Search results for "shoot"
showing 10 items of 298 documents
Effects of seed production and storage conditions on blackgrass (Alopecurus myosuroides) germination and shoot elongation
2003
Abstract Blackgrass is a common winter annual grass weed in autumn-sown crop rotations in Atlantic European countries. Control with a minimum amount of herbicides in integrated cropping systems would be facilitated by modeling the effect of cropping systems on its demography. To develop the submodel relating weed seed bank to emerged seedlings, laboratory experiments were conducted to analyze and quantify seed germination and shoot elongation. These processes were studied as a function of environmental conditions during seed production (nitrogen availability, water deficit, plant density, and crop) and of seed characteristics (seed weight, harvest date, storage length, and dry-stored/soil-b…
The shoot concept of the flower: Still up to date?
2016
Abstract The shoot concept of the flower suggests that flowers correspond to vegetative short-shoots except the fact that their lateral appendages are floral and not vegetative leaves. However, in view of the different properties of vegetative and flower meristems, this concept should be questioned. Differential meristem activity resulting in tubes, hypanthia and inferior ovaries, continuous meristem expansion providing space for stamen fascicles and additional structures and the process of (repeated) fractionation using a given space completely, are characteristics of flower meristems hardly explainable with the shoot concept. Linking instead flower development with recent findings in mole…
Short-term response of the slow growing seagrass Posidonia oceanica to simulated anchor impact
2007
Experimental evaluations about the impact of anchors of small vessels have previously shown that each anchoring can on average damage up to six shoots of Posidonia oceanica, removing small amount of biomass and, at the same time, interrupting continuity among shoots. The aim of the paper was to investigate the response of P. oceanica to different damage intensity at two levels of substrata compactness. Three treatments were considered: control (no damage); low damage (simulated anchor damage by three strokes of a hoe); and high damage (six strokes). Disturbance was higher where the substratum was highly penetrable and after one year significant variation was observed among treatments for bo…
Vermicompost from municipal sewage sludge affects growth and mineral nutrition of winter rye (Secale cereale) plants
2015
ABSTRACTThe aim of the study was to investigate sewage sludge vermicompost application effects on growth and mineral nutrition of winter rye (Secale cereale L.) plants as compared to two initial levels of mineral nutrient availability, pure sand and sand enriched with inorganic nutrients at the optimal level. Addition of sewage sludge vermicompost significantly inhibited rye seed germination at 20 to 50% sand substitution independently on mineral nutrient supplement. Growth inhibition was evident at early stages of plant development. However, at the later stages, sewage sludge vermicompost acted both as mineral fertilizer and plant growth-promoting agent. Significant stimulation of mineral …
Seedling growth of a native ( Ampelodesmos mauritanicus ) and an exotic ( Pennisetum setaceum ) grass
2016
Scarce information is available on the biological reasons why a small subset of introduced species can effectively establish within novel ecosystems. A comparison of early growth traits can help to explain the better performance of alien invasive species versus native co-occurring species. In one year-long experiment, we compared the early life stages of Ampelodesmos mauritanicus (Poir.) Dur. & Schinz (Amp), a native perennial Mediterranean grass, and Pennisetum setaceum (Forssk.) Chiov (Penn), an emerging invader grass in sub-arid and Mediterranean-climate areas. The Penn seedlings grew significantly faster and were approximately 2.5 times taller than the Amp seedlings, reaching a fina…
Use of biochar as peat substitute for growing substrates of Euphorbia × lomi potted plants
2016
Biochar from conifers wood was used in soilless culture as growing substrate alternative to peat for ornamental crops. Potted plants of Euphorbia × lomi Rauh cv. ‘Ilaria’ were grown with different mixtures (v:v) of brown peat and biochar in order to evaluate main physical and chemical characteristics of this biomaterial as well as its effect on plant growth, ornamental characteristics and nutrients uptake. Biochar addition to peat increased pH, EC and K content of the growing substrates, as well as air content and bulk density. Biochar content of substrates significantly affected plant growth and biomass partitioning: higher number of shoots and leaves, leaf area and leaf dry weight were re…
Long-term effects of elevated CO2 on the population dynamics of the seagrass Cymodocea nodosa: Evidence from volcanic seeps
2021
Population reconstruction techniques was used to assess for the first time the population dynamics of a seagrass, Cymodocea nodosa, exposed to long-term elevated CO2 near three volcanic seeps and compared them with reference sites away from the seeps. Under high CO2, the density of shoots and of individuals (apical shoots), and the vertical and horizontal elongation and production rates, were higher than at the reference sites. Nitrogen limitation effects on rhizome elongation and production rates and on biomass were more evident than CO2 as these were highest at the location where the limitation of nitrogen was highest. At the seep where the availability of CO2 was highest and nitrogen low…
Growth and water relations of field-grown ‘Valencia’ orange trees under long-term partial rootzone drying
2017
Climate, soil water potential (SWP), leaf relative water content (RWC), stem water potential (WPstem), stomatal conductance (g s), trunk, shoot and fruit growth of ‘Valencia’ orange trees were monitored during five consecutive seasons (2007–2012) to study water status and growth responses to irrigation placement or volume. 48 adult trees were exposed to conventional irrigation (CI, 100% of crop evapotranspiration on both sides of the rootzone), partial rootzone drying (PRD, 50% of CI water only on one alternated side of the rootzone) and continuous deficit irrigation (DI, 50% of CI water on both sides of the rootzone). Reducing irrigation volumes by 55% (DI) over CI increased leaf water def…
Water relations and carbohydrate partitioning of four greenhouse-grown olive genotypes under long-term drought
2016
The four olive genotypes exhibited different responses to drought involving leaf drop and g s reductions (broad-leaved genotypes, good leaf hydration); or growth reductions (narrow-leaved genotypes, dehydration tolerance). There was minor effect on carbohydrate levels. Olive plants of broad-leaved ‘Minuta’ (MN) and ‘Nocellara del Belice’ (NB) and narrow-leaved ‘Passulunara’ (PA) and ‘Biancolilla Siracusana’ (BS) were studied to evaluate their responses to drought. In a greenhouse, 2-year-old rooted cuttings were irrigated to field capacity (WW) or with 20% of WW evapotranspiration (DS) for over 3 months. Subsequently, all pots were rewatered to field capacity for 20 days. Gravimetric soil w…
Seasonal changes in starch content in pistachio organs as related to crop load
2018
The alternate bearing in pistachio (Pistacia vera L.) results from inflorescence buds abscission differentiated on current season growth during the year of heavy crop. Inflorescence bud drop has been directly correlated with the presence of fruits on 1-year shoot, and in particular with the kernel grow that acts as the major sink of nutrients. Experimental evidences suggest the involvement of competition between reproductive organs for the available resources. The annual carbohydrates storage was analysed in mature pistachio trees characterized by low, medium and high crop load (about 1, 7 and 11 kg tree(-1) of dry in-shell nuts). The experiment was carried out in 2013 in a commercial pista…