food and energetic needs will thus increase dramatically, while conventional agriculture is, even actually, facing drastic reductions in production yields and/or severe increases in cost to compensate losses in productivity due to lower soil fertility

Castro, Paula M. L.

Marques, Ana P. G. C.

Moreira, Helena

Pereira, Sofia A.

English

Helena Moreira

Sofia A. Pereira

Paula M. L. Castro

Ana P. G. C. Marques

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EFFECTS OF THE INOCULATION WITH SOIL MICROBIOTA ON MAIZE GROWN IN SALINE SOILS

Repositório Institucional da Universidade Católica Portuguesa

EUCARPIA Working Group on Plant Microbe Interaction, June 25 and 26, 2015  EFFECTS OF THE INOCULATION WITH SOIL MICROBIOTA ON MAIZE GROWN IN SALINE SOILS  Helena MOREIRA, Sofia A. PEREIRA, Paula M.L. CASTRO*, Ana P.G.C. MARQUES CBQF – Centro de Biotecnologia e Química Fina, Escola Superior de Biotecnologia, Centro Regional do Porto da Universidade Católica Portuguesa, Rua Dr. António Bernardino Almeida, 4200-072 Porto, Portugal Presenter (*plcastro@porto.ucp.pt)    Introduction According to the UN 2010 predictions, the human population will reach 10 billion by 2080. The food and energetic needs will thus increase dramatically, while conventional agriculture is, even actually, facing drastic reductions in production yields and/or severe increases in cost to compensate losses in productivity due to lower soil fertility. Soil salinity is a serious problem worldwide causing potential loss of fertility, as plants facing salt stress suffer alterations that adversely affect its growth (Parida and Das, 2005).  Although a possible strategy of coping with salinity may be the use of crops that are able to survive under the installed saline conditions, this would be very limiting and the growth of particular crops with high economic valorisation in such soils would be disabled. Therefore, amelioration of the growth of plants with high yield, biomass and economical value such as maize (Zea mays L.) should be explored. Therefore, this work aimed evaluating the effectiveness of combinations of microorganisms for the recovery of maize productivity in saline soils.  Material and Methods In this study a strategy was set that we relied on the culture in greenhouse conditions of a high value food and energetic crop (maize) inoculated with soil plant growth promoting microbiota –an arbuscular mychorrizal fungi (Rhizophagus irregularis), and a rizospheric (Pseudomonas reactans) and an endophitic (Pantoea alli) plant growth promoting bacteria (PGPB), exposed to soil swith different salinity levels (0, 2.5 and 5 mg NaCl kg-1). A randomized design of 5 treatments for each tested concentration was conducted as follows: 0) non-inoculated control soil with maize ; B) soil with maize  inoculated with P. reactans;  F) soil with maize inoculated with R. irregularis; E) soil with maize inoculated with P. alli; and MIX) soil with maize inoculated with R. irregularis, P. reactans and P.alli.  Roots and shoots of maize plants were harvested 60 days after seeding, washed with deionized water, followed by HCl 0.1 M and again with deionized water. Samples were placed in an oven at 70 ºC for 48 h to determine their dry weights. As the work also aimed at relating the effects of bioinoculation with alterations in plant response to salt stress tissue, root and shoot’s samples were then grinded and sieved to <1 mm and digested in a PerkinElmer Microwave 3000 (Waltham, USA) following the 3052 USEPA method. Sodium content was determined using Inducted Couple Plasma by Optic Emission Spectrometry (ICP-OES) of the digests (Wallinga et al., 1989).       Results and Discussion It was possible to conclude that increases in salt concentration decreased plant biomass production (Table 1). However, all microbial treatments induced increases in maize shoots and roots biomass, with the mixed inocula (MIX) including all tested microbiota generally outperforming the other treatments.   Table 1: Effects of microbial inoculation and salt concentration on maize biomass (g) (n=4). SHOOT sample biomass (g)     sample biomass (g)     sample biomass (g)    0C  2,06 ± 0,02 c   2.5C  1,55 ± 0,16 c   5C  0,92 ± 0,05 c 0B  2,68 ± 0,28 b 2.5B  1,74 ± 0,09 b 5B  1,39 ± 0,12 b 0F  2,40 ± 0,36 b 2.5F  2,41 ± 0,06 a 5F  1,50 ± 0,08 b 0E  2,65 ± 0,23 b 2.5E  1,90 ± 0,08 b 5E  1,40 ± 0,15 b 0MIX  3,00 ± 0,11 a   2.5MIX  2,32 ± 0,08 a   5MIX  1,86 ± 0,13 a F=11,158 (sig=0)   F=69,501 (sig=0)   F=45,943 (sig=0) ROOT sample  biomass (g)     sample biomass (g)     sample biomass (g)    0C  0,75 ± 0,09 d   2.5C  0,44 ± 0,11 d   5C  0,37 ± 0,02 e 0B  1,14 ± 0,09 b 2.5B  0,54 ± 0,08 c 5B  0,46 ± 0,01 c 0F  1,27 ± 0,14 a 2.5F  0,75 ± 0,08 b 5F  0,57 ± 0,02 b 0E  0,90 ± 0,09 c 2.5E  0,42 ± 0,03 d 5E  0,40 ± 0,01 d 0MIX  1,08 ± 0,08 b   2.5MIX  0,99 ± 0,02 a   5MIX  0,61 ± 0,04 a F=20,891(sig=0);          F=54,606(sig=0)         F=120,565(sig=0)      Concerning sodium uptake by maize, as expected it increased with increasing soil concentrations, being the accumulations in roots and shoots generally of the similar order. Generally microbial inoculation avoided Na uptake in either maize roots or shoots, and again the treatment with the mixture of all tested organisms (MIX) showed significantly (P<0.05) best performance, although in some cases treatment with Rhizophagus irregularis (F) showed similar effect.  Table 2: Effects of microbial inoculation and salt concentration in sodium uptake (g/kg plant fry weight) by maize (n=4). SHOOT sample Na (g/kg)   sample Na (g/kg)   sample Na (g/kg)  0C  0,018 ± 0,004 ab   2.5C  7,4 ± 0,2 a   5C  13,2 ± 1,1 a 0B  0,021 ± 0,001 a 2.5B  7,2 ± 1,2 a 5B  11,1 ± 0,8 b 0F  0,007 ± 0,005 c 2.5F  4,6 ± 0,3 b 5F  4,7 ± 0,4 d 0E  0,015 ± 0,001 b 2.5E  7,2 ± 0,1 a 5E  9,2 ± 0,7 c 0MIX  0,009 ± 0,002 c   2.5MIX  5,2 ± 0,8 b   5MIX  3,9 ± 0,2 d F=13,395 (sig=0)   F=11,873 (sig=0)   F=92,763 (sig=0) ROOT sample Na (g/kg)     sample Na (g/kg)     sample Na (g/kg)    0C  1,17 ± 0,14 a   2.5C  7,6 ± 0,9 a   5C  11,5 ± 1,9 a 0B  1,06 ± 0,1 ab 2.5B  7,3 ± 0,7 a 5B  10 ± 0,9 ab 0F  0,93 ± 0,04 bc 2.5F  5,8 ± 0,8 b 5F  10,1 ± 1,3 ab 0E  1,06 ± 0,11 ab 2.5E  5,5 ± 0,5 b 5E  9,06 ± 0,7 bc 0MIX  0,76 ± 0,08 c   2.5MIX  5,5 ± 0,3 b   5MIX  7,4 ± 0,6 c F=7,785(sig=0,001)         F=6,703 (sig=0,003)     F=4,975 (sig=0,009)     This study strongly supports that adequate inoculation is determinant for the recovery of saline soils, and that a combination of soil microbiota including rhizospheric, endophytic bacteria and mychorrizal fungi can allow even a glycophyte as maize to proliferate in such land, rendering it prone to economic valorisation. The adequate combination of AMF, PGPR and host plants, such as energy maize, is determinant for the result of their interaction under stress and consequently for their potential use in management of saline soils.  References Parida AK, Das AB 2005. Salt tolerance and salinity effects on plants: a review. Ecotoxicology and Environmental Safety 60: 324-349.  Wallinga I, Vark W, Houba VJG, Lee JJ 1989. Plant Analysis Procedures. Department of Soil Science and Plant Nutrition, Wageningen: Wageningen Agricultural University, Syllabus.  This work was supported by FCT through  PEst-OE/EQB/LA0016/2011 and EXPL/AGR-PRO/0521/2013. H. Moreira, S. Pereira and A.Marques wish to acknowledge FCT and FSE (III Quadro Comunitário de apoio) for the research grants Ref. SFRH/BD/64584/2009, SFRH/BPD/65134/2009 and EXPL/AGR-PRO/0521/2013, respectively    

Effects of the inoculation with soil microbiota onmaize grown in saline soils

https://repositorio.ucp.pt/bitstream/10400.14/18082/1/EFFECTS%20OF%20THE%20INOCULATION%20WITH%20SOIL.pdf

Effects of the inoculation with soil microbiota onmaize grown in saline soils

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Repositório Institucional da Universidade Católica Portuguesa