Publicação
Chickpea (Cicer arietinum L.) inoculation with beneficial microorganisms for increased productivity and resilience under a changing environment
| Resumo: | Development of sustainable and competitive legume based agricultural systems is at the core of agricultural policies in Europe. A significant driver of which, is the urgent need to improve the European Union’s autonomy in plant-based protein and the acknowledgement of legumes key role to sustainable cropping systems. However, climate projections show a variability of precipitation (in time, space and intensity), warmer temperatures and increased of likelihood drought events, that together with the global water scarcity crises constitute challenging factors that threaten legume production. Chickpea is a widely cropped grain legume recognized as an important source of proteins for humans. It is mostly cultivated in areas where terminal drought stress, poor soil fertility and limited use of chemical fertilizers are already frequent and overlapping problems that compromise plant growth and productivity. The overall objective of this thesis is to contribute to increase the productivity and resilience of chickpea under climate change conditions, by focusing on smart agriculture practices such suitability of the growing season and genotypes, irrigation management strategies and application of biofertilizers based on microbial inoculants. In addition, the goal is to gain a deeper insight into the beneficial microorganisms associated with chickpea roots and seeds by exploring their biological mechanisms and understanding their phylogenetic relationships. In that regard, a field trial was carried out during 2016 and 2017 to investigate the effects of autumn and spring sowing on yield and seed crude protein content of 11 chickpea genotypes. Results revealed that the longer growing period of plants sown in autumn affected positively plant growth parameters. In the majority of the genotypes, grain yield was higher in autumn sowing, comparatively with spring sowing. Within the Kabuli type, the genotype CHK 3357 presented the highest grain yield in both growing seasons, while in the Desi type it was the genotype India. Seed crude protein content was significantly higher in spring sowing over autumn sowing. These data further contribute to understand the effect of the growing season on chickpea production and to encourage the switch from traditional spring to autumn sowing, in regions where drought and heat stress are two major constraints that limit yield. To develop a new perspective on plant growth promoting bacteria (PGPB) associated with chickpea several procedures were undertaken involving the isolation of microsymbionts from roots. Bacterial strains were tested regarding their plant growth promotion characteristics, and the most promising strains were selected to be used in microbial based formulations. The phylogenetic relationships and taxonomic affiliation was performed in a multilocus sequence analysis. Results show that the majority of the isolates possess two or more plant growth promoting mechanisms, being phosphate solubilization and IAA production the most common traits. The analysis of the 16S rDNA gene showed isolates belonging to the Agrobacterium, Rhizobium, Mesorhizbium, and Burkholderia and Paraburkholderia genus. Moreover, phylogenetic incongruence between 16S rDNA based phylogeny and phylogenies based on symbiosis genes (nodA and nodC) indicated evidence of lateral transfer of symbiosis genes across different species. Chickpea is nodulated by different species with common symbiosis genes, which may suggest that the plant only recognize a few Nod factors. To deepen the study, a field trial was carried out with two chickpea genotypes to understand how the selected microbial inoculants influence plant performance under different irrigation regimes. Inoculation with PGPB had beneficial effects on plant performance and grain yield regardless the irrigation level, however, co-inoculation with PGPB and arbuscular mycorrhizal fungi (AMF) shows a far greater potential to improve productivity. The observed differences also showed the importance of irrigation compared to complete absence of irrigation. Plants irrigated only during the critical growth stages of flowering and pod filling showed higher grain yields when compared to plants from other water deficit treatments and even without water stress. Finally, culturable endophytic bacterial communities from chickpea seeds were isolated, identified and characterized to better understand their diversity and functionality. Seeds harbour highly diverse endophytic communities exhibiting multiple functional traits that may have important impacts on plant growth, health and productivity. However, their role in shaping plant microbiome and mode of transmission to the next generation through seeds is not completely clear. Bacterial strains encountered were assigned to the phyla Proteobacteria, Actinobacteria and Firmicutes, with Bacillus being the dominant genera. The novelty of this study is the presence of the rhizobial bacteria Burkholderia and Mesorhizobium in seed microbiome, suggesting vertical transmission of bacterial endophytes from seed to reproductive organs within the plants. Vertical transmission of species-specific bacterial communities’ fits well with the emerging view that recruitment, modulation and employment of the microbial component of the plant holobiont is a strategy to adapt agriculture production to a changing environment. Therefore, development of microbial inoculants from plant core microbiota has potential to increase the efficiency of bio fertilizers and increase sustainable production. |
|---|---|
| Autores principais: | Laranjeira, Sara Silva |
| Assunto: | Cicer arietinum L. productivity growing season PGPB AMF biological mechanisms biofertilizers drought inoculation water management protein phylogeny |
| Ano: | 2022 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso restrito |
| Instituição associada: | Universidade de Trás-os-Montes e Alto Douro |
| Idioma: | inglês |
| Origem: | Repositório da UTAD |
| Resumo: | Development of sustainable and competitive legume based agricultural systems is at the core of agricultural policies in Europe. A significant driver of which, is the urgent need to improve the European Union’s autonomy in plant-based protein and the acknowledgement of legumes key role to sustainable cropping systems. However, climate projections show a variability of precipitation (in time, space and intensity), warmer temperatures and increased of likelihood drought events, that together with the global water scarcity crises constitute challenging factors that threaten legume production. Chickpea is a widely cropped grain legume recognized as an important source of proteins for humans. It is mostly cultivated in areas where terminal drought stress, poor soil fertility and limited use of chemical fertilizers are already frequent and overlapping problems that compromise plant growth and productivity. The overall objective of this thesis is to contribute to increase the productivity and resilience of chickpea under climate change conditions, by focusing on smart agriculture practices such suitability of the growing season and genotypes, irrigation management strategies and application of biofertilizers based on microbial inoculants. In addition, the goal is to gain a deeper insight into the beneficial microorganisms associated with chickpea roots and seeds by exploring their biological mechanisms and understanding their phylogenetic relationships. In that regard, a field trial was carried out during 2016 and 2017 to investigate the effects of autumn and spring sowing on yield and seed crude protein content of 11 chickpea genotypes. Results revealed that the longer growing period of plants sown in autumn affected positively plant growth parameters. In the majority of the genotypes, grain yield was higher in autumn sowing, comparatively with spring sowing. Within the Kabuli type, the genotype CHK 3357 presented the highest grain yield in both growing seasons, while in the Desi type it was the genotype India. Seed crude protein content was significantly higher in spring sowing over autumn sowing. These data further contribute to understand the effect of the growing season on chickpea production and to encourage the switch from traditional spring to autumn sowing, in regions where drought and heat stress are two major constraints that limit yield. To develop a new perspective on plant growth promoting bacteria (PGPB) associated with chickpea several procedures were undertaken involving the isolation of microsymbionts from roots. Bacterial strains were tested regarding their plant growth promotion characteristics, and the most promising strains were selected to be used in microbial based formulations. The phylogenetic relationships and taxonomic affiliation was performed in a multilocus sequence analysis. Results show that the majority of the isolates possess two or more plant growth promoting mechanisms, being phosphate solubilization and IAA production the most common traits. The analysis of the 16S rDNA gene showed isolates belonging to the Agrobacterium, Rhizobium, Mesorhizbium, and Burkholderia and Paraburkholderia genus. Moreover, phylogenetic incongruence between 16S rDNA based phylogeny and phylogenies based on symbiosis genes (nodA and nodC) indicated evidence of lateral transfer of symbiosis genes across different species. Chickpea is nodulated by different species with common symbiosis genes, which may suggest that the plant only recognize a few Nod factors. To deepen the study, a field trial was carried out with two chickpea genotypes to understand how the selected microbial inoculants influence plant performance under different irrigation regimes. Inoculation with PGPB had beneficial effects on plant performance and grain yield regardless the irrigation level, however, co-inoculation with PGPB and arbuscular mycorrhizal fungi (AMF) shows a far greater potential to improve productivity. The observed differences also showed the importance of irrigation compared to complete absence of irrigation. Plants irrigated only during the critical growth stages of flowering and pod filling showed higher grain yields when compared to plants from other water deficit treatments and even without water stress. Finally, culturable endophytic bacterial communities from chickpea seeds were isolated, identified and characterized to better understand their diversity and functionality. Seeds harbour highly diverse endophytic communities exhibiting multiple functional traits that may have important impacts on plant growth, health and productivity. However, their role in shaping plant microbiome and mode of transmission to the next generation through seeds is not completely clear. Bacterial strains encountered were assigned to the phyla Proteobacteria, Actinobacteria and Firmicutes, with Bacillus being the dominant genera. The novelty of this study is the presence of the rhizobial bacteria Burkholderia and Mesorhizobium in seed microbiome, suggesting vertical transmission of bacterial endophytes from seed to reproductive organs within the plants. Vertical transmission of species-specific bacterial communities’ fits well with the emerging view that recruitment, modulation and employment of the microbial component of the plant holobiont is a strategy to adapt agriculture production to a changing environment. Therefore, development of microbial inoculants from plant core microbiota has potential to increase the efficiency of bio fertilizers and increase sustainable production. |
|---|