth rate from R5 to 30 d after R5. US cultivars tended to show greater crop growth rates (CGRs) from R5 to 30 d after R5. The higher yield in US cultivars was associated with the higher actual HI, which was considered attributable to a greater TDM productivity during the seed-filling period and higher DM distribution in the pod before R5.

How does STICS crop model simulate crop growth and productivity under shade conditions?

Most crop models have been developed with crops growing under full sunlight conditions and they commonly use daily cumulated global radiation as part of the climatic input data. This approach neglects the spatio-temporal dimension of the light reduction experienced by the crop in agroforestry systems. In this study, we evaluate the ability of the crop model STICS to predict winter wheat (Triticum aestivum L.) growth and yield under three distinct light conditions using field observations from a two year artificial shade experiment. The shade structure induced a continuous shade (CS) treatment characterized by a reduction of the proportion of light during the entire day and a periodic shade (PS) treatment defined by an intermittent shade varying on the plot throughout the day. These two shade conditions were compared to a no shade treatment (NS) receiving 100% of the available light. The model accurately predicted the timing of the grain maturity stage under the PS treatment by reducing the daily global radiation only. A correct prediction of this growth stage in the CS treatment required a decrease of the daily maximum air temperature in addition to the reduction of global radiation. Overall, the model accurately reproduces the total aboveground dry matter dynamics under the CS and NS treatments, but did not simulate the reduction observed under the PS treatment correctly. Three parameters (nbjgrain, cgrain and cgrainvo) involved in the determination of the number of grains have been calibrated with the NS treatment data and were then used to predict the crop behavior under the shaded treatments. Using this adjusted parameter set, the STICS model gave a good prediction of the grain number under all treatments. Nevertheless, the simulation of final grain yield under the shade treatments was not satisfactory yet, presumably due to an overestimation of the reallocation of the biomass between shoots and grains. Improving the prediction of these reallocation processes is challenging and critical to improve the simulation of crop behavior under fluctuating light environments such as encountered in agroforestry systems.

Compliant contact versus rigid contact: A comparison in the context of granular dynamics.

We summarize and numerically compare two approaches for modeling and simulating the dynamics of dry granular matter. The first one, the discrete-element method via penalty (DEM-P), is commonly used in the soft matter physics and geomechanics communities; it can be traced back to the work of Cundall and Strack [P.Cundall, Proc. Symp. ISRM, Nancy, France 1, 129 (1971); P. Cundall and O. Strack, Geotechnique 29, 47 (1979)GTNQA80016-850510.1680/geot.1979.29.1.47]. The second approach, the discrete-element method via complementarity (DEM-C), considers the grains perfectly rigid and enforces nonpenetration via complementarity conditions; it is commonly used in robotics and computer graphics applications and had two strong promoters in Moreau and Jean [J. J. Moreau, in Nonsmooth Mechanics and Applications, edited by J. J. Moreau and P. D. Panagiotopoulos (Springer, Berlin, 1988), pp. 1-82; J. J. Moreau and M. Jean, Proceedings of the Third Biennial Joint Conference on Engineering Systems and Analysis, Montpellier, France, 1996, pp.201-208]. The DEM-P and DEM-C are manifestly unlike each other: They use different (i) approaches to model the frictional contact problem, (ii) sets of model parameters to capture the physics of interest, and (iii) classes of numerical methods to solve the differential equations that govern the dynamics of the granular material. Herein, we report numerical results for five experiments: shock wave propagation, cone penetration, direct shear, triaxial loading, and hopper flow, which we use to compare the DEM-P and DEM-C solutions. This exercise helps us reach two conclusions. First, both the DEM-P and DEM-C are predictive, i.e., they predict well the macroscale emergent behavior by capturing the dynamics at the microscale. Second, there are classes of problems for which one of the methods has an advantage. Unlike the DEM-P, the DEM-C cannot capture shock-wave propagation through granular media. However, the DEM-C is proficient at handling arbitrary grain geometries and solves, at large integration step sizes, smaller problems, i.e., containing thousands of elements, very effectively. The DEM-P vs DEM-C comparison is carried out using a public-domain, open-source software package; the models used are available online.

A long-term data sequence (1960-2013) to analyse the sustainability of hay quality in irrigated permanent grassland under climate change

Face to climate, land and water use changes, sustainability of crop systems and quality of production is in debate. Long term database concerning hay's mineral contents, dry matter and climate dynamics (rainfall and temperature) have been collected and are used here to argue these questions. Such data are scarce, but here were made available, as they were used to obtain and maintain the certification of the crop, specifically Certified Origin Product (COP) hay. Database collected cover 1960-2013 period, in Crau area, South-Eastern France. Permanent grasslands have been established in this plain since the XVIth century and depend on border irrigation. Statistical tests show that a steady state of the total mineral content and dry matter within long-term has been reached. There is no significant correlation between rainfall and mineral content in hay. Additionally, there is no impact of temperature change on dry matter. Furthermore, the total mineral content of hay is systematically the largest in the third cut and the smallest in the first cut. Our findings suggest that irrigation plays a key role for grasslands sustainability. Irrigated grasslands in Crau area appear as a model of intensive agroecology, with COP productions of high value (hay and animal productions), a crop system, created in the XVIth century and that demonstrates its resilience face to the present global changes. It is however presently jeopardized by urban sprawl.

Dynamics of dry matter and selenium accumulation in oilseed rape (Brassica napus L.) in response to organic and inorganic selenium treatments

The uptake by and subsequent translocation of selenium (Se) within the plant is dependent on its chemical from and soil properties that dictate this trace element’s bioavailability. Plant species differ in their tendency to accumulate Se. Se taken-up by plants is returned to soil in plant residues, but the bioavailability of organic Se in those residues is poorly known. We investigated the impact of inorganic (Na2SeO4), organic (Se-enriched stem and leaf residues) Se applications and also soil microbial respiration on the growth and Se concentrations of various plant organs of oilseed rape (Brassica napus L.) during its development from the rosette to the seed filling stage. Both inorganic and organic Se slightly improved plant growth and enhanced plant development. Inorganic Se was more bioavailable than the organic forms and resulted in 3-fold to 6-fold higher Se concentrations in the siliques. Inorganic Se in autoclaved soil tended to elevate the Se concentration in all plant parts and at all growth stages. The organic Se raised Se concentrations in plants much less effectively than the inorganic selenate. Therefore, the use of inorganic Se is still recommended for biofortification.

Dry matter and water dynamics of wheat grains in response to source reduction at different phases of grain filling

Agreement that wheat (Triticum aestivum L.) is scarcely limited by source of assimilates during grain fill has not been confirmed when source was drastically decrease in high yield potential environments. Dry matter (DM) and water dynamics of growing grains being possibly able to explain grain weight (GW) responses to source-sink ratios (S-Sratios) in these conditions. Objectives were to evaluate response of GW to S-Sratios at different phases during grain fill, and relationship between DM and grain water content in response to different S-Sratios. Wheat was sown at field conditions during 20042005 and 2005-2006 growing seasons. Four S-Sratios were assessed: Control without S-Sratios modification (C), S-Sratios from anthesis (At) +12 d to physiological maturity (ShAll), S-Sratios from At +12 d to first half of grain fill (Sh1st) and from second half of grain fill to maturity (Sh2nd). Thousand grain weight (TGW), GW at individual positions (IGW), stabilized grain water content (SGWC) and grain filling rate (GFR) were measured. TGW sensitivity to S-Sratios varied according to length of treatment and its timing, i.e. ShAll, Sh1st, and Sh2nd treatments reduced TGW by 48%, 26%, and 22%, respectively. These reductions were little higher when IGW were evaluated in ShAll (i.e. 53%) and Sh1st (i.e. 33%) treatments and lower in Sh2nd (i.e. 12%). SGWC sensitivity was lower than that of IGW across S-Sratios (e.g. SIiau 27%, Shust 22%, and Sh2nd 5%). However, close association between IGW and SGWC (R2 = 0.78, p < 0.001) and between GFR and SGWC (R2 = 0.98, p ≤ 0.001) was found regardless of S-Sratios and seasons

Comparative behavior of wheat and barley associated with field release and grain weight determination

Double-cropping using the wheat–soybean sequence is a common practice in Argentina to promote the intensification of crops within rotations. However, the late release of the fields by a delayed harvest time in wheat determines soybean yield penalizations. In this context, barley could represent a better option than wheat preceding soybean in the crop rotation since there is some evidence that finishes its cycle earlier than wheat. However, it is not clear which period of barley shortens crop cycle allowing an earlier field release than wheat. The objectives of this study were to compare wheat and barley in terms of (i) field release and (ii) grain weight determination through the analysis of their physiological mechanisms. Field experiments during two consecutive growing seasons testing five different environments (three sowing dates in 2007 and two in 2008) were carried out to analyze the duration of different ontogenic periods and the attributes (dry matter and water dynamics) determining grain weight during the grain-filling period in wheat and barley. Early flowering time was the main cause of the early field release by barley as the grain filling and drying period were similar in both species. A strong relationship was found between dry matter and water dynamics in both species. Barley reached a higher maximum water content than wheat and also achieved physiological maturity with higher moisture concentration than wheat (48% and 39%, respectively). Barley showed a slight increase in grain weight, respect to wheat, due to a source:sink ratio enhancement (4% and 9% for wheat and barley, respectively). These data show an opposite response to that of Mediterranean, Australian and UK environments, where barley was under stronger sink limitation than wheat during the grain-filling period.

Matter dynamics with respect to influences of C3and C4plants in four subtropical grasslands of Nilgiri Biosphere Reserve, the Western Ghats, India

Biomass changes, net primary production and transfer dynamics of dry matter in four subtropical humid montane grasslands at Ebbenadu, Korakundah, Thiashola and Wenlockdown in Nilgiri Biosphere Reserve (NBR), the Western Ghats, India, were investigated. Despite the early report of a higher density and dominance of <TEX>$C_4$</TEX> species over <TEX>$C_3$</TEX> species in these grasslands, no functional study of matter production had previously been carried out. Therefore, in order to determine the roles played by these two groups of species, the present study was attempted. The study revealed that the dry matter and net primary production contributed by <TEX>$C_4$</TEX> species were much greater than those of its <TEX>$C_3$</TEX> counterpart in all the grasslands. The turnover rate of aboveground dry matter for both <TEX>$C_3$</TEX> and <TEX>$C_4$</TEX> species was generally rapid, whereas it was slow for belowground parts, and litter components of <TEX>$C_3$</TEX> and <TEX>$C_4$</TEX> species together. In all grasslands, generally about 60% and 10% of the input were channeled to aboveground and belowground parts, respectively, by the <TEX>$C_4$</TEX> species, whereas the <TEX>$C_3$</TEX> species transferred only about 22% and 8% of dry matter to aboveground and belowground parts, respectively. The total disappearance of dry matter was 2.73, 2.10, 3.19, and <TEX>$1.96\;g\;m^{-2}\;day^{-1}$</TEX> in Ebbenadu, Korakundah, Thiashola and Wenlockdown grasslands, which was 48.83%, 44.30%, 54.81%, and 41.09% of the total input, respectively, in these grasslands. This resulted in a considerable surplus dry matter production in all the grasslands studied. This balance sheet of dry matter in community function indicates that all the four studied grasslands were supporting the existing wild animals adequately in terms of pasture supply. The study further revealed that the stronger establishment of <TEX>$C_4$</TEX> species rather than their <TEX>$C_3$</TEX> counterparts, in terms of higher density and dominance, has driven them to play major roles in matter dynamics and system transfer functions in all the four grasslands studied. This fact evidenced that pasture from <TEX>$C_4$</TEX> species for wild animals was determined to be higher in comparison to that of <TEX>$C_3$</TEX> species.

Nitrogen and dry matter dynamics in linseed as affected by the nitrogen level and genotype in a Mediterranean environment

Abstract Linseed or oilseed flax ( Linum usitatissimum L.) is an important source of edible and industrial vegetable oil and is grown widely in temperate regions around the world. Nitrogen, one of the most important nutrients for linseed, is often applied for higher yield and better quality. However, the effects of N level on dry matter and N accumulation, partitioning, and retranslocation have not yet been identified in linseed. A two-year field study was therefore conducted to determine the effects of N level on dry matter, N accumulation, partitioning, and retranslocation of three linseed cultivars (Livia, Lirina, Creola) grown in a Mediterranean environment under rain-fed conditions. It was found that N fertilization increased biomass at anthesis by an average of 47% and at maturity by an average of 38%, compared with the control. N fertilization increased the dry matter partitioning in leaves + flowers and stems at anthesis, and also in leaves + capsule vegetative components, stems, and seeds at maturity. Dry matter translocation was affected by N fertilization, growing season, and by the interaction between growing season and N treatment. In addition, N fertilization increased N retranslocation from the vegetative parts of the plant to the seed. Moreover, the N uptake by seeds was more affected by the seed yield and less affected by the seed N concentration. The present study indicates that N fertilization affects dry matter and N translocation in linseed.

Carpel weight, grain length and stabilized grain water content are physiological drivers of grain weight determination of wheat

Among the yield components, grain weight is considered a conservative trait whose determination is still beyond our complete understanding. Crop physiology uses a whole approach to study this complex trait, which can provide helpful information to plant breeders and molecular biologists. This study emphasizes the understanding of pre- and post-anthesis determinants of final grain weight. A field experiment was carried out in two growing seasons evaluating two wheat cultivars contrasting in grain weight potential. Carpel weight at pollination, grain dimensions, grain water, dry matter and volume dynamics were assessed. Among grain dimensions, grain length was the trait, which explained final grain weight ( r 2 = 0.78; P < 0.01 and r 2 = 0.94; P < 0.001 for the 1st and 2nd season, respectively) and it was the first trait to stabilize after anthesis. Water content of grains stabilized little later and also showed a strong association with final grain weight ( r 2 = 0.93; P < 0.01 and r 2 = 0.98; P < 0.01 for the 1st and 2nd season respectively). Most importantly, carpel weight at pollination showed a positive and linear association with final grain weight ( r 2 = 0.79, P < 0.01 and r 2 = 0.86 P < 0.01 for the 1st and 2nd season, respectively) irrespective of the cultivar and grain position. In addition, positive associations were also found between grain volume, water content, grain length, and carpel weight at pollination. Therefore, the associations between pre- and post-anthesis traits found in this study support the hypothesis that grain weight is determined before anthesis and fruit tissues (i.e., pericarp in cereals and sunflower) set an upper limit to grain weight.

Post-anthesis dry matter and nitrogen dynamics in durum wheat as affected by nitrogen and temperature during grain filling

Durum wheat (Triticum turgidum L. var. durum Desf.) is commonly grown in Mediterranean conditions, where temperature stress during grain filling can limit productivity. This research was performed to evaluate the effect of temperature during grain filling on dry matter and nitrogen dynamics in two Italian durum wheat varieties, Appio and Creso, grown with different nitrogen availabilities. The experiment compared two different temperature regimens, one within the normal range occurring during grain filling in Central Italy, the other within the normal range occurring in the southern regions of Italy (20/15 °C and 28/23 °C day/night, respectively). Plants were grown in pots outdoor until anthesis and afterward were placed in growth chambers. Results showed that nitrogen fertilization and post-anthesis temperature affected growth, accumulation and partitioning of dry matter and N in durum wheat which, in turn, modified grain yield and N content. Grain yield was better expressed at 20/15 °C, while grain protein concentration was favoured under the 28/23 °C temperature regime. Higher temperature promoted remobilization of dry matter and restrained current photosynthesis, but reduced grain yield, indicating that the loss of photosynthesis could not compensate for the gain from increased remobilization. Grain N content, on the contrary, was promoted under the higher temperature regime, as high temperature reduced N remobilization but did not inhibit root water and nitrogen uptake, given that no water shortage occur.

Sowing date and nitrogen fertilisation effects on dry matter and nitrogen dynamics for durum wheat: An experimental and simulation study

The effects of sowing date and nitrogen (N) fertilisation on the dynamics of dry matter (DM) and N accumulation during grain filling and on final grain yield and protein concentration for durum wheat were studied in two field experiments. In addition, the ability of the wheat simulation model SiriusQuality1 to simulate grain yield and protein concentration for durum wheat was evaluated. The model simulated the anthesis date and the grain filling duration with a root mean square error of 1.7 and 2.2 days, respectively. The model simulated reasonably well the changes in the dynamics of leaf, stem and grain DM and N in response to sowing date and N fertilisation. Harvest grain yield and protein concentration were simulated with a root mean square error of 0.045 kg DM m −2 and 1.25%, respectively. The longer vegetative period with autumn sowing compared with winter sowing resulted in higher crop DM and N at anthesis, which was associated with higher final grain yield. Independently of the sowing date or N fertilisation, post-anthesis DM accumulation contributed 70% to final grain yield. Post-anthesis N accumulation contributed between 25% and 40% to final grain N yield depending on the sowing date and N fertilisation. The efficiency of vegetative DM and N remobilisation was not modified by the sowing date or N fertilisation, averaging 21% and 74%, respectively. Sowing date had larger effects on grain DM yield than on grain N yield and grain protein concentration was significantly higher for the late sowing date than for the normal sowing date. N treatments did not affect crop phenology, but N fertilisation allowed the crops accumulating more DM and N during the vegetative period. In addition, high-N crops, because of their larger canopy, accumulated more DM and N during grain filling than low-N crops, resulting in higher grain yield and protein concentration at harvest. Both grain number per unit ground area and grain yield were closely correlated with crop DM and N at anthesis. Single grain DM was not modified by N availability. Averaged across N treatments, single grain DM varied from 44.2 to 57.3 mg DM grain −1. These variations were almost entirely accounted for by the mean daily maximum temperature calculated for the 15 days prior to anthesis, suggesting that the temperature during the period of active cell division in the ovary is a major determinant of the final size of durum wheat grains.

Integrated Warm‐ and Cool‐Season Grass and Legume Pastures: I. Seasonal Forage Dynamics

High temperatures and scarce precipitation often cause the productivity and quality of cool‐season pastures in Southwest Michigan to decline for an extended period during the summer. This study was conducted to determine whether integration of switchgrass (Panicum virgatum L.) or big bluestem (Andropogon gerardii Vitm.) into cool‐season grazing systems would mitigate this period of low pasture productivity and quality. Cool‐season grass and legume pastures (CS‐Only) were compared to integrated big bluestem and cool‐season grass and legume pastures (CS‐BBS) and integrated switchgrass and cool‐season grass and legume pastures (CS‐SG). The seasonal dynamics of forage dry matter offered, crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were used to compare the dynamics of the pasture productivity and quality in each of three treatments. Dry matter offered in the CS‐Only treatment was higher earlier in the grazing season and the peak in dry matter‐offered occurred between 20 and 30 d earlier in the CS‐Only treatment than in the other treatments. The seasonal trend for CP was generally higher and more constant for the CS‐Only treatment than for the CS‐BBS and CS‐SG treatments, which were very similar to each other. The seasonal trend for ADF and NDF was generally lower and more constant for the CS‐Only treatment than for the CS‐BBS and CS‐SG treatments, which were very similar to each other. These findings suggest that, compared to the CS‐Only treatment, the CS‐SG or the CS‐BBS treatments probably will not improve livestock gain or improve the distribution of animal grazing days throughout the summer.

Asynchronous dynamics of grapevine ("Vitis vinifera") maturation: experimental study for a modelling approach

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aims&lt;/strong&gt;: An analysis of the asynchrony and dynamics of dry matter accumulation and water content in the grape berries growth period (Vitis vinifera L.) was carried out on a macroscopic scale (berry population). Experimental studies suggest a framework to evaluate the asynchronous nature of grapevine maturation and to propose a simple model to simulate dry matter and water dynamics.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;:Amethodology based on the measurement of the density of the berries was used, providing information on the dry matter, water content and distribution of the berry populations during the veraison - harvest period. The main experiment was carried out in Rhone valley vineyards on the«Grenache N » and « Syrah » varieties. Additional information was gathered in Burgundy vineyards on « Pinot noir » and « Chardonnay » varieties. A relationship between the sugar content (°Brix) and water content of a berry was observed, which was robust and identical for all varieties. The asynchronous nature of berry growth was confirmed and densimetry allows quantifying the homogeneity of harvest. A model was proposed to modelling dry matter growth, based on thermal time and final potential dry weight. A single relationship was obtained for the two varieties studied which seemed to be independent of field conditions (soil and year). To model water content dynamics (or °Brix, using the relationship obtained between them), two components were defined, one of which is related to the berry phenological stage and the other depends on the water status of the plant.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Conclusion&lt;/strong&gt;: The results provide a conceptual framework to better understand and represent the dynamics of dry matter accumulation and water content of a population of grape berries, and to evaluate the asynchronous nature of grapevine maturity.&lt;/p&gt;&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;: The models and relationships proposed could be used as a tool to better identify and understand key factors and processes occurring in the field until the detailed processes of berry growth are better understood and can be incorporated into the model. This model could be incorporated into a crop model of vine growth.&lt;/p&gt;

“In vivo” and “in vitro” degradability of diets for Parmigiano Reggiano cheese production

In vitro” Dry Matter (IVDMD) and fiber degradability (IVNDFD) dynamics were determined for Total Mixed Rations (TMR) typical of Parmigiano Reggiano cheese area. The same parameters were estimated on some of these ration also “in vivo” on a group of fresh cows. “In vivo” trial showed values of 62.21 and 44.82% for DMD and NDFD respectively, while average IVDMD was 67.48 and 74.33% at 24 and 48 hours respectively. At the same intervals IVNDFD was of 49.32 and 62.61%, indicating an high fiber digestibility of fresh cow. Based on the “in vitro” equations and the “in vivo” values, the ruminal retention time was estimated to be of about 21 hours for DMD and of 19 hours for NDFD.