Plant growth-promoting bacteria and desert re-vegetation

Plant growth-promoting bacteria
and desert re-vegetation
Yoav Bashan, Esther Puente, Gabor Bethlenfalvay,
Ching Y. Li, Macario Bacilio, Angel E. Carrillo,
Manuel Moreno, Patricia Vazquez, Gina Holguin,
and Luz E. de-Bashan
Environmental Microbiology,
Center for Biological Research of the Northwest,
La Paz, Baja California Sur, Mexico, and
USDA Forest Service, Pacific Northwest Research Station,
Corvallis, Oregon
Palm Springs, March 3 - 7, 2003

THE GOAL
EXTENDING THE POTENTIAL
BENEFITS OF PLANT GROWTH -
PROMOTING BACTERIA (PGPB)
(Such as AZOSPIRILLUM AND OTHER BENEFICIAL
MICROBES)
FROM IMPROVING AGRICULTURAL
PLANT YIELDS
TO ENVIRONMENTAL SOLUTIONS.

DESERT REFORESTATION AIDED
BY PLANT GROWTH-
PROMOTING MICROORGANISMS
THE GOAL : PREVENTING SOIL EROSION
AND REDUCING DUST POLLUTION
BENEFICIAL MICROBES : PGPBs AND
MYCORRHIZAL FUNGI MAY AID IN
REVEGETATION OF THE DESERT

A SCENARIO FOR AN
ECOLOGICAL DISASTER IN
THE DESERT –
A TRUE STORY FROM
NORTHWESTERN MEXICO

U N U DISTURBED DESERT OF THE
FLATLANDS OF BAJA CALIFORNIA
DIRT ROAD
COMPLETE
COVER
OF SOIL BY LOW,
DENSE
VEGETATION

CLEAR-CUTTING OF GIANT CARDON CACTI TO MAKE
1 m
ROOM FOR AGRICULTURE IN BAJA CALIFORNIA
Bashan et al. 2000.
Natural Areas J.

THREE YEARS AFTER CLEAR-CUTTING OF CARDON
ABANDONED RANCH

LONG-TERM DESERTIFICATION
(ABOUT 20 YEARS AFTER CLEAR-CUTTING)
UNDISTURBED AREA
MOON-LIKE LANDSCAPE

TYPICAL SOIL EROSION ON MODERATE SLOPES
AFTER OVER-GRAZING

DUST DEVILS FORMED ON ABANDONED
LANDS DURING A DRY SUMMER

CITY OF LA PAZ. EARLY SUNDAY MORNING.
NO DUST!

UNPAVED STREET. COMMON IN
RURAL NORTHWESTERN MEXICO
LA PAZ HAS OVER 200 km OF UNPAVED STREETS

DUST CLOUD ABOVE THE CITY OF LA PAZ
ON A TYPICAL MORNING
BAY OF LA PAZ
(CITY ON FAR SHORE)

C H R O NIC RES PIR A T O R Y ILLNESSES IN
BAJA CALIFORNIA SUR, MEXICO
YEAR POPULATION AFFECTED (%)
1992 32
1995 31
1997 33
MOST SUFFERERS ARE CHILDREN (source: Ministry of Health)

Our proposal for an environmental solution
Re-vegetate abandoned agricultural land
with cacti and desert trees and control
urban dust-creating areas.
For rural areas, many cacti are
excellent top-soil stabilizers

The advantages of
arborescent cacti for
re-vegetation…..
• NUMEROUS!!!
• So, if they are such “dream
plants,” why haven’t they been
used?

THE MAIN PROBLEMS OF USING CACTI ARE …
• ALL ARE VERY SLOW
GROWERS,
•MANY HAVE POOR ABILITY,
AS SEEDLINGS, TO BECOME
ESTABLISHED
THIS YOUNG CARDON IS
O VE R 100 YEARS OLD … ..

Proposed solution
Major issues in desert reforestation
How to establish a desert plant population
How to increase survival of plants after transferring
them to the site
How to enhance their growth relative to the
natural growth of vegetation

Possible microbial solutions?
Artificial inoculation of desert plants with
beneficial microorganism (bacteria and
mycorrhizae fungi, alone and mixed)
Mimic typical vegetation reproduction patterns in
the desert (nurse-tree-microbial micro-ecosystem)

1 cm
INO C U LATION OF CA R D O N
CACTUS WITH Azospirillum
UNINOCULATED
Puente and Bashan, 1993. Symbiosis
INOCULATED

EFFECT OF INOCULATION WITH AZOSPIRILLUM ON
CARDON CACTUS GROWING IN SOILS OBTAINED
FROM NATURAL, VEGETATED SITES
% of control
(growth
medium)
250
200
150
100
50
0
Poor soil
Rich soil
Dry weight Root
Length
Carrillo-Garcia et al. 2000. Restoration Ecology

Increase in the volume of cardon cactus,
grown in an eroded area, and inoculated
with Azospirillum brasilense
Increase in volume (%)
35
30
25
20
15
10
5
0
1
3
5
Inoculated
Naturally grown
Bashan et. al. 1999. Can. J. Microbiol.
7
Noninoculated
9 13 17 21 25 29 33 37 41
11 15 19 23 27 31 35 39
Months

Increase in proton extrusion from roots and
acidification of the rhizosphere of inoculated cacti
• Cacti inoculated with
Azospirillum extrude
more protons
• The pH of the
rhizosphere is lower
• Adsorption of
minerals increased
{
Rhizosphere pH
7.4
7.3
7.2
7.1
7
6.9
6.8
Carrillo et al. Naturwissenshften, 2002
Bulk soil
Soil +
ammonium
Soil +
Ammonium +
Azospirillum

MG/KG SOIL
1,400
1,200
1,000
800
600
400
200
THE LEVELS OF N AND P
IN THE REVEGETATION AREA
0
NITROGEN PHOSPHORUS
UNDISTURBED
BEFORE
100
After After
MG/KG SOIL
Bashan et al. Can. J. Microbiol. 1999
80
60
40
20
0
UNDISTURBED
BEFORE

Log cfu/g (roots or soil)
7
6
5
4
3
2
1
SURVIVAL OF Azospirillum IN THE
RHIZOSPHERE AND BULK SOIL OF
REVEGETATED AREA OF CARDON CACTUS
BULK
SOIL
RHIZOSPHERE
SOIL
0
inoculation 1 month 6 months 12 months 24 months
BASHAN ET AL. 1999. CAN J. MICROBIOL

SOIL EROSION (m3/ha)
Soil erosion and soil reclamation
with and without cactus cultivation
Non-cactus cultivating area
0
-100
-200
-300
-400
-500
-600
0 1 1.5 2 3.5
YEARS
Bashan et. al. 1999
SOIL ACCUMULATION (M3/HA)
50
40
30
20
10
CACTUS CULTIVATION
0
0 1 1.5 2 3.5
YEARS

Distribution of small roots in the uppermost
5 cm topsoil in rainy and dry seasons 2.5
years after transplanting
Soil surface
Depth (cm)
Pachycereus
pringlei
Stenocereus
thurberi
Lophocereus
schottii
Rainy Dry Rainy Dry Rainy Dry Rainy
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Bashan et al. Can. J. Microbiol. 1999
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Distribution of small roots in the uppermost
5 cm topsoil in rainy and dry seasons 2.5
years after transplanting
Soil surface
Depth (cm)
Pachycereus
pringlei
Stenocereus
thurberi
Lophocereus
schottii
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Bashan et al. Can. J. Microbiol. 1999
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Distribution of small roots in the uppermost
5 cm topsoil in rainy and dry seasons 2.5
years after transplanting
Soil surface
Depth (cm)
Pachycereus
pringlei
Stenocereus
thurberi
Lophocereus
schottii
Rainy Dry Rainy Dry Rainy Dry Rainy
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Bashan et al. Can. J. Microbiol. 1999
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DUST LAYER
MECHANISM OF SOIL ACCUMULATION
ASSOCIATED WITH CACTI
AND THE CYCLE GOES ON……..
Bashan et al., Can. J. Microbiol. 1999

CONCLUSIONS OF THIS STUDY
Natural
VS.
Inoculated

What had happened to the
What happened to the inoculated cacti?
inculated cacti?
Had a high survival rate
Developed more rapidly
Compared to: uninoculated control cacti and
natural vegetation during 3.5-years

What had happened to the
What happened to the eroded urban soil?
eroded urban soil?
Soil erosion in the experimental
area ceased.
Small, but significant soil
accumulation occurred.

THE USE OF ENDOPHYTES FROM WILD
PLANTS AS PLANT GROWTH
PROMOTERS
Accelerating creation of desert soil by
microbes associated with plants?

CARDON CACTI GROWING IN ROCKS IN THE ABSENCE OF SOIL:
AN EXAMPLE OF ROCK-WEATHERING PLANTS
Bashan et al. Plant Biology. 2002
0.5 M

MAMILARIA CACTI GROWING IN ROCKS IN THE ABSENCE OF SOIL:
ANOTHER EXAMPLE OF ROCK-WEATHERING PLANTS
SMALL MAMILARIA CACTI
AT DENSITIES OF UP TO
100 / SQUARE METER
5 cm
Bashan et al. Plant Biology. 2002

1 M
WILD FIG TREES GROWING IN CLIFF: ANOTHER ROCK-WEATHERING PLANT
Bashan et al. Plant Biology. 2002
Roots
Rocks
1 M

YOUNG CARDON CACTUS
GROWING IN A ROCK
WITHOUT SOIL
BROKEN ROCK
ROOTS
Bashan et al. Plant Biology. 2002

COLONIZATION OF ROOT SURFACE OF CARDON
CACTUS GROWING IN ROCKS IN THE ABSENCE OF SOIL
BACTERIA
ROOT SURFACE
PUENTE ET AL. 2003. Plant Biology (under consideration)

INTRACELLULAR COLONIZATION OF
CARDON CACTUS ROOTS GROWING IN
ROCKS WITHOUT SOIL
CELL INTERIOR
PUENTE ET AL. 2003. NATURE (UNDER CONSIDERATION)
FLUORECESNCE
ROOT

What kinds of microbial communities are residing
on the roots of cacti growing in rocks?
Nitrogen fixers
Phosphate solubilizers
Plant hormones producers?
Rock and mineral dissolving bacteria
Mycorrhizae fungi?
Fungi
Actinomycetes
Fluorescent pseudomonades
PUENTE ET AL. 2003. PLANT BIOLOGY

Inoculation of alder seedlings growing in
(Li, unpublished)
crushed basalt with Frankia
(a nitrogen-fixing bacteria)
Inoculated
Uninoculated
Inoculated
Uninoculated

USING PGPBs FOR DESERT
REFORESTATION –
GENERAL CONCLUSIONS
8 INOCULATION OF CACTI WITH BACTERIA
CAN ENHANCE THEIR ESTABLISHMENT
AND GROWTH IN DISTURBED AREAS
AND CAN STABILIZE SOIL
8 ENDOPHYTIC MICROBES SHOULD BE
INCORPORATED INTO TESTS FOR
PROMOTION OF GROWTH OF DESERT
PLANTS

MESSAGE TO TAKE HOME
THE USE OF PLANT GROWTH -
PROMOTING MICROORGANISMS
SHOULD BE EXTENDED
FROM AGRICULTURAL TO
ENVIRONMENTAL PROBLEMS
All published papers are available as PDF files at:
http://www.cibnor.org/grupo/gma/ipublica.php