Iduna Arduini

Cadmium effects on growth and antioxidant enzymes activities in Miscanthus sinensis

Plants of Miscanthus sinensis (cv. Giganteus) were grown in hydroponics for three months in nutrient solution with 0, 2.2, 4.4 and 6.6 μM CdNO3. Growth parameters, catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities were analysed in leaves and roots collected after 1-and 3-month exposure. Dry biomass of all miscanthus organs was affected by Cd concentration both after 1-and 3-month exposure. No visible symptoms of Cd toxicity were observed in shoots and rhizomes of plants grown in presence of Cd. In contrast, roots became shorter and thicker and the whole root system more dense and compact already after one month of treatment with 6.6 μM Cd. The lower Cd concentration increased the enzymes activities after 3 months in leaves and only after 1-month in roots, while a decrease in activity was observed at higher Cd concentrations.

The Response of Durum Wheat to the Preceding Crop in a Mediterranean Environment

Crop sequence is an important management practice that may affect durum wheat (Triticum durum Desf.) production. Field research was conducted in 2007-2008 and 2008-2009 seasons in a rain-fed cold Mediterranean environment to examine the impact of the preceding crops alfalfa (Medicago sativa L.), maize (Zea mays L.), sunflower (Helianthus annuus L.), and bread wheat (Triticum aestivum L.) on yield and N uptake of four durum wheat varieties. The response of grain yield of durum wheat to the preceding crop was high in 2007-2008 and was absent in the 2008-2009 season, because of the heavy rainfall that negatively impacted establishment, vegetative growth, and grain yield of durum wheat due to waterlogging. In the first season, durum wheat grain yield was highest following alfalfa, and was 33% lower following wheat. The yield increase of durum wheat following alfalfa was mainly due to an increased number of spikes per unit area and number of kernels per spike, while the yield decrease following wheat was mainly due to a reduction of spike number per unit area. Variety growth habit and performance did not affect the response to preceding crop and varieties ranked in the order Levante > Saragolla = Svevo > Normanno.

Nitrogen leaching and residual effect of barley/field bean intercropping

Cereal/legume intercropping may improve resource use efficiency in agroecosystems and increase yield per unit surface area and yield stability. Two field bean ( Vicia faba L.) and four barley ( Hordeum vulgare L.) cultivars were mono- and intercropped (additive design) in a 2-year lysimeter experiment on a sandy loam soil. The aim was to test the effect of the cropping system on dry matter and N yield of forage, the residual effect on the subsequent ryegrass crop ( Lolium multiflorum Lam. westerwoldicum ), and NO 3 -N leaching in the rotation. Land equivalent ratios were 1.65 for dry matter and 1.67 for N yield, indicating a clear advantage of the intercrop over sole crops. Both species suffered from competition, especially in terms of N resources, but barley was less affected. Nitrate leaching was the lowest from intercrop. Preceding crop significantly affected dry matter, N content and NO 3 -N leaching of ryegrass. Field bean sole crop gave the highest benefits to ryegrass in terms of forage dry matter and N content, but also the highest NO 3 -N leaching, followed by the intercrop and the barley sole crop. Barley/field bean intercropping may be an effective strategy to reduce land requirements, N leaching losses and fertilizer inputs, thereby increasing the sustainability of farming systems.

Dry matter accumulation and remobilization of durum wheat as affected by soil gravel content

Soil gravel content affects many soil physical properties, i.e. bulk density, porosity, water infiltration and storage, as well as crop yield. Little is known regarding the influence of soil gravel content on grain yield of durum wheat ( Triticum durum Desf.). In this paper the accumulation of dry matter during the vegetative and reproductive periods and the contribution of pre-anthesis assimilates to grain yield have been evaluated in two durum wheat varieties grown on soils with 0, 10, 20, and 30% gravel content. The two varieties showed similar behaviour and more soil gravel decreased plant biomass both at anthesis and at maturity. Soil gravel content greatly reduced grain yield and dry weight of all plant parts both at anthesis and maturity. Post-anthesis dry matter accumulation was 16% lower in plants grown on 30% gravel soil and dry matter remobilization was 53% lower, compared to plants grown in gravel-free soil. The differences in growth rate were attributed to the restriction of the volume of soi...

Coordination between plant and apex development in Hordeum vulgare ssp. distichum

Developmental scales for cereals describe apex and plant morphology separately. In order to link crucial steps of internal and external development, in three varieties of Hordeum vulgare spp. distichum L., sown in autumn and in spring, we recorded plant, leaf and apex stage, following the scales of Zadoks, Haun, and Banerjee and Wienhues, the number of primordia, culm and spike length, and the final number of leaves and spikelets. Primordia initiation was coordinated with leaf appearance and the relative rate was constant for the initiation of productive primordia. The maximum number of primordia was achieved just before the first node became detectable, but development was completed only by those initiated before floret differentiation and internode distension started. The first spikelet was initiated when the third leaf tip became visible, and the last one when plants were at the pseudo stem erection stage and five leaves had still to appear.

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.

Grain legumes differ in nitrogen accumulation and remobilisation during seed filling.

ABSTRACT In grain legumes, the N requirements of growing seeds are generally greater than biological nitrogen fixation (BNF) and soil N uptake during seed filling, so that the N previously accumulated in the vegetative tissues needs to be redistributed in order to provide N to the seeds. Chickpea, field bean, pea, and white lupin were harvested at flowering and maturity to compare the relative contribution of BNF, soil N uptake, and N remobilisation to seed N. From flowering to maturity, shoot dry weight increased in all crops by approximately 50%, root did not appreciably change, and nodule decreased by 18%. The amount of plant N increased in all crops, however in field bean (17 g m−2) it was about twice that in chickpea, pea, and lupin. The increase was entirely due to seeds, whose N content at maturity was 26 g m−2 in field bean and 16 g m−2 in chickpea, pea, and lupin. The seed N content at maturity was higher than total N accumulation during grain filling in all crops, and endogenous N previously accumulated in vegetative parts was remobilised to fulfil the N demand of filling seeds. Nitrogen remobilisation ranged from 7 g m−2 in chickpea to 9 g m−2 in field bean, and was crucial in providing N to the seeds of chickpea, pea, and lupin (half of seed N content) but it was less important in field bean (one-third). All the vegetative organs of the plants underwent N remobilisation: shoots contributed to the N supply of seeds from 58% to 85%, roots from 11% to 37%, and nodules less than 8%. Improving grain legume yield requires either reduced N remobilisation or enhanced N supply, thus, a useful strategy is to select cultivars with high post-anthesis N2 fixation or add mineral N at flowering.

Sowing date affect spikelet number and grain yield of durum wheat

Shifts in sowing date change the combination of temperature and photoperiod to which durum wheat is exposed, affecting crop phenology and grain yield. Three durum wheat ( Triticum turgidum L. var. durum ) varieties were field sown at month intervals over a whole year. The number of spikelets on the main culm and the duration of the period of spikelet initiation were recorded. Grain yield, spike number, and mean kernel weight were determined, too. With all sowing dates, plants formed a spike within the main culm and reached the stage of first node detectable. Physiological maturity was achieved only for sowings performed between October and May. Grain yield was highest in November and both yield and yield components were strongly affected by sowing date. The number of spikelets ranged from 11 to 24, according to sowing date and variety. It decreased from November to May in consequence of the shorter initiation period, and we hypothesize that a 12-h-daylength or longer interrupts spikelet initiation. The de...

A growth scale for the phasic development of common buckwheat

Growth scales give a standardized definition of crop development and increase the understanding among researchers and growers. In this research we defined a growth scale for the phasic development of common buckwheat that was mainly based on a sequence of easily recognizable changes occurring on the first and the terminal clusters of inflorescences formed on the main stem. Observations were carried out on plants grown in two years throughout spring. In an attempt to uniform the duration of phasic development across sowing dates, the length of phases and sub-phases was calculated in days and in thermal time using nine combinations of cardinal temperatures. A sequence of stages and various patterns of coordinated development were maintained throughout all sowings and years. Specifically, (1) the first inflorescence became visible after three true leaves had fully expanded on the main stem; (2) flowering reached the terminal inflorescence cluster before full-sized green fruits became visible in the first inflorescence, and (3) fruit ripening in the whole plant ended within two weeks of the end of ripening in the oldest inflorescence. Plant size was increased with the delay of sowing, and the length of the growth cycle was by approximately 400°Cd longer when plants experienced a day length longer than 15 h. This changed the correspondence between flowering and ripening stages, so that full flowering was associated with the development of green fruits in the first inflorescence when the cycle was short, but with their development in the terminal cluster when it was long. Trends in grain yield did not correspond to those in plant size and phase length. We are confident that this growth scale will be a valuable tool for following the progress of buckwheat development and to predict growth patterns and harvest time in response to temperature and photoperiod.

Recovery of understory vegetation in clear-cut stone pine (Pinus pinea L.) plantations

Abstract The recovery of understory vegetation after clear-cutting of stone pine (Pinus pineaL.) plantations is crucial for biodiversity conservation. The development of plant cover, and the richness, diversity and composition of understory plant communities were investigated within five years from clear-cutting. After three years, plant cover ranged from 48 to 74%, and was formed by over 90% of shrubs and graminoids. Diversity decreased in cut plots and the index of similarity showed marked shifts in species composition. Richness increased and around 50 new species per plot were inventoried over three years. New species showed a high proportion of annuals with broad ecological amplitude and aliens, which changed life form and chorology spectra. Most new species had low frequency, but some were still present after five years. Extinction of resident species was low, and their frequency increased with time from clear-cutting. Most of them were perennials with sprouting ability. Common features of plant communities developing in clear-cut stone pine plantations were: (1) the linear increase of plant cover during the first three growing seasons, (2) increased species richness, (3) decreased diversity, (4) invasion by annuals, and (5) invasion by Alien and Cosmopolitan species.