Digital Theses Archive


Tesi etd-03312021-092055

Type of thesis
Legume selection for living mulches in Mediterranean integrated weed management cropping systems
Scientific disciplinary sector
  • Nessuna parola chiave trovata
Exam session start date
Legume selection for living mulches in Mediterranean integrated weed management cropping systems<br><br>Abstract<br><br>In order to support the application of IWM practices based on crop diversification we investigated the agronomical performance of several legume species and ecotypes to select the most suitable ones as living mulch in cereal and vegetable cropping systems. The establishment of a legume living mulch is one of the most well-known practices for a more sustainable and effective weed control, however, it is not widely practiced because often it fails to meet performance expectations of farmers. In fact, the use of a legume living mulch is a high knowledge-intense cropping practice and farmers needs to be supported for a successful establishment and management of the living mulch. In particular, the lack of knowledge on suitable legume species for specific cropping systems and environmental conditions has been identified as the main bottleneck for the successful application of living mulches and increased uptake of this practices at farm level. Therefore, legumes with specific morphological and phenological characteristics need to be identified to support the use of legume living mulches as effective and sustainable tool in IWM systems. <br>Growth characteristics and weed suppression ability have been largely investigated for the most common legumes sole crop, however their performance as living much is still not well studied. For this purpose, more than 30 different legumes among commercial cultivars and ecotypes were evaluated in this project and tested for two target cropping systems:<br>• Cereal-based Mediterranean cropping systems. We evaluated the suitability of legumes for relay intercropping with durum wheat under different environmental conditions and cropping system management types and evaluated residual effects of legumes on the subsequent crop. An in-depth study on the potential plant-plant interactions between the two intercrops was performed in a laboratory trial. <br>• Organic and conservative vegetable cropping systems. We evaluated many legume species and ecotypes as sole crop and identified the most suitable ones to be potentially used as permanent living mulch in organic and conservative vegetable cropping systems.<br><br>The thesis consists of four scientific chapters, beside the general introduction and the overall discussion and conclusions.<br><br>Chapter 1: Relay Intercropping can Efficiently Support Weed Management in Cereal-Based Cropping System when Appropriate Legume Species are Chosen.<br>Objectives: This study aims to evaluate the suitability of 12 different legumes for relay intercropping with durum wheat, among perennial, annual and annual self-seeding species under different crop management systems (a low-input system and an integrated system) and with different sowing technique.<br>Hypothesis: According to the input level of the cropping system, we hypothesized a different behavior and role in the target cropping system for perennial, annual and annual self-seeding legumes. As well, we hypothesized an effect on legume establishment based on the sowing method used.<br>Main results: i) Undersown legumes have no negative impact on grain yield, ii) drill sowing of legumes in the wheat inter-row space guarantees a better establishment of the living mulches, iii) Only perennial legumes such as Medicago sativa, Trifolium repens and Medicago lupulina showed suitable characteristics to be used for relay intercropping systems with durum wheat at the high productivity potential site as Ravenna (integrated system), iv) Perennial (Medicago sativa, Hedysarum coronarium) and annual self-seeding legumes (Trifolium subterraneum) seem the best options for low-input systems as in Pisa.<br><br>Chapter 2: Legume relay intercropping affects crop production, N uptake and weed control of the associated wheat and the subsequent sorghum crop.<br>Objectives: We evaluated, performance of eight undersown legumes among perennial, annual and annual self-seeding species on their contribution in N and weed control to the associated durum wheat and subsequent sorghum.<br>Hypothesis: We hypothesized that legume species can have a different suitability for use in relay intercropping systems due to specific morphological and phenological characteristics. It has been reported that different legume species as sole crop do not have the same efficiency in controlling weeds and not all legumes show the same degree of contribution to the subsequent cash crop. Their behaviour in relay intercropping systems remain not well studied.<br>Main results: i) undersown legumes do not affect N uptake and grain protein content on wheat, ii) Perennial legumes were identified as the most suitable legume species to be used in relay intercropping with durum wheat in a cropping system environment where water is not a limiting factor during the summer, whereas annual self-seeding such as T. subterraneum can be a viable alternative in areas characterised by dry summer, iii) H. coronarium, M. sativa, T. repens, M. lupulina and T. subterraneum had highest weed capacity during the intercropping period and in the subsequent spring, iv) H. coronarium, M. sativa and T. subterraneum significantly support biomass production and N uptake of the subsequent sorghum, v) residual effects of legumes on weeds in subsequent sorghum. <br><br>Chapter 3: LC-MS/MS Analysis of Several Legume Species Reveal an Increase in the Production and Root Exudation of Flavonoids as Response to Intercropping<br>Objectives: This study aims to investigate how the concentration of flavonoids alters in plant tissues and root exudates of four legume species in response to the co-cultivation with durum wheat.<br>Hypothesis: We hypothesized that flavonoids increase in legume shoot and root and in root exudates in response to co-cultivation with wheat. In addition, we hypothesized that legumes have specific flavonoid profiles and that the characterization of legumes on basis of the flavonoid profiles can be an additional parameter to be considered for the evaluation of suitable legumes for living mulch systems.<br>Main results: i) The interspecific competition with wheat negatively affected the legume growth and leads to a significant reduction of shoot (-60%) and root biomass (-37%) in comparison with legume grown in monoculture, ii) The concentration of flavonoids significantly increase by 335% and 176%, respectively, in legumes shoot and root biomass, iii) concentrations of daidzein, genistein, medicarpin, formononetin and kaempferol significantly increase in plant tissue and root exudates of legumes in response to their co-cultivation with wheat.<br><br>Chapter 4: Legume Ecotypes and Commercial Cultivars Differ in Performance and Potential Suitability for Use as Permanent Living Mulch in Mediterranean Vegetable Systems.<br>Objectives: We investigated weed control capacity and variability in morphological and phenological traits relevant in inter-plant competition among a range of 11 commercial cultivars of legumes and seven ecotypes. The objective of this study is the characterization of a range of promising commercial cultivars and ecotypes of perennial and annual self-seeding legumes for their use as pLM in Mediterranean vegetable systems.<br>Hypothesis: We hypothesize that legumes characterized by a high biomass production and a fast and complete soil coverage can have a good weed control capacity. Moreover, since pLM systems involve the persistence of legumes for more than one growing season, we expected that legumes able to maintain such a characteristic over time can be particularly suitable for this system. Additionally, for annual self-seeding legumes, high self-seeding capacity is an important factor for their persistence in time. According to the literature, we hypothesize also that legume canopy height is an important factor determining above ground competition between legumes and the main crop and for this reason, it should be considered in the screening process.<br>Main results: i) Lotus corniculatus and Trifolium repens showed the best weed control capacity over time, ii) while Trifolium subterraneum and Medicago polymorpha had more suitable characteristics for a rapid and complete establishment of the permanent living mulch, iii) Legume mulches appear more effective in dicotyledonous than in monocotyledonous weed control.<br>