Fabrizio Leteo

Variations in the phytochemical contents and antioxidant capacity of organically and conventionally grown Italian cauliflower (Brassica oleracea L. subsp. botrytis): results from a three-year field study.

A three-year field study (2009-2011) was performed to evaluate phytochemicals and antioxidant capacities of two genotypes (HF1 Emeraude and the local variety, Velox) of green cauliflower grown under organic and conventional management. The conventional system increased yield, but had little effect on the dry matter, whereas the organic system increased the soluble solids. Phytochemicals and antioxidant capacity showed significant year-to-year variability. During the third year, the scarce rainfall determined a significant increase of total glucosinolates and a general decrease of antioxidants in all samples. Interestingly, in the same year organic plants were less affected by the unfavorable climatic conditions, as they increased ascorbic acid, polyphenols, and carotenoids with respect to conventional ones. The overall results for the three years showed that the two genotypes responded differently. Compared to the conventional system, Velox showed 24, 21, 13, 48, and 44% higher content of ascorbic acid, polyphenols, carotenoids, volatiles, and antioxidant capacity, respectively. In contrast, no significant increase in the phytochemicals or the antioxidant potential was found in organic Emeraude, with the exception of total volatiles (+41%). These findings suggest that organic cultivation may be highly effective for particular cauliflower genotypes.

Long-term impact of farm management and crops on soil microorganisms assessed by combined DGGE and PLFA analyses

In the present study, long-term organic and conventional managements were compared at the experimental field of Monsampolo del Tronto (Marche region, Italy) with the aim of investigating soil chemical fertility and microbial community structure. A polyphasic approach, combining soil fertility indicators with microbiological analyses (plate counts, PCR-denaturing gradient gel electrophoresis [DGGE] and phospholipid fatty acid analysis [PLFA]) was applied. Organic matter, N as well as some important macro and micronutrients (K, P, Mg, Mn, Cu, and Zn) for crop growth, were more available under organic management. Bacterial counts were higher in organic management. A significant influence of management system and management x crop interaction was observed for total mesophilic bacteria, nitrogen fixing bacteria and actinobacteria. Interestingly, cultivable fungi were not detected in all analyzed samples. PLFA biomass was higher in the organic and Gram positive bacteria dominated the microbial community in both systems. Even if fungal biomass was higher in organic management, fungal PCR-DGGE fingerprinting revealed that the two systems were very similar in terms of fungal species suggesting that 10 years were not enough to establish a new dynamic equilibrium among ecosystem components. A better knowledge of soil biota and in particular of fungal community structure will be useful for the development of sustainable management strategies.

Ecological Sustainability of an Organic Four-Year Vegetable Rotation System: Carabids and Other Soil Arthropods as Bioindicators

A four-year investigation comparing organic and conventional horticultural vegetable rotation systems was carried out in Central Italy using soil arthropods as bioindicators. The indexes of biodiversity showed, in general, higher values on organic in comparison with conventional management, but the differences were strongly affected by the crops. An index specifically designed to select the Carabid species, which benefit from organic versus conventional, was calculated in order to understand faunistic data on this group. Our data demonstrated that the spray intensity adversely affects the Carabid species richness, as proved by the lowest diversity values recorded in the conventional plots. The experiment, planned by following a “system approach research,” was suitable to understand the ecological sustainability in organic farming in comparison with conventional. The better conservation of arthropod fauna in the organic seems to be coherent also with the enhancement of organic matter in this system. For this reason, a holistic effect of the organic system can provide a reasonable interpretation of the better conservation of the living component and, in particular, of Carabid beetle biodiversity, during the four-year period.

Effect of roller-crimper technology on weed management in organic zucchini production in a Mediterranean climate zone

Integrating cover crops into vegetable cropping systems can provide a wide range of ecological services, of which weed management is a key component. Cover crop effects on weed control, however, are dependent on termination methods and weed species present in specific cropping seasons. A 2-year weed management experiment with two cultivars of organic zucchini ( Cucurbita pepo L.) in central Italy was carried out to compare the effect of a barley ( Hordeum distichum L.) cover crop terminated with a modified roller-crimper (RC) to incorporated barley as green manure (GM) and a tilled control left fallow (FA) in the off-season. The effects of cover-crop management on crop competitiveness, yields and weed populations were evaluated by direct measurement, visual estimation and competition index methods. Results showed a significant reduction in weed biomass (>80%) and weed abundance with the RC compared to the GM and FA treatments. Moreover, the RC barley mulch maintained weed control in zucchini plots even under high weed pressure, as determined by the agronomic tolerance to competition (ATC) value of 67% in the RC treatment compared to 40 and 34% in the FA and GM treatments, respectively, averaged over both years of the experiment. The competitive balance ( C b ), which quantified the ability of the zucchini crop to compete with weed populations, was also greater (+0.37) in the RC treatment compared to FA (−0.87) and GM (−0.69) treatments over the same period. Zucchini crop biomass was greatest in the RC treatment in 2011. Zucchini fruit yields varied from an average over both years of 1.4 Mg ha −1 in the RC treatment to 0.7 Mg ha −1 in the GM treatment, but yields in the FA treatment, 1.2 Mg ha −1 , did not differ from the RC treatment. No differences in yield between ‘Dietary’ and ‘Every’ zucchini, or any significant interactions between cultivar and cover management related to fruit biomass, were observed. Our findings suggested the viability of the modified RC in creating a barley cover-crop mulch to effectively manage weeds and enhance yields in transplanted zucchini.

Effectiveness of living mulch strategies for winter organic cauliflower (Brassica oleracea L. var. botrytis) production in Central and Southern Italy

In crop rotations, cover crops planted either before or concurrent with a main crop and maintained as a living ground cover (living mulch, LM) may provide many beneficial ecosystem services, and can be defined as ‘agro-ecological service crops’ (ASC). The objective of this research was to study the suitability of burr medic ( Medicago polymorpha L. var. anglona ) as an LM for organic cauliflower ( Brassica oleracea L. var. botrytis ) production in a Mediterranean environment. Two LM sowing times (early sowing – sowing concurrent with cauliflower transplanting versus late sowing – 3 weeks later) compared with a no living mulch control (LM-CT) were investigated in central Italy (Experiment 1), along with a comparison between two local cauliflower cultivars and a hybrid. In Southern Italy (Experiment 2), crop performance under two LM sowing times [20 days before cauliflower transplanting versus concurrent sowing (CS)] compared with a no LM-CT , with organic fertilizers and amendments allowed in organic farming as subplots, was assessed. In Experiment 1, no competition was observed between the late-sown ASC and the cash crop. An increase in crop nitrogen (N) uptake and weed mitigation was also determined in this treatment. There was a mixed response when comparing cultivar and LM interactions, with the hybrid cultivar in the late-sown LM producing the greatest yield. In Experiment 2, weather conditions had the greatest effect on crop response. However, an inverse trend between growth of the cash crop and the LM crop was observed in the CS treatment. A positive effect of LM introduction was found, particularly in altering the competitive relationship for N between the cash crop and weeds. In addition, yield results showed that, in LM systems, commercial organic fertilizers could be replaced with locally available organic fertilizers and amendments without any yield penalty. The effectiveness of LM strategies will thus depend on several factors: type of LM, cultivar of vegetable, weather, soils, length of growing season and ability to plant the cash crop into the LM. Initial research suggests the potential for burr medic as a LM for Mediterranean winter vegetable systems, but additional research is needed to ensure the viability of LM systems for longer periods of time.

Living mulch for weed management in organic vegetable cropping systems under Mediterranean and North European conditions

The aim of this study was to investigate the effect of growing in-season agro-ecological service crops as living mulch (LM) with vegetable crops, exploiting their potential to suppress weeds by filling the ecological niches otherwise occupied by weeds. Two field experiments were carried out in Denmark and Italy to compare different LM introduction strategies in organic vegetable cropping systems. In Denmark, leek ( Allium porrum L.) was grown with dyers woad ( Isatis tinctoria L.) LM strips, while cauliflower ( Brassica oleracea L. var. botrytis ) was intercropped with a broad sowed burr medic ( Medicago polimorpha L., var. a nglona ) in Italy. Two LM times of sowing relative to cash crop transplanting––an early sowing (es LM) and a late sowing (ls LM)––were compared with a control with no LM (no LM). The effects of LM treatment on crop competitiveness, LM smother effect and weed populations were evaluated by direct measurement, visual estimation and competitive index methods. Comparison among hybrid and open pollinated cultivar responses to LM introduction was also performed. Results showed a significant higher cash crop biomass in ls LM than in es LM, with comparable yield to the weeded controls, except for es LM in Italy. Moreover, in the Danish experiment, the LM and weed biomasses were up to 5 times lower in the es LM and ls LM treatments than the weed biomass alone in no LM treatment. Reduction in weed biomass and abundance was observed also in ls LM in the Italian trial. Similarly, the competitive balance (C b ), which quantifies the ability of the cash crop to compete with neighbours, was higher in the es LM (+0.29) and ls LM (+0.72) compared with unweeded no LM control (−0.86) in Denmark. In the Italian experiment, the cauliflower showed more competitive ability against neighbours in ls LM (+0.53) and was a weak competitor in es LM (−1.51). The cash crop had higher competitive ability against LM (C b c-lm) when sowing was more delayed in both experiments, while, in the Italian trial, the LM was more competitive against weeds (C b lm-w) in ls LM (+1.54) than in es LM (−0.41). The slight differences observed for biomass and competitive ability between the tested cultivars, highlighted similar suitability of both hybrid and open-pollinated cultivars to grow with LM. Our findings suggest the viability of the introduced LM in managing weeds and avoiding a smother effect on the crop, with particular effectiveness with delayed LM sowing.