Glass foam granulate as growing medium for tomato and cucumber

Glass foam granulate was evaluated for use as a horticultural rooting medium with laboratory tests and cultivation experiments. The laboratory tests included moisture characteristics, rehydration rate and pH buffering analyses. Cucumbers and later on tomatoes were propagated in rockwool propagation cubes and planted on slabs of Growstones™ glass foam granulate. They were compared with cucumber respectively tomatoes grown on rockwool slabs. Lab results show that the coarse nature of the glass foam granulate (0.5-5 cm) limits the maximum moisture content to 50%. The rehydration rate is very high, reaching more than 80% of container capacity in 5 min. The tested material initially reacts with water, raising the pH to over 10 pH units. Based on lab results a recipe for rinsing the material prior to cultivation was calculated. Cucumber cultivation results show an equal production to plants grown on rockwool. The first yield on glass foam granulate is 1-2 days earlier. The susceptibility to Pythium is significantly lower than on rockwool. The wax layer on cucumbers grown on glass foam granulate is perceptibly thicker as consequence of an elevated silicon level of 0.25 to 1.6 mmol L-1 in the slab solution. Tomatoes on glass foam granulate show smaller stem diameters and recovered faster from blossom end rot. Yield levels on glass foam granulate and rockwool are equal. In conclusion growing on glass foam granulate is equally productive as rockwool growing. The material is drier and thus less susceptible to Pythium and more generative in nature. Glass foam granulate can be irrigated with small and frequent irrigation cycles and the material must be rinsed with an acid solution before planting. Small amounts of silicon are released into the nutrient solution

Moonlight Down In Dixie

https://digitalcommons.library.umaine.edu/mmb-vp/3291/thumbnail.jp

Influence of water stress on grapevines growing in the field : from leaf to whole-plant response

International audienceA comparative study of soil-plant water relations was conducted on three grapevine cultivars (Vitis vinifera L. cvv. carignane, merlot, shiraz) to investigate their adjustment to short-term and long-term water stress under field conditions. Adjustment was a function of the relative stability of the internal plant water status on diurnal and seasonal scales. On a diurnal scale, stomatal closure in response to water vapour pressure directly contributed to this stability. Indirect evidence suggested an influence of the soil water status on the diurnal stomatal activity. On a seasonal scale, sufficient leaf hydration required high whole-plant hydraulic conductance. This was achieved by either daily stomatal regulation or limitation of leaf area. Physiological adjustment to water stress through stomatal control was well developed in cv. carignane, which originated in a Mediterranean environment. However, cv. shiraz, which was of mesic origin, apparently adjusted to water stress by reducing leaf area. Our study demonstrates the utility of integrating data on stomatal conductance, leaf water potential and whole-plant hydraulic conductance to interpret whole plant adaptation to water stress, and elucidates two mechanisms by which genotypes differentially acclimate to water stress

Stomatal conductance of some grapevines growing in the field under a mediterranean environment

International audienceA semi-empirical model of stomatal conductance was used to analyse porometer measurements on different grapevine cultivars under field conditions. Stomatal conductance was expressed as a function of quantum flux density, water vapour deficit, air temperature and leaf water potential. Where possible, the parameters describing the partial functions were estimated from field data and provide physiological insights into the transpiration process. They indicated differential stomatal sensitivity to air humidity in the various cultivars, a characteristic which could be related to their geographical origins

The Song That I Hear In My Dreams

https://digitalcommons.library.umaine.edu/mmb-vp/5336/thumbnail.jp

Identifying spatial patterns of Mediterranean landscapes from geostatistic analysis of remotely-sensed data

The basic tool of geostatistics, the semi-variograms, has been used for quantifying spatial structures of soil and vegetation, as depicted by multi-resolution remotely-sensed images. Experimental semi-variograms of two contrasting Mediterranean landscapes were analysed by reference to simple theoretical models (spherical, exponential, allometric). A more general approach based on the superposition of spherical models of similar sills and varying ranges of influences is proposed for the interpretation of complex spatial patterns of natural vegetated landscapes. (Résumé d'auteur

Testing an area-weighted model for albedo or surface temperature of mixed pixels in mediterranean woodlands

International audienceWe have tested the following assumption for a spatially complex area of natural vegetation in Southern France. The spectral response of a mixed pixel is a linear combination of the individual responses of its components. The test has been done with HCMM data: each pixel (500m spatial resolution) has been characterized by its components defined as physiognomical vegetation units. Results from the analysis of multitemporal HCMM data indicate that the assumption is verified for albedos and surface temperatures

Spatial variation and temporal persistence of grapevine response to a soil texture gradient

Studying the water transport in the soil-plant system requires information on the spatio-temporal variability of both subsystems and the ability to assess the impact of the soil heterogeneity and of the biological responses on the coupling between vegetation and its substrate. This study was conducted for 2 years in a vineyard in the Aude Valley, France, by measuring the particle size distribution of the topsoil, the instantaneous isotopic ratios (18O/16O, 2H/1H) of leaf water, annual shoot biomass production, and interannual persistence of this biomass along a 360 m transect. The resultant spatial series were analysed for their correlations and converted to spectra. Changes in the isotopic ratios along the transect reflect the soil texture gradient, suggesting that the vines root deeper on the gravel layers than elsewhere. This could provide a mechanism for the partial decoupling between soil and vegetation, and thus explain the strong temporal persistence of the vegetation pattern, the low overall correlation between biomass production and soil texture. The spectra show that this correlation concentrates at specific scales which correspond to a minimum variability in the shoot biomass. In this case, therefore, soil texture plays only a minor role in determining the spatial heterogeneity of shoot biomass in gravepine. (Résumé d'auteur

Verkenning van milieuemissies en verbruiken van schaarse hulpbronnen in de sectoren: konijnen, vleeskalveren, eenden en kalkoenen = Exploring environmental emissions and depletion of resources of rabbit, veal calf, duck, and turkey production chains in The Netherlands

For new design concepts of rabbit, veal calf, duck and turkey production systems insight is needed in environmental emissions and the use of resources of current production systems. In this study, several environmental emissions and uses of resources were quantified and qualified where possible