Moreno Toselli

Influence of root pruning and water stress on growth and physiological factors of potted apple, grape, peach and pear trees

Abstract Apple, grape, peach and pear trees were grown with roots divided between two pots for 2 months and then assigned to the following treatments: (1) control, receiving 100% of total plant transpiration (TPT) distributed equally between both pots; (2) pruned, receiving 100% of TPT in one pot with removal of roots in the second pot; (3) stressed, receiving 100% of TPT in one pot with water withheld from the other. Shoot growth of all species except peach was reduced only by root pruning (20%, 30% and 40% less than control in grape, pear and apple, respectively). New root growth of pruned and stressed plants was generally less than control (25% on average). During the first 15 days after treatment, both root pruning and water stress depressed transpiration and net photosynthesis. Thereafter, stressed plants did not differ from control; transpiration and net photosynthesis of pruned plants approached those of control only after 50 days. At the end of the experiment unchanged shoot:root ratios were found in stressed trees of each crop compared with control, while root pruning caused a variable shoot:root ratio depending on the degree of canopy reduction. The findings indicate the ability of the examined crops to adapt to drastic manipulations of the root system.

Determination of the major phenolic compounds in pomegranate juices by HPLC−DAD−ESI-MS.

Traditionally, pomegranate (Punica granatum L.) has been consumed as fresh fruit or as pomegranate juice. In this study, the main phenolic compounds of 12 pomegranate varieties and 5 pomegranate clones were determined by HPLC−DAD−ESI-MS. Two chromatographic methods with a fused-core C18 column and a classical HPLC system were developed. Thirteen anthocyanins and fourteen other phenolic compounds were determined in the pomegranate juices. As far as we are concerned, a new flavonol-glycoside, phellatin or its isomer amurensin, has been tentatively identified for the first time in pomegranate juices. Total phenolic content ranged from 580.8 to 2551.3 mg/L of pomegranate juice. Anthocyanins varied between 20 to 82% of total phenolic content. Flavonoids were 1.6-23.6% of total phenolic compounds, while phenolic acids and ellagitannins were in the range 16.4-65.8%. The five clones reported a phenolic content comparable with that of the other pomegranate samples.

Nitrogen fertilization management in orchards to reconcile productivity and environmental aspects

Nitrogen fertilization in orchards of Emilia-Romagna Region, (Italy) was based in the past on excessive, not split, applications often supplied late in winter; the NUE (Nitrogen Use Efficiency) was therefore low and the risk of nitrate leaching was high. This paper summarizes the studies conducted in the last 10 years at the Department of Horticulture and Forestry of the University of Bologna aimed to develop a more rational use of nitrogen in orchards and vineyards. Root escavation of mature trees revealed that the use of localized irrigation (drip or microjet) causes a concentration of roots in the area wetted by the emitters. In such a situation, band applications of N to the tree row may allow a reduction of amounts of N fertilizer, while widespread applications, especially if the orchard soil is tilled, lead to an accumulation of nitrates in the alley. Results of several field trials where increasing N rates were applied indicate that the kind of response to N supply depends on the presence in soil of natural sources of nitrogen. This fact clearly stresses the necessity of evaluate the N status of an orchard before N fertilization. Rapid estimation of leaf chlorophyll by portable instruments is a promising index of leaf N concentration, only provided that calibration is made for each cultivar. A method, currently under testing in orchards and vineyards of Emilia-Romagna, is proposed here to adjust N fertilizer rates to the demand of the crop and to the level of available N in soil as determined in soil or soil solution samples.

Iron content in vegetative and reproductive organs of nectarine trees in calcareous soils during the development of chlorosis

Abstract We investigated for 2 years (1995–1996) the time course development of chlorosis and the variation of iron (Fe) content in vegetative and reproductive organs in two nectarine orchards planted with cv Spring Red and cv Stark Redgold on calcareous soils of the Po valley (Italy) with the final aim to evaluate possible tools for the early prognosis of Fe chlorosis and a more efficient fertilization management. Due to the withdrawal of Fe supply, floral Fe concentration significantly decreased in 1996 as compared with 1995 in cv Spring Red, but not in Stark Redgold. Correlation coefficients between Fe and chlorophyll (Chl) from the same leaves were always higher when Fe was considered as amount present per leaf or per unit of leaf area than as leaf dry weight. The fact that chlorotic and green leaves had similar Fe concentration could be explained by an overestimate of Fe in the chlorotic leaf as a consequence of a reduction of its size. However, the decrease of Chl concentration between 60 and 120 days after full bloom (DAFB) occurred while leaf Fe content generally increased, indicating that even during chlorosis development leaves were supplied with some iron. We therefore suggest that the development of chlorosis was associated with an inactivation of Fe in the leaf apoplast. In 1995, regardless the cultivar, floral Fe concentration and leaf Chl were never correlated. In 1996 floral Fe concentration was linearly related to leaf Chl recorded 60 and 120 DAFB in cv Spring Red only. Floral Fe concentration at full bloom 1996, regardless the variety, was linearly related to leaf Chl determined in spring of the previous year, suggesting that flower Fe concentration might be used for assessing the storage of iron during the previous season.

Acid-spray regreening of kiwifruit leaves affected by lime-induced iron chlorosis

Kiwifruit (Actinidia deliciosd) vines suffer iron chlorosis when growing in a calcareous soil and symptoms occur despite the presence of medium-to-high concentrations of leaf iron, suggesting the presence of a mechanism that immobilize Fe in plant tissues. In the present study we found a negative correlation between the leaf pH and the chlorophyll concentration in leaves of kiwi vines showing different degrees of chlorosis in calcareous soil and then investigated the effects of acid sprays on chlorotic leaves of kiwi grown in a markedly calcareous soil. The following solutions were sprayed three times at five- and six-day intervals on separate shoots of the same plant (three plants in total): citric acid (2000 mg L-1 and 6000 mg L-1 ), sulphuric acid (38 mg L-1 ), Fe-DTPA ( 130 mg L-1) and deionized water (control). At the end of the trial (19 days from the beginning of treatment application), Fe-chelate caused the most intensive regreening, followed by citric acid (both rates); sulphuric acid caused only a slight increase of leaf chlorophyll as compared to control. The pH of leaves treated with citric but not with sulphuric acid decreased by about 0.2 units as compared to control. Iron-chelate resulted in the greatest increase of both active (extracted by ferrozine) and total iron. The leaves treated with citric acid at both rates also increased their active iron content by about 50% as compared to control leaves. These findings support that high leaf apoplastic pH of plants in calcareous soil is somehow responsible for Fe immobilization and its physiological deficiency.

Biochar physico-chemical properties as affected by environmental exposure

To best use biochar as a sustainable soil management and carbon (C) sequestration technique, we must understand the effect of environmental exposure on its physical and chemical properties because they likely vary with time. These properties play an important role in biochars environmental behavior and delivery of ecosystem services. We measured biochar before amendment and four years after amendment to a commercial nectarine orchard at rates of 5, 15 and 30tha(-1). We combined two pycnometry techniques to measure skeletal (ρs) and envelope (ρe) density and to estimate the total pore volume of biochar particles. We also examined imbibition, which can provide information about soil hydraulic conductivity. Finally, we investigated the chemical properties, surface, inner layers atomic composition and C1s bonding state of biochar fragments through X-ray photoelectron spectroscopy (XPS). Ageing increased biochar skeletal density and reduced the water imbibition rate within fragments as a consequence of partial pore clogging. However, porosity and the volume of water stored in particles remained unchanged. Exposure reduced biochar pH, EC, and total C, but enhanced total N, nitrate-N, and ammonium-N. X-ray photoelectron spectroscopy analyses showed an increase of O, Si, N, Na, Al, Ca, Mn, and Fe surface (0-5nm) atomic composition (at%) and a reduction of C and K in aged particles, confirming the interactions of biochar with soil inorganic and organic phases. Oxidation of aged biochar fragments occurred mainly in the particle surface, and progressively decreased down to 75nm. Biochar surface chemistry changes included the development of carbonyl and carboxylate functional groups, again mainly on the particle surface. However, changes were noticeable down to 75nm, while no significant changes were measured in the deepest layer, up to 110nm. Results show unequivocal shifts in biochar physical and chemical properties/characteristics over short (~years) timescales.

Prevention of Iron‐Deficiency Induced Chlorosis in Kiwifruit (Actinidia deliciosa) Through Soil Application of Synthetic Vivianite in a Calcareous Soil

Abstract In this study we have tested the hypothesis that lime‐induced Fe deficiency chlorosis of kiwifruit may be prevented by the application of a synthetic iron(II)‐phosphate analogous to the mineral vivianite [(Fe3(PO4)2·8H2O)]. Two experiments, under greenhouse and field conditions, were performed. In the greenhouse, 1‐year old micropropagated plants (Actinidia deliciosa, cv. Hayward), grown in 3‐L pots on a calcareous soil, were treated in early autumn with soil‐applied: (1) synthetic vivianite (1.35 g plant−1) and (2) Fe‐EDDHA (24 mg Fe plant−1). The synthetic vivianite suspension, prepared by dissolving ferrous sulfate and mono‐ammonium phosphate, was injected into the soil as a sole application whereas the Fe‐EDDHA solution was applied four times at weekly intervals. The field experiment was conducted in a mature drip‐irrigated kiwifruit orchard located on a calcareous soil in the Eastern Po Valley (Italy). Treatments were performed in early autumn by injecting synthetic vivianite (1.8 kg tree−1) and Fe‐EDDHA (600 mg Fe tree−1) into four holes in the soil around each tree, at a depth of 25–30 cm. The Fe‐chelate application was repeated at the same rate in the following spring. Untreated (control) plants were used in both experiments. Autumn‐applied Fe fertilisers significantly prevented development of Fe chlorosis under greenhouse conditions whereas in the field only vivianite was effective. In conclusion, these 1‐year results show that vivianite represents an effective alternative to soil‐applied Fe chelates for preventing Fe chlorosis in kiwifruit orchards.

Effects of root-zone temperature on nitrogen accumulation by non-bearing apple trees

SummaryNon-bearing, potted, apple plants were subjected to root temperature of 8.6.1(LRT) or 23.6.18C (HRT) and irrigated with 100 ml of water containing 20 mg of N as NH4NO3, in which both ammonium and nitrate-N fractions were enriched in 15N (10 atom%). The root system of each plant was pressurized (325 kPa) at day 1, 2, 4, and 8 after15 N application to evaluate the transport of nitrogen derived from fertilizer (NDFF) through the xylem. This technique was used to investigate N absorption. LRT reduced the rate of N uptake the day after 15N application relative to HRT. Two, 4 and 8.d after fertilization, the rate of exudation and consequently the uptake rate was similar for LRT and HRT. The total amount of N removed by plants after 8.d was not affected by root treatments. Carbon dioxide assimilation, transpiration rate and stomatal conductance were lower for trees subjected to LRT during the time course of the experiment. We suggest that the delay in N absorption was related mostly to the lower activity ...

Counteraction of oxidative damage by pomegranate juice: influence of the cultivar

BACKGROUND Pomegranate (Punica granatum) has gained widespread popularity as a potential functional food due to its high phenolics content. Although in different studies pomegranate juice has been shown to exert anti-atherogenic, anti-inflammatory and antioxidant effects, the cultivar-related differences in phenolics content and antioxidant activity must be carefully taken into account when evaluating the health effects. The first aim of this study was to rank the juices of 15 different varieties of pomegranate according to their total phenolic content and antioxidant capacity. Then three juices were selected, better characterised and added to HepG2 cells as a supplement to evaluate the protective effect against induced oxidative stress. RESULTS The cultivars Wonderful, Hicaz and G2 were chosen according to the ranking and the corresponding juices used at two different concentrations as a supplement to HepG2 cells. Overall, all juices were able to protect cells from oxidative damage, but differences that could be related to the different phenolics content and pattern were detected among the three juices. CONCLUSION Our results show the advantage of screening cultivars prior to efficacy studies. This approach can be useful for food companies that focus on the development of food that has added nutritional and health value.

Response of Potted Pear Trees to Increasing Copper Concentration in Sandy and Clay-Loam Soils

ABSTRACT The response of potted pear trees grafted on quince (Cydonia oblonga Mill.) Sydo stock to increasing concentrations (0, 50, 100, 200, 400, 600, 800, and 1000 mg kg−1) of copper (Cu) in sandy and clay-loam soils were evaluated and crop toxicity thresholds and symptoms were determined. Reductions of shoot growth and leaf area were observed only for pear grown in sandy soil with more than 400 mg Cu/kg. During the growing season, carbon assimilation and soil microbial biomass were reduced as concentration of soil Cu increased. However, the effect was always stronger in sandy than clay-loam soil. Copper accumulated in roots, with response to soil Cu additions described by a linear and a quadratic function for sandy and clay-loam soil, respectively. A possible antagonism was observed between Cu and zinc (Zn) in the roots. Root Zn concentration decreased as soil Cu concentration increased.