Recover of understory vegetation in clearcut stone pine (Pinus pinea L.) plantations

The recovery of understory vegetation after clear-cutting of stone pine (Pinus pinea L.) 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

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

Biosolids affect the growth, nitrogen accumulation and nitrogen leaching of barley

Biosolids are organic fertilisers derived from treated and stabilised sewage sludge that increase soil fertility and supply nitrogen to crops over a long period, but can also increase the risk of nitrogen (N) leaching. In this work, spring barley was grown in lysimeters filled with soil amended with biosolids, and with and without mineral N fertilisation. Biomass and the N concentration and content of shoots and roots were determined at flowering and maturity, and the N remobilization was calculated during grain filling. Drainage water was collected and analysed for N leaching. Biosolids increased soil porosity and soil nitrate, and positively affected the growth and N uptake of barley. Compared to mineral fertilisers, biosolids produced 18% higher vegetative biomass and 40% higher grain yield. During grain filling, both N uptake and N remobilization were higher with biosolids, which increased the grain N content by 32%. Nitrogen loss in leachates was 1.2% of plant uptake with mineral fertilisers and 1.7% with biosolids. Thus, soil fertilisation with biosolids greatly benefits spring barley, only slightly increasing N leaching

Forage and grain yield of common buckwheat in Mediterranean conditions: Response to sowing time and irrigation

With the view to extending the cultivation of common buckwheat to Mediterranean environments, we investigated the responses of two varieties to three sowing times, early spring, late spring and late summer, in rainfed and irrigated conditions. Plants were harvested at two ripening stages for forage production and at maturity for grain yield. The crop cycle lasted 82-88 days independent of sowing time, whereas the thermal time was ∼1000 degree-days in early spring and late summer sowings, and 1200 degree-days when sown in late spring. Forage yield increased up to 75% between ripening stages. Early spring was the best sowing time for forage (4tha-1 dry weight) and grain yield (2tha-1 dry weight) in rainfed conditions. Late spring sowings give the highest forage yield when irrigated (6tha-1 dry weight), but were not suitable for producing grain, for the adverse effect of high summer temperatures on seed set and seed filling. Late summer sowings produced acceptable grain yield (1.5tha-1 dry weight), whereas short days and low temperatures limited forage production. Thus, in Mediterranean environments, buckwheat could be profitably introduced as a minor summer crop, sown in early spring for grain production and in late spring for forage production

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

n 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

Field Inoculation of Bread Wheat with Rhizophagus Irregularis under Organic Farming: Variability in Growth Response and Nutritional Uptake of Eleven Old Genotypes and A Modern Variety

Arbuscular mycorrhizal fungi (AMF) promote crop growth and yield by increasing N and P uptake and disease resistance, but the role of field AMF inoculation on the uptake of micronutrients, such as Fe and Zn, and accumulation in plant edible portions is still not clarified. Therefore, we studied the effect of field inoculation with Rhizophagus irregularis in an organic system on 11 old genotypes and a modern variety of bread wheat. Inoculation increased root colonization, root biomass and shoot Zn concentration at early stage and grain Fe concentration at harvest, while it did not modify yield. Genotypes widely varied for shoot Zn concentration at early stage, and for plant height, grain yield, Zn and protein concentration at harvest. Inoculation differentially modified root AMF community of the genotypes Autonomia B, Frassineto and Bologna. A higher abundance of Rhizophagus sp., putatively corresponding to the inoculated isolate, was only proved in Frassineto. The increase of plant growth and grain Zn content in Frassineto is likely linked to the higher R. irregularis abundance. The AMF role in increasing micronutrient uptake in grain was proved. This supports the introduction of inoculation in cereal farming, if the variable response of wheat genotypes to inoculation is considered

Root dynamics and soil-enzyme activities in field bean/barley intercrops

The study and design of cropping systems that better exploit ecological processes is a priority of the scientific community and intercrops, involving two or more crop species growing simultaneously on the same field, are considered valuable to increase the productivity of traditional family farming and for the sustainable intensification of industrial agriculture. Advantages of intercrops are based on ecological principles such as diversity, complementarity, facilitation and replacement, which are enhanced in cereal/legume associations because of the differences in the morphology and distribution of the root systems and in the use of different N sources. Understanding the complexity of plant-plant and plant-soil interactions is crucial because beneficial complementarity and facilitation relationships can rapidly turn into negative competition. The field experiment consisted of a barley (Hordeum vulgare L. subsp. polystichum, var. Jallon) field bean (Vicia faba minor Beck, var. Vesuvio) intercrop (IC) and the respective sole crops (SC) grown at low (0 kg ha-1) and high (120 kg N ha-1 and 100 kg P ha-1) fertilizer inputs. Seed density was100 seeds m-2 for Fb, 250 seeds m-2 for B, and 100:125 seeds m-2 in the Fb:B IC, where plants were arranged in a 1:1 row ratio spaced 15 cm. At barley heading, soil and root samples were collected from the 0-20 cm soil profile and roots were cleaned from the soil with a water flow and then separated by species. Root morphological traits such as length, diameter, surface area and volume were analysed with WinRhizo, then samples were oven dried. On soil samples dehydrogenase, ß-glucosidase, alkaline phosphatase and arylsulphatase activities were determined, and the geometric mean (GMea) of the assayed soil enzyme activities was calculated. Root density of IC was intermediate between Fb and B SC, the former displaying the highest density on dw basis, the latter on length basis. In both SCs root density was higher without fertilizer input, demonstrating a higher investment in roots in response to NP limitation. In contrast, fertiliser input increased root density in the IC, which we interpreted as a competitive root growth stimulated by the higher nutrient availability in soil. The specific root length (SRL, m/g) increased in Fb SC in response to NP supply, demonstrating an energy investment in root elongation instead in feeding N2-fixing bacteria when mineral N was available, which is confirmed by the lower nodule density. The opposite occurred in the B SC, where SRL was reduced by mineral supply. In the IC, NP input increased the SRL of both species, demonstrating strong interspecific competition for nutrient acquisition and not complementarity, as it is generally supposed for cereal/legume intercrops. As a result of the higher investment of resources in root elongation, in Fb, nodule density decreased dramatically. In the fertilized IC soil also the GMea was higher, suggesting a major production of exudates from roots

Submergence sensitivity of durum wheat, bread wheat and barley at the germination stage

Soil waterlogging at initial growth stages can cause heavy yield losses of winter cereals. Therefore, the screening for submergence tolerance traits in seeds of commercial varieties is of high concern worldwide. Ten Italian varieties of durum wheat (Triticum durum Desf.), bread wheat (T. aestivum L.) and barley (Hordeum vulgare L.) were investigated for their ability to germinate in submerged conditions and to recover after submergence periods of three to 15 days. Submergence prevented germination and decreased germinability, at rates that increased with duration of submergence. Sensitivity ranked in the order: barley >durum wheat >bread wheat. We related the higher sensitivity of barley to its slower germination and slightly higher leakage of electrolytes, whereas the percentage of abnormal seedlings was lower than in other species. It was less than 4%, compared to less than 15 and 8% in durum wheat and bread wheat, respectively. Wide varietal differences were found in all species. According to variety, after 6-day submergence, germinability ranged from 2 to 42% in barley, from 5 to 80% in durum wheat, and from 30 to 77% in bread wheat. Varieties with more than 40% seed survival were three, six and seven per species, in the same order. The differential submergence sensitivity of varieties indicates a potential to select for waterlogging tolerance within Italian genotypes of winter cereal crops

Forage potential of winter cereal/legume intercrops in organic farming

This research was performed to assess the potential of cereal/legume intercropping to enhance forage yield and quality when compared with cereal sole crops under the constrains imposed by UE organic farming regulations. Sole crops (SC) and intercrops (IC) of two winter cereals, barley (Hordeum vulgare L.) and durum wheat (Triticum durum Desf.), and two legumes, white lupin (Lupinus albus L.) and common vetch (Vicia sativa L.), were evaluated at two harvest times for dry matter yield (DMY), crude protein concentration (CPC), and nitrogen yield (NY). Yield values and dry matter concentration (DMC) were generally higher when cereals were at the hard dough compared to the late milk stage. On average, intercropping increased forage yield by 72%, NY by 190%, and CPC by 40 g kg-1, compared to cereal sole crops, but the choice of legume species affected the yield advantage and the composition of forage. Land equivalent ratio (LER) of intercrops was always higher than 1, ranging from 1.39 to 1.61. Intercropping also enhanced weed suppression, compared to sole crop