Transcript No Slide Title

Biomass Production, Nutrient Accumulation, and Tolerance to Heavy Metal
of Selected Winter Canola Cultivars
ABSTRACT
Species of the Brassicaceae family may be excellent for uptake of heavy
metals and nutrients. In this study, we evaluated the efficiency of
eleven promising winter canola (Brassica napus) cultivars for their
nutrient (Al, Ca, K, Mg, Mn, N, Na, S and P) uptake in the field and
uptake of heavy metals (Se, Cd, Cu, Fe, Zn, and Cr) in the greenhouse.
In the field study, three plants cultivar-1 replication-1 were randomly
sampled at three different growth stages (rosette, anthesis and
senescence) and partitioned into different parts, e.g., leaves, roots,
stems, flowers, pods and seeds, to determine above-and below-ground
biomass, and accumulation of nutrients. In the greenhouse study of
heavy metals uptake, seedlings of all test cultivars were evaluated with
four different heavy metals concentrations in the range found in
Alabama soils and compared to an untreated control. Preliminary data
indicate significant variations among the cultivars in roots (P< 0.0001)
and stem (P = 0.0335) biomass production. The cultivar Titan
produced significantly higher per plant biomass (11.3g of dry matter
plant-1), while cultivar Kronos produced the least (5.5g of dry matter
plant-1). Cultivars and harvest stages showed significant differences in
nutrient uptake. The cultivar Kronos, which produced the least
biomass, showed the highest accumulation of Al, Zn, Fe and Mn in its
tissues. The differences between biomass production and nutrient
uptake among the canola cultivars may identify their genetic potential
for phytoremediation.
INTRODUCTION
Canola (Brassica napus)
A cash crop that is known for its desirable oil quality and as feedstock for
bio-diesel.
Canola is the second largest oil producing crop in the world providing up
to 13% of the world’s oil supply (Raymer, 2002).
In North America, canola is grown throughout the Pacific Northwest,
Upper-Midwest and Canada.
Scientists have identified canola as a possible candidate for
phytoremediation to remediate soils contaminated with heavy metals.
Canola has a tap root system and profuse root hairs that allows the plant
to be well-equipped for hyperaccumulation.
Pollution of soils by heavy metals is a problem that exists from activities
involving the agricultural industries, mining industries, and chemical
industries (Nascimento et al. 2005).
Since the early 1900s, heavy metal contamination of the biosphere has
been increasing at a rapid rate causing major health problems to humans
worldwide (Prasad et al., 2003).
Celeste P. Bell*, Ernst Cebert, Rufina Ward and Zachary Senwo
Department of Plant and Soil Science, Alabama A&M University
Normal, AL 35762
Canola during vegetative growth
Dried weight was recorded for the whole plant and each
component.
The plant parts were grounded then digested with a
Microwave Digester, using 10 ml of 70% Nitric Acid and
analyzed.
Inductively Coupled Plasma (ICP) was used to
determine the content of heavy metals and minerals
nutrients.
SAS (Statistical Analysis System, ver 9.1, PROC GLM
and Tukey’’s mean separation analysis) was used to
determine differences among:
 Cultivars
 Harvest
 Source
SAS Graph-N-Go and ODS Graphics were used for
graphical output.
Experiment II (Greenhouse)
In this study three canola cultivars: Abilene, Jetton and
Titan were grown in the greenhouse to observed and
evaluated the impact of heavy metals of seedling growth.
►Five heavy metals were
used: Cd, Cr, Cu, Mn
and Zn plus a control
Canola plots at senescence
Results for canola cultivars’ biomass production (grams/plant), uptake of selected
nutrients (mg/kg dry weight), and the impact of heavy metals on seedlings: root biomass,
leaf damage and leaf area development are shown on figures 1a – 3c.
Distribution chart showing total biomass produced by each
cultivar and its source. Statistical differences were:
Cultivars**
P < 0.0001
Harvest**
P < 0.0001
Source**
P < 0.0001
Statistical differences for distribution of manganese (Mn) by
cultivars, harvest and source:
Cultivars
NS
Harvest*
P < 0.0001
Source*
NS
1a
Statistical differences for distribution of iron (Fe) by cultivars,
harvest and source:
Cultivars
NS
Harvest**
P < 0.0001
Source**
P < 0.0001
►Samples were collected
after 4 weeks of growth.
Statistical differences for distribution of copper (Cu) by
cultivars, harvest and source:
Cultivars
NS
Harvest**
P < 0.0001
Source**
P < 0.0001
1b
1c
Statistical differences for distribution of magnesium (Mg) by
cultivars, harvest and source:
Cultivars*
P = 0.0001
Harvest**
P < 0.0001
Source**
P < 0.0001
Statistical differences for distribution of zinc (Zn) by cultivars,
harvest and source:
Cultivars*
P = 0.0295
Harvest**
P < 0.0001
Source**
P < 0.0001
2b
2a
2c
Table 1. Range of heavy metals (in ppm, Alabama soils)
used in this study to evaluate the impact on seedling
growth of three canola cultivars.
Heavy
metals
Cd
Level
1
0.20
Level
2
1.0
Level
3
2.0
Level
4
3.0
SOILS OF NORTH ALABAMA
Cr
13.4
50.0
75.0
150
The Ultisols soils of North Alabama contain excessive level of Fe, Mn,
Zn, Cr, Ni, Cu, Pb and Cd. Fe and Mn are the top pollutants accumulating
with clay in the Bt horizons (Senwo and Tazisong, 2004).
Cu
3.2
27.0
54.0
82.0
This project investigated the variations among winter canola cultivars for
production of biomass and response of seedlings to selected heavy metals
in the range found in Alabama soils.
Canola field at flowering
Mn
30.3
1,550
3,100
4,645
Zn
22.6
113.0
227.0
340.0
Figures 1a, - 2c show the biomass and nutrient accumulation for canola cultivars selected for their superior performance in northern Alabama .
Statistical differences for distribution of root biomass by
cultivars, metals and levels:
Cultivars**
P < 0.0001
Metals*
P = 0.0386
Levels
NS
Statistical differences for distribution of leaf damage by
cultivars, metals and levels:
Cultivars
NS
Metals**
P < 0.0001
Levels**
P < 0.0001
3a
Statistical differences for distribution of leaf area by
cultivars, metals and levels:
Cultivars
NS
Metals**
P < 0.0001
Levels
NS
3b
3c
MATERIALS AND METHODS
Eleven genetically diverse canola cultivars were selected from the
National Winter Canola Variety Trials grown at the Winfred-Thomas
Agricultural Research Station, Alabama A&M University, in
Meridianville, Alabama, and evaluated for biomass production and
accumulation of nutrients.
Plot size consists of six rows with 18-cm row spacing, 1.3-meter wide
and 6-meter long.
Figures 3a, b and c show the response of seedlings from three winter canola cultivars treated with selected heavy metals at four different levels of concentration.
CONCLUSION
Significant statistical differences among cultivars for biomass production and among nutrients tested,
indicate that such genetic differences will allow the selection of canola cultivars for their higher capacity to
accumulate such elements as: Zn and Fe. However, highly significant difference exists for time of harvest
and plant source (roots, leaves, stems, flowers, pods and seeds) where nutrients accumulate.
Samples (3 plants/cultivars/rep/harvest) were collected at three
different growth stages:
 Rosette
 Flowering
 Senescence
(120 days after planting, DAP)
(150 DAP)
(250 DAP)
The impact of heavy metals on canola seedling development was adversely affected by manganese; leaf
damage to all cultivars gradually increased from no damage at level 1 to severe (leaf death) at level 4 (Figure
3b). Among the three cultivars evaluated in the heavy metal study, seedlings of Titan was least affected by
increasing levels of heavy metals, except for root biomass where cultivar Jetton was significantly better.
Each sample was partitioned into different components:
Leaves and roots
(Rosette –
1st harvest)
Leaves, roots, stems and flowers (Spring –
2nd harvest)
Roots, stems, pods and seeds
(Senescence – 3rd harvest)
ACKNOWLEDGMENT
The Kansas State University National Winter Canola Variety Trial
(NWCVT). Anson Joseph and Geoffrey Reid for their help in field
and laboratory work.
These results represent preliminary analysis of field and greenhouse studies. The data show that winter
canola cultivars can be selected for conditions in the southern region of the United States and as a candidate
for phytoremediation.
REFERENCES
Nascimento, Clistenes, D. Amarasiriwardena, B. Xing. 2005. Comparison of
natural organic acids and synthetic chelates at enhancing phytoextraction of
metals from a multi-metal contaminated soil. Environmental Pollution. 1-10.
Prasad, Vara Narasimha Majeti, H. Freitas. 2003. Metal hyperaccumulation in plants
– Biodiversity prospecting for phytoremediation technology. J.
Biotechnology.
6:285-321.
Raymer, P.L. 2002. Canola: An emerging oilseed crop. p. 122–126. In: J. Janick and
A. Whipkey (eds.), Trends in new crops and new uses. ASHS Press,
Alexandria, VA.
Senwo, Z. N., I. A. Tazisong. 2004. Metal content in soils of Alabama. Comm. Soil
Sci. and Plant Analysis. 35: 2837-2848.