The new products obtained from natural resources are an alternative to methods based on traditional mineral fertilizers, which are destructive for soil mycorrhizal communities. Our experiment was carried out to evaluate the effect of organic fertilizers and amendments of very diverse composition on mycorrhizal abundance and diversity, as well as on root growth, in strawberry plants cv. “Honeoye”. The plants were grown in rhizoboxes filled with a podsolic soil. The plants were treated with granulated bovine manure, vermicompost extract, humates extract, plant extract, extract from seaweed species reinforced with humic and fulvic acids, a consortium of beneficial soil organisms, a stillage from yeast production and a solution of titanium. Plants treated with products and the microorganisms consortium also received half dose of manure. A standard mineral fertilization (NPK) and an unfertilized control were also included. The bioproducts based on humus-like substances and the yeast stillage had the greatest positive influence on the colonization of roots by arbuscular mycorrhizal fungi (AMF). The different treatments affected the diversity of AMF species present in the rhizospheric soil. All organic products, even though providing a significantly low amount of nutrients, enhanced root growth characteristics in comparison to the mineral fertilization.
The utilisation of products of organic origin in agriculture, especially fertilizers and soil amendments, has increased in the last years. The search for new resources of organic fertilizers for a modern environment-friendly agriculture, including organic farming, derives from the limited availability of traditional ones, such as manure. There is also the need for limitation of use of synthetic fertilizers, which have been found to induce disturbance to soil characteristics (acidification, degradation of soil biota) [
Arbuscular mycorrhizal fungi belonging to the phylum Glomeromycota are the most widespread group of symbiotic fungi, with 80% of land plants forming AMF symbiosis [
AMF can play an important role in compensating for reduced use of chemical fertilisers and improving soil nutrients utilization in organic agriculture or other low-input agricultural systems [
The experiment was carried out in a greenhouse over a 5-month period with the use of frigo-plants of the strawberry cultivar “Honeoye”. The plants were planted in rhizoboxes (37 × 1.8 × 20 cm), filled with 1.85 kg of a podsolic soil collected from an uncultivated field of an experimental organic orchard of the RIH. Five rhizoboxes, each containing two plants, were used as replications for each treatment. The plants were subjected to the following growing conditions: photoperiod 16/8 h (day/night), light intensity 70 µM∙m−2s−1, temperature 25/20˚C and air humidity approx. 50% [
The following experimental treatments were applied:
1) Control (no-treatment).
Soil fertilizers:
2) Mineral fertilizer (NPK): 1.02 g NH4NO3; 1.9 g triple superphosphate and 1.16 g K2SO4 per rhizobox.
3) Dry granulated bovine manure soil fertilization (Manure) (Doktor O’grodnik)?1 g per rhizobox.
4) A mixture of AM fungi: Glomus species, Trichoderma viride and rhizosphere bacteria species (Bacillus subtilis, Pseudomonas fluorescens, Streptomyces spp.) (Micosat) (CCS Aosta s.r.l.)?10 g per rhizobox.
5) An extract from a vermicompost (Humus UP) (Ekodarpol)?25 ml 2% solution per rhizobox distributed 3 times.
6) A soil improver with humates (Humus Active) (Ekodarpol)?20 ml 2% solution of Humus Active and 5 ml 1% solution of Aktywit PM per rhizobox distributed 3 times.
Foliar fertilizers:
7) A seaweeds extract reinforced with humic and fulvic acids (BF Quality) (Agrobio Products B.V.)?25 ml 0.5% solution sprayed to the leaves three times + 0.5 g manure to the soil per rhizobox.
8) A plant extract enriched in amino-acids (BF Amin) (Agrobio Products B.V.)?25 ml 0.5% solution sprayed to the leaves three times + 0.5 g manure to the soil per rhizobox.
9) Titanium (Ti) 0.8% (Tytanit) (Intermag)?25 ml 0.05% solution sprayed to the leaves three times + 1 g manure to the soil per rhizobox.
10) A stillage from bakery yeasts production (Vinassa) (Lallemand Polska)?25 ml 0.5% solution sprayed to the leaves three times + 0.5 g manure to the soil per rhizobox. The amount of the nutrient macroelements provided with each treatment is presented in
In order to asses mycorrhizal frequency, strawberry roots were collected at the end of the growing period (five months after inoculation) and cold-stained using the Phillips and Hayman method [
The microscopic analysis of the roots was carried out according to Trouvelot’s method [
For each experimental treatment three replicates were analyzed, constituting in total 90 root segments.
In order to identify the species of arbuscular mycorrhizal fungi present in the rhizospheric soil of strawberries, trap cultures were set up with narrowleaf plantain (Plantago lanceolata L.). The plants were planted in 0.5 l pots (3 repetitions per treatment) filled with a mixture of strawberry rhizosphere soil and autoclaved sand, at a ratio of 1:1 v/v [
Treatments | N | P | K |
---|---|---|---|
Control | 0.0 | 0.0 | 0.0 |
NPK | 70 | 26 | 100 |
Manure | 45 | 13 | 17 |
Micosat | 23 | 6.5 | 12 |
Humus UP | 1 | 0.1 | 0.2 |
Humus Active | 0.5 | 0.1 | 2 |
BF Quality | 23 | 6.5 | 8.5 |
BF Amin | 23 | 6.5 | 8.5 |
Tytanit | 45 | 13 | 17 |
Vinassa | 23 | 6.5 | 8.5 |
the number and thickness of layers of spore walls [
At the end of the growth period, strawberry root dry weight was determined in accordance with the analytical procedure developed by Ostrowska et al. [
The results were statistically evaluated by analysis of variance. Comparisons of means were done at p £ 0.05 with the Duncan test. To compare the genetic diversity of mycorhizal species (mycorrhizal population numbers), the Shannon and derivative Equitability indexes were calculated using the PAST program. Pairwise correlations between mycorrhizal Frequency (F%), Shannon index diversity, root growth and morphological parameters of strawberry plants were carried out using non-parametric Spearman rank statistics testing at p < 0.05.
A Principal Component Analysis (PCA) was carried out on the mean number of spores per sample occurring in the roots of strawberry plants grown in rhizoboxes, treated with the mineral fertilizer (NPK) and the different soil and foliar fertilizers with the aim to identify relationships among the treatments and the abundance of spores. A PCA was carried out also considering the amount of nutrient elements provided with the different treatments, mycorrhizal frequency, diversity index (H’) and morphological root parameters with the aim to identify latent relationships among them. These analyses were performed with SPSS statistics (version 21, IBM corporation).
The highest value of mycorrhizal frequency (F%) was obtained for the treatment with the humate-based product (Humus Active: 38.89), followed by the vermicompost extract (Humus UP: 31.11), the yeast stillage (Vinassa: 29.21) and the microorganisms consortium (Micosat: 26.67) (
Treatments | F [%] | M [%] | m [%] |
---|---|---|---|
Control | 12.22 b | 0.26 a | 2.00 a |
NPK | 5.56 a | 0.06 a | 1.00 a |
Manure | 7.78 ab | 0.08 a | 1.00 a |
Micosat | 26.67 c | 1.49 a | 6.05 a |
Humus UP | 31.11 d | 3.52 a | 6.35 a |
Humus Active | 38.89 e | 0.57 a | 1.46 a |
BF Quality | 8.89 ab | 0.82 a | 8.11 a |
BF Amin | 13.33 b | 0.82 a | 3.95 a |
Tytanit | 2.22 a | 0.02 a | 0.67 a |
Vinassa | 29.21 cd | 2.44 a | 8.20 a |
of mycorrhizal intensity (m%) (8.20), similar to the plant extract (BF Quality: 8.11), Humus UP (6.35), and Micosat (6.05). The lowest values of mycorrhizal frequency and intensity were obtained after the treatment with Tytanit and in the NPK control (
The highest number of species of AM fungi was found in the treatment with manure (4 species), followed by the treatments with Humus Active, Tytanit and Vinassa (3 species) (
The production of spores in rhizospheric soil was statistically different only in the treatment with Humus Active (
The diversity index H resulted with a value higher than 1 for the control and the treatments with soil fertilizers, except manure alone which showed a value lower than 1 (
The two first components of the PCA on the effect of the different treatments on the number of spores resulted in a more than 70% description of the total variance (
Treatments | Species |
---|---|
Control | Claroideoglomus claroideum Rhizophagus fasciculatus |
NPK | Claroideoglomus claroideum Rhizophagus fasciculatus |
Manure | Claroideoglomus claroideum Funneliformis mosseae Funneliformis caledonium Scutellospora dipurpurescens |
Micosat | Claroideoglomus claroideum Funneliformis mosseae |
Humus UP | Claroideoglomus claroideum Funneliformis mosseae |
Humus Active | Claroideoglomus claroideum Funneliformis mosseae Rhizophagus fasciculatus |
BF Quality | Claroideoglomus claroideum Funneliformis mosseae |
BF Amin | Claroideoglomus claroideum Funneliformis constrictum |
Tytanit | Claroideoglomus claroideum Funneliformis mosseae Rhizophagus fasciculatus |
Vinassa | Claroideoglomus claroideum Funneliformis mosseae Funneliformis constrictum |
Treatment | Mean number of spores per sample (100 g) |
---|---|
Control | 297.00 a |
NPK | 136.66 a |
Manure | 317.33 a |
Micosat | 308.66 a |
Humus UP | 300.00 a |
Humus Active | 860.33 b |
BF Quality | 451.66 a |
BF Amin | 372.00 a |
Tytanit | 196.33 a |
Vinassa | 216.33 a |
composed of the foliar treatments with organic products (i.e. BF Amin, BF Quality and Vinassa) which grouped closely to the Control and to the soil treatment Humus Active. Two groups were formed by two products each: Tytanit and Manure, Micosat and Humus UP. The mineral fertilizer NPK was separated from all other treatments.
Treatment | H | J | J/H |
---|---|---|---|
Control | 1.001 | 0.9112 | 0.9103 |
NPK | 1.096 | 0.9972 | 0.9099 |
Manure | 0.9271 | 0.8439 | 0.9103 |
Micosat | 1.016 | 0.9246 | 0.9100 |
Humus UP | 1.092 | 0.9944 | 0.9106 |
Humus Active | 1.024 | 0.9318 | 0.9100 |
BF Quality | 1.001 | 0.9107 | 0.9098 |
BF Amin | 0.7906 | 0.7196 | 0.9102 |
Tytanit | 0.9396 | 0.8553 | 0.9103 |
Vinassa | 0.9285 | 0.8452 | 0.9103 |
All organic fertilizers affected the growth and morphology of roots (
Treatments | Rhizosphere pH | Root dry weight [g] | Root surface area [cm2] | Root volume [cm3] | Root length [cm] | Number of root tips | Root branching index |
---|---|---|---|---|---|---|---|
Control | 5.2 a | 2.4 ab | 522 ab | 7.44 ab | 2927 b | 6427 c | 2.2 c |
NPK | 5.8 b | 1.7 a | 466 ab | 7.89 ab | 2869 b | 4758 b | 1.7 a |
Manure | 5.9 b | 2.2 ab | 530 ab | 11.39 b | 3784 c | 6513 c | 1.8 a |
Micosat | 6.2 c | 2.7 b | 728 b | 10.17 b | 3585 c | 7674 cd | 2.1 c |
Humus UP | 5.9 b | 2.8 b | 673 b | 11.17 b | 3622 c | 6870 c | 1.9 b |
Humus Active | 6.3 c | 1.5 a | 707 b | 8.57 ab | 3029 b | 5561 bc | 1.9 b |
BF Quality | 5.9 b | 1.9 ab | 567 ab | 7.47 ab | 2664 b | 6035 bc | 2.3 c |
BF Amin | 6.2 c | 1.2 a | 498 ab | 5.51 a | 1955 a | 3891 a | 2.0 b |
Tytanit | 6.1 c | 2.2 ab | 366 a | 10.56 b | 3923 c | 7991d | 2.1 c |
Vinassa | 6.6 d | 1.6 ab | 721 b | 7.34 ab | 2396 a | 4344 b | 1.8 a |
and in several cases not different from the control Vinassa induced the largest root surface area, while manure, alone or with addition of Tytanit, very positively affected the total length of roots. No differences were found in the diameter of the roots, being after all treatments on average 0.59 mm (data not shown). Interestingly, the highest root branching index was found for Micosat, BF Quality and Tytanit, not different from the control. The other fertilizers induced a lower index in comparison to the control, with NPK, Manure and Vinassa significantly different from all treatments. Both soil and foliar fertilizers significantly increased the pH measured in the rhizosphere zone. The most alkaline values were associated to the treatment with Vinassa (about 1.5 units more); Micosat, Humus Active, BF Amin and Tytanit increased the pH of about 1 point, while the remaining treatments modified less the value (
The PCA evaluating the relations among the nutrients provided by the different treatments and the mycorrhizal and morphological root parameters showed a striking separation of the different parameters (
The treatment of the soil and strawberry plants with products based on very different substances (microbial inocula, seaweed or plants extracts, humic extracts, animal manure) exerted a very diverse effect on AMF inoculation, sporulation, AMF diversity and root growth.
The plants treated with the products containing humic extract (Humus Active, Humus UP) showed a very high colonization ratio (
Application of the seaweed extract (BF Quality) or plant extract (BF Amin) did not give positive effect on total root colonisation by AMF (
The stillage derived from the yeast production (Vinassa) had the greatest positive influence on the colonization of strawberry roots by AMF. The product is rich in yeast cell components, including several aminoacids and other compounds (e.g. betaine) which are released by the yeasts during their growth. Singh et al. [
Fertilization with NPK and Manure significantly reduced mycorrhizal frequency. Use of readily soluble fertilisers, particularly N fertilisers, as well as P fertilizers, has been reported to have a negative impact on AM colonisation and/or diversity in some cases [
Root growth and morphology was strongly affected by the different treatments. The humic extract from vermicompost (Humus UP) and the microbial consortium (Micosat), which were characterized by the lowest content of nutrient elements, induced the highest root growth (
The different products induced modification also of the root system morphology. Two products provided as foliar sprays (i.e. BF Quality and BF Amin) induced a limited development of the root system, similarly to the control or NPK treatment, particularly of the number of root tips (
The treatment with Micosat, a consortium of AMF and other rhizosphere microorganisms, increased the development of roots and root branching (
The effect of titanium, the only nutrient present in the product Tytanit, is mainly related to the increase photosynthetic efficiency [
The correlation found among root diameter, surface area and mycorrhizal frequency (
The number of AM fungal spores recovered from the soil was within the range of spore densities found in other cultivated agricultural soils, both conventionally and organically managed, [
The different treatments affected also the species of mycorrhizal fungi present in the rizhosphere (
The research about influence of bioproducts mentioned above on soil mycorrhizal communities of strawberry plants will be carried out in field conditions.
The influence of the different products on the development of AMF symbiosis in “Honeoye” strawberry plants and on the resulting root development could be related to their chemical and biological characteristics. The bioproducts based on vermicompost extracts (Humus Active and Humus UP) and the yeast stillage (Vinassa) had the greatest positive influence on the colonization of roots by AMF. The different treatments affected the diversity of AMF species present in the rhizospheric soil, which could be considered as an additional feature for assessing the effect on the soil biodiversity due to these agronomical means. Generally, all organic products positively affected root growth characteristics, even in comparison to the standard mineral fertilization (NPK), but some of them (e.g. Humus UP, Vinassa and BF Quality) were on average more efficient than others.
We thank Prof. Janusz Błaszkowski from the West Pomeranian University of Technology in Szczecin for the help in classifying the spores isolated from trap cultures.
The work has been supported by a grant from the EU Regional Development Fund through the Polish Innovation Economy Operational Program, contract No. UDA-POIG.01.03.01-10-109/08-00.
Lidia SasPaszt,EligioMalusá,BeataSumorok,LoredanaCanfora,EdytaDerkowska,SławomirGłuszek, (2015) The Influence of Bioproducts on Mycorrhizal Occurrence and Diversity in the Rhizosphere of Strawberry Plants under Controlled Conditions. Advances in Microbiology,05,40-53. doi: 10.4236/aim.2015.51005