Impact of the Legume Catch Crop Serradella on Subsequent Growth and P Mobilization under Barley in Different Fertilization Treatments

Legume catch crops can enhance soil fertility and promote the N and P supply of the subsequent main crop, especially with low mineral fertilizer use. However, the specific impact of catch crops on arbuscular mycorrhiza formation of the following main crop is unknown. Therefore, the impact of serradella (Ornithopus sativus) vs. bare fallow was tested on mycorrhiza formation, potential soil enzyme activities and plant-available P under subsequently grown barley (Hordeum vulgare) and different fertilization treatments (P-unfertilized—P0; triple superphosphate—TSP; compost—COM; combined—COM + TSP) in a long-term field experiment in northeastern Germany. Catch cropping significantly increased mycorrhiza formation of barley up to 14% compared to bare fallow. The impact of serradella on mycorrhiza formation exceeded that of the fertilization treatment. Serradella led to increased phosphodiesterase activities and decreased ß-glucosidase activities in soil. Plant availability of P was not significantly affected by serradella. These findings provide initial evidence that even serradella as a non-host crop of mycorrhizal fungi can promote the mycorrhiza formation of the subsequent crop and P mobilization in soil. We conclude that the prolonged vegetation cover of arable soils by the use of catch crops can promote P mobilization and transfer from P pools to the following main crops.

Mycorrhiza Formation in Pinus Sylvestris and Picea Obovata Seedlings in Forest Nurseries in Kazakhstan

This work presents research materials, the purpose of which is to grow seedlings of coniferous trees in the open field using artificial substrates of mycorrhizal macromycetes in forest nurseries of Central, North and Northeast Kazakhstan. The success of mycorrhiza formation in seedlings Pinus sylvestris and Picea obovata from forest nurseries of Akmola and Karaganda regions, and the survival rate of seedlings from forest nurseries of Akmola, Karaganda and Pavlodar regions of Kazakhstan are analysed. In the future, we want to expand the range of studied species and compare artificially mycorrhized seedlings with naturally mycorrhized species from natural forests. If we compare the survival rate of seedlings in nurseries, the highest in P. sylvestris seedlings in Shaldai is about 78%, low in Novodolenskoe, about 27%, and for P. obovata, on average, 66%. In the future, we want to expand the range of studied species and compare artificially mycorrhized seedlings with naturally mycorrhized species from natural forests.

Platanthera bifolia (L.) Rich. on industrial dumps in the Middle Urals

We studied cenopopulations of Platanthera bifolia on industrial dumps in the Middle Urals (the southerndump of the Veselovsky brown coal deposit, the ash dump of the Verkhnetagil State District Power Plant). The spatial,age, morphological structure and features of mycorrhiza formation of this species on disturbed lands were studied. Thecenopopulations of P. bifolia growing on industrial dumps of the Veselovsky brown coal deposit, VSDPP ash dump andin the natural forest phytocenosis of the forest park are normal, incomplete, with a predominant generative state in theage spectrum. It was revealed, that P. bifolia individuals from industrial dumps correspond to the sizes of individualsfrom natural habitats according to most biometric indicators. The size of the root system is significantly affected by thecharacteristics of the substrate (low fertility, rockiness).

Nodule Inception Is Not Required for Arbuscular Mycorrhizal Colonization of Medicago truncatula

Most legumes can engage in symbiosis with N-fixing bacteria called rhizobia. This symbiosis, called nodulation, evolved from the more widespread symbiosis that most land plants form with arbuscular mycorrhiza, which is reflected in a common requirement of certain genes for both these symbioses. One key nodulation gene, Nodule Inception (NIN), has been intensively studied. Mutants in NIN are unable to form nodules, which has made it difficult to identify downstream genes under the control of NIN. The analysis of data from our recent transcriptomics study revealed that some genes with an altered expression of nin during nodulation are upregulated in mycorrhizal roots. In addition, another study reported the decreased colonization of nin roots by arbuscular mycorrhiza. We therefore investigated a role for NIN in mycorrhiza formation. Our time course study, using two nin alleles with differing genetic backgrounds, suggests that that loss of NIN does not affect colonization of Medicago truncatula roots, either in the presence or absence of rhizobia. This, and recent phylogenetic analyses showing that the loss of NIN is correlated with loss of nodulation in the FaFaCuRo clade, but not with the ability to form mycorrhiza, argue against NIN being required for arbuscular mycorrhization in legumes.