Mulching with almond hull and olive leaves for weed control in fennel (Foeniculum vulgare Mill.) and flower beds

Weeds are a major problem in cropping systems and in urban areas. The aim of this study was to assess the effectiveness of organic mulching with olive leaves and almond hulls to control weeds in fennel (Foeniculum vulgare Mill.) and in flower beds (urban areas). A 3-cm thick layer of olive leaves or almond hulls was applied as mulching material in fennel. Control consisted of both an unmulched treatment and a weed free control. Moreover, in a flower bed of a railway station, plots mulched with 3 cm layer of olive leaves and almond hulls were compared with an unmulched treatment. Weed infestation was evaluated and the weights of the whole plant and of the marketable part of fennel (grumolo) measured. Mulching with olive leaves and almond hulls reduced weed infestation in both vegetable crop and flower beds. However, olive leaves reduced the weights of the whole plant and of the grumolo. The adoption of almond hulls and olive leaves as organic mulches could be an effective strategy for weed control. Further investigations should be carried out to assess whether the effectiveness of these mulching materials is mainly due to a mechanical activity or allelopathic compounds also play a significant role in weed suppression

Yield, quality, antioxidants and elemental composition of peanut as affected by plant density and harvest time

With the perspective of reintroducing peanut cultivation in southern Italy about six decades after its dismissal, research was carried out with the aim to identify the best performing farming management in terms of yield and quality. In this respect, the effect of the factorial combination between four plant densities (6.1, 7.8, 10.3, and 12.1 plants m-2) and two harvest times (100 and 110 days after planting) was assessed on pod and seed yield, as well as on seed quality, antioxidant activity, and elemental composition. The later harvest time determined a 26.9% dry weight increase, but a 14.3% decrease in the number of seeds per pod. Plant density significantly influenced all the yield and growth indices except for mean seed weight. Yield and growth of each plant were best affected by the lowest plant density, whereas the opposite trend was recorded for the same parameters referred to the surface area unit. The density of 12.1 plants m-2 resulted in a 32% reduction in pods per plant compared to 6.1 plants m-2, but had the greatest effect on seed production per m-2. The leaf area index was the highest with the density of 12.1 plants m-2. The total dry weight increased by 1.7-fold from 6.1 to 12.1 plants m-2. Compared to the first harvest time, in the second one the protein content decreased by 6.8%, and total polyphenols and antioxidant activity decreased by 11.2% and 7.6%, respectively. The second harvest time led to a depletion of N, P, and Mg, by 6.8%, 6.2%, and 6.8%, respectively, and a 7.1% Ca increase. The reintroduction of peanut cultivation in southern Italy is a realistic goal, though further studies regarding the crop system management are needed.

Molecular inference of subgenus Hermodactyloides Spach for vascular flora of Iraq

Iris reticulata of sect. Reticulata from subg. Hermodactyloides in Iraq have been circumscribed based on morphological characters long time ago. Recent work, carried out in neighbouring countries (Turkey and Iran), added the new sect. Zagrica, which includes four new species. No molecular study has been performed yet to confirm the status of this subgenus. In this work, a phylogenetic study of the subg. Hermodactyloides was carried out by using internal transcribed spacer (ITS) region as well as morphological traits, with the aim to examine this subgenus in Iraq. Molecular data indicate that a new section is diverged from Hermodachtyloides and should be added to vascular flora of Iraq as a second section named Zagrica. This outcome is consistent with the morphological description. This work also implies that leaf transverse section should be considered as main morphological characters to be taken into account to separate the Reticulata section from Zagrica which has the same taxonomical value as the position of ovary (above ground or subterranean).

Evaluation of nutrients removed and recycled in a commercial peach orchard over a 14-years-production cycle

Understanding nutrient dynamics within a peach orchard is fundamental to the development of accurate nutrient management practices. The present study investigated the nutrient uptake and redistribution in a 14-years-old commercial orchard in the Po valley. At the end of the experiment, trees were harvested, biomass and organ nutrient concentration were determined. Skeleton and roots accounted for the highest plant biomass, followed by fruits at harvest, pruned wood and abscised leaves; thinned fruits were less than 1 kg tree-1. The difference between the amounts of nutrients in leaves sampled in summer and in autumn (at abscission) was used to estimate the fraction of nutrients remobilized during the vegetative season inside the tree. The decrease of N, P, S, Cu, Mn and Zn concentration in abscised, compared to summer-sampled leaves was the result of the translocation of nutrients into fruits and storage organs. Nutrient circulation in a commercial nectarine orchard was calculated by determination of the fractions of each nutrient recycled (sum of nutrients in abscised leaves, thinned fruits and pruned wood) and remobilized (sum of nutrients in fruits at harvest, roots and skeleton). In our experimental conditions, on average, nectarine Stark RedGold showed an annual request of (in kg ha-1) 100, 17, 73, 129, 16, and 6 of N, P, K, Ca, Mg and S, respectively. More than half of these quantities were recycled in the orchard and returned back to the soil; consequently, if the nutrient use efficiency is maximized, the fertilization of nectarine requires only small amount of external inputs.

Sr isotope ratio in vegetable crops and apple trees depends on that of the soil environment while is unaffected by the genotype

The 87Sr/86Sr ratio is an effective geographical tracer for horticultural products. In plants this ratio reflects closely the characteristics of the growing area. However, information about the variability of this parameter when measured in different plant species or cultivars is still scarce. In this work, we have tested the hypothesis that, when plants are growing in the same environment, their 87Sr/86Sr ratio is independent from the plant species or cultivar. For this, four to six vegetable species were collected from two fields in different locations in South Tyrol (Italy), together with the corresponding soils. Additionally, within a single apple orchard located in the same area, apple leaves were collected from trees of five cultivars. The 87Sr/86Sr ratio was measured applying an established and validated method. In general, vegetable species growing in the same field had similar 87Sr/86Sr ratios and showed a lower variability compared to their corresponding soils, while a significant difference was found comparing the 87Sr/86Sr ratios of the two vegetable fields. Apple leaves sampled from different tree cultivars also did not show a significant difference in their 87Sr/86Sr ratio. We concluded that the 87Sr/86Sr ratio in vegetables and apple trees was affected by the soil, but not significantly by the type of species or cultivar. Therefore, within limited areas, the results of the 87Sr/86Sr ratio analysis based on samples of a certain species/cultivar can be extended to other similar plants growing in the same site.

Foliar and root uptake of N deriving from simulated atmospheric N depositions in potted apple (Malus domestica) trees

A significant human-driven increment of the available reactive nitrogen (Nr) forms has occurred during the past century at the global scale, which in turn has increased the amount of Nr deposition. Grafted apple trees (Gala / M.9 strain T337) were used in a pot experiment conducted in semicontrolled conditions, where the 15N-labelling technique allowed to trace the fate of N from ammonium nitrate (15NH4 15NO3, isotopic enrichment: 10.3 atoms %) distributed at three increasing rates (N1, N2, N4, where N2 is the double of N1 and N4 is the double of N2) either to soil or to canopy (foliar application) to simulate atmospheric N depositions. At the end of the experiment, plants were destructively sampled, and N derived from depositions (Ndfd), total N, and biomass of above and belowground organs were determined. Uptake rates ranged from 21% to 57% and the Ndfd recovery was higher for soil than for foliar application. Foliar-supplied plants showed a higher Ndfd in leaves and shoots than soil-supplied ones, while the latter showed a higher Ndfd in roots than the former. Moreover, total N in trunk, shoot axes and leaves increased with the N rates up to the level N2, with no further increase in N4. Increasing tree N availability, regardless the supply mode, increased the shoot:root N content. The fact that the N uptake rate was rather stable at increasing N rates suggests that if N from atmospheric depositions becomes increasingly available at the canopy or soil level, it will actively contribute to apple tree nutrition and account for a significant fraction of the apple tree N needs.