A FUNCTIONAL AGROBIODIVERSITY APPROACH TO IMPROVE ORGANIC WHEAT PRODUCTION

Crop agrobiodiversity is an asset to improve organic and low-input wheat production, but a clear framework is necessary to translate scientific evidences into practice. Here we present results from a field experiment on common wheat, focusing of cultivar identity, genetic heterogeneity and on the inclusion of a legume living mulch. This experiment provided us insights on how to improve yield, yield stability and weed reduction through adequate cultivar choice and diversification of the crop stand

Mixtures of Commercial Lentil Cultivars Show Inconsistent Results on Agronomic Parameters but Positive Effects on Yield Stability

Cultivar mixtures are a useful tool to enhance cultivated biodiversity to buffer crop biotic and abiotic stresses. There are multiple pieces of evidence of mixture advantages in terms of pathogen control and increase in yield amount, stability and quality. Lentil represents a founder crop in the Mediterranean, yet it experiences strong yield fluctuations in the face of abiotic stresses. The present study aims to assess the mixing ability of four Italian commercial lentil lines in terms of yield amount and stability, nodule number, total lentil biomass and sensitivity to weeds. Since there is very limited information on lentil genotype traits, two-, three- and four-cultivar mixtures were designed with a trait-blind approach and compared to sole cultivars. The nodule number was mainly influenced by cultivar and weather; no interaction between cultivars was observed. Treatments were differently sensitive to weeds, but the effect of spatial heterogeneity prevailed over that of the cultivar. The average yield stability of all mixtures was significantly higher than pure stands, but in terms of yield amount, individual mixtures either outperformed or were outperformed by pure stands. Against our expectations, cultivar mixtures showed the most advantages in the most productive year: likely, the reason lies in the supposed low genetic diversity of commercial lentil lines in Italy. We encourage further research, taking into account the diversity of Italian lentil landraces, in order to gain a broader genetic base for the implementation of a trait-based approach, which may lead to better-performing mixtures

Designing cover crop mixtures to enhance potential weed suppression in organic no-till vegetable systems.

Introduction No-tillage in vegetable systems can provide several benefits, but it can only be implemented if there is a powerful strategy to control weeds (Morse, 1999). Cover crops are an essential part of an integrated weed management strategy in no-till organic and low input vegetable systems (Altieri et al., 2011). However, few studies focus on no-tillage practices in organic vegetable systems in European environments, particularly in Mediterranean contexts (Isik et al., 2009). Cover crop effectiveness in weed control, depend on crop traits linked with weed suppressive ability. Mixtures have been used to improve effectiveness of cover crops (Wortman et al., 2012; Smith et al., 2014, Finney et al., 2016). Nonetheless, to our knowledge, this is the first study adopting a functional approach to the design of cover crop mixtures. Our objective was to investigate the effect of functional diversity and composition of cover crops in controlling weeds before transplanting aubergine (Solanum melongena L.), highlighting the relationship between functional traits and weed suppression. Materials and Methods A field trial was performed in an organic field located at CIRAA, University of Pisa, Italy, using a randomized complete block design with 3 replicates and 18 treatments. We selected 8 cover crop species clustered into 4 functional groups as follows: i) large seeded legumes (Pisum sativum L., Vicia sativa L.) characterized by a major development in height; ii) small seeded legumes (Trifolium incarnatum L., T. squarrosum L.) that tend to rapidly cover the soil; iii) grasses (Hordeum vulgare L., Avena sativa L.) characterized by a strong competitive ability and iv) crucifers (Raphanus sativus L., Brassica nigra L.) with allelopathic potential. We designed the mixtures to create a gradient of functional diversity. We included 8 monocrop treatments, 4 two-species mixtures; 4 four-species mixtures including co-presence of 2, 3 and 4 functional groups; an eight-species mixture characterized by the highest level of species and functional diversity, and a no cover crop control. Cover crop plots (3 × 12 m) were broadcast on 27th October 2014 and devitalized on 6th May 2015 with a roller crimper followed by flame weeding. Throughout the experiment, density and height of component cover crop species was regularly recorded. Organically certified aubergine plants (cv “Dalia F1”) were transplanted 5 days after cover crop devitalization. Before devitalization, three above-ground biomass samples of 0.5 m2 per plot were collected. We separated cover crop from weed biomass, and cover crop biomass in the mixtures was further partitioned into component species. Results and Discussion We found no strong correlation between cover crop height and biomass at the time of devitalization. Instead, we found a significant negative relationship between cover crop biomass and weed biomass. This relationship was significantly influenced by treatments. The highest weed biomass was recorded for vetch, although it was significantly lower than in the control. The effect of cover crop biomass on weeds was significant for the small seeded legumes and for pea within the large seeded legumes functional group. We found no significant effect for vetch, as its development was particularly low due to poor establishment in 2014. As for grasses, the effect of cover crop biomass over weeds was not significant. In this functional group, alternative mechanisms, such as allelopathy, might have overcome the biomass effect on weeds. A clear functional differentiation between cover crop species emerges. Conclusions Cover crop mixtures showed a strong potential for weed infestation reduction, given the high amount of biomass produced (Teasdale & Abdul-Baki, 1998). As pointed out by previous research (Mirsky et al., 2013; Mohler & Teasdale 1993), a high quantity of cover crop biomass will ensure good weed suppression during subsequent cash crop cultivation. However, choice and combination of different cover crop functional groups can provide a stronger effect on weeds suppression, through mechanisms not necessarily related to higher biomass production. Our results show that functional characterization of cover crop species and the use of mixtures can be powerful tools in an integrated weed management strategy in organic or low input no-till vegetable systems

Soil arthropod diversity in organic, integrated and conventional olive orchards in Crete

Soil fauna biodiversity and its functional counterpart were monitored in 24 olive orchards under conventional, organic and integrated management located in eight different locations for a year in Messara valley, in southern Crete. In each location three neighbouring orchards under different management were monitored. Pitfall traps were used as trapping method and fixed data collection points were used in each olive orchard for arthropod fauna monitoring. Counter groups of functional taxa were defined, with respect to services of biological pest control and of nutrient cycling in the olive agroecosystem, Monitoring took place weekly for 5 weeks per season, all year around. Comparison of the different management systems in terms of abundance and diversity of soil arthropods and functional groups was performed. Formicidae, Coleopteran family of Tenebrionidae, Araneae, Colembola and Opiliones were the most abundant taxa found in the olive orchards. A trend of higher total abundance and richness was found in the organic olive orchards, however not statistically significant. Functional arthropod abundance followed a similar trend. Diversity indices did not show a constant pattern in terms of management system comparison; however a trend of higher diversity appeared in the less-intensified organic orchards

Exploiting Plant Functional Diversity in Durum Wheat???Lentil Relay Intercropping to Stabilize Crop Yields under Contrasting Climatic Conditions

Relay intercropping is considered a valuable agroecological practice to increase and stabilize crop yields while ensuring the provision of several ecosystem services as well as sustainability and resilience to changing climatic conditions. However, farmers are still reluctant in the use of intercropping practices since there is a huge knowledge gap regarding the time of sowing, sowing ratio, crop stand density, and cultivar choice. In this study, we carried out a 3-year field experiment in Central Italy to assess the effect of relay intercropping on the agronomic performance and competitiveness of winter durum wheat (Triticum durum Desf. cv. Minosse) and spring lentil (Lens culinaris Medik. cv. Elsa) under a low-input management system, comparing different crop stand types (monocrop vs. intercrop) and target plant densities (350 plants m2—full dose vs. 116 plants m2—1/3 dose). The results revealed that intercropping increased grain yield compared to monocropping: significantly (p < 0.0001) against both monocrops in 2021 and non-significantly against durum wheat in 2019 and 2020. Yield advantage in both intercropping systems ranged between 164 and 648%. Durum wheat competitiveness was stronger in 2019 and 2021, while lentil was the most competitive component in 2020. Intercropping favored P accumulation in durum wheat shoots. There was no difference in grain yield of both crops between the highly- and lowly-dense system in 2020 and 2021. Both intercropping strategies were as effective as mechanical hoeing in controlling weeds and proved beneficial in stabilizing lentil productivity. Further economic analysis capturing the additional costs incurred in intercropping and mechanical weeding would highlight the magnitude of profitability of these systems

Changes in Knowledge Management Strategies Can Support Emerging Innovative Actors in Organic Agriculture: The Case of Participatory Plant Breeding in Europe

The “transfer of technology”, typical of a top-down linear process of innovation cannot be used in the new contexts of sustainability, characterised by uncertainty and complexity. There is a need to redefine categories and concepts around which innovation and agricultural policies are built, as those currently in use provide only a partial representation of reality. Innovation paradigms underpinning technological development and public policies design will have a direct impact on decisions regarding which agricultural models will ultimately be supported. Looking at local learning capacity and systems of relations can help to understand the potential to develop innovation within a specific context. This work contributes to the definition of new actors who are developing innovation for sustainability in rural areas. The study focuses on the knowledge systems of farmers who are applying alternative breeding strategies: it uses a network approach to explore the knowledge system in which individual farmers are embedded in order to understand their specific relational features. Three main conclusions emerge from the study: for enhancing the agro-ecological innovation paradigm there is a need to define the ‘innovation broker’, to revise the evaluation system of public research and to integrate innovation and agricultural policies

The significance of mycorrhizal fungi for crop productivity and ecosystem sustainability in organic farming systems

Mycorrhizal fungi are widespread in agricultural systems and are especially relevant for organic agriculture because they can act as natural fertilisers, enhancing plant yield. Here we explore the various roles that mycorrhizal fungi play in sustainable farming systems with special emphasis on their contribution to crop productivity and ecosystem functioning. We review the literature and provide a number of mechanisms and processes by which mycorrhizal fungi can contribute to crop productivity and ecosystem sustainability. We then present novel results, showing that mycorrhizal fungi can be used to suppress several problematic agricultural weeds. Our results highlight the significance of mycorrhizal fungi for sustainable farming systems and point to the need to develop farming systems in which the positive effect of these beneficial soil fungi is optimally being utilized

Communication and the Pragmatic Condition

Presented March 9, 201

Can weed management in vegetable systems be improved by cover crop species mixtures? Step 2: field implementation

Cover crops are a fundamental tool for weed control, especially in organic and low input farming. Species with different functional traits can be combined in mixtures to enhance weed suppression. Our aim was to test the relative importance of functional diversity and functional composition (i.e. complementarity) in improving and stabilising the agroecosystem services expected from cover crops. Following a preliminary screening on cover crop functional traits (Step 1), we identified 8 species belonging to 4 functional groups: large seeded legumes, characterized by higher height (Pisum sativum L., Vicia sativa L.), small seeded legumes, able to cover quickly the soil (Trifolium incarnatum L., T. squarrosum L.), highly competitive grasses (Hordeum vulgare L., Avena sativa L.) and allelopathic brassicas (Raphanus sativus L., Brassica nigra L.). We designed 4 two-species mixtures, 4 four-species mixtures and 1 eighth-species mixtures and set a gradient of diversity: (i) pure stands; (ii) co-presence of 2 functional groups; (iii) diversity within 2 co-occurring functional groups, (iv) co-presence of 4 functional groups, (v) diversity within 4 co-occurring functional groups. The trial was conducted in an organic field located in Pisa, Italy. Experimental plots were seeded on 27 October 2014 following a randomized complete block design with three replicates, and devitalized on 6 May 2015. Weed biomass was significantly lower in mixtures with the higher level of diversity compared to the unweeded control (from -87% up to -97%). Cover crop mixtures proved to e more productive than pure stands, since Land Equivalent Ratio was >1 in all but one mixture. For some species, biomass production was higher in high diversity mixtures compared to pure stands. Functional diversity in cover crops can play a key role on biomass productivity and weed suppression. Data will be analysed to clarify the role of functional composition on cover crops agroecosystem services provision